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Corresponding author: Mike Duran ( pmlodingi@yahoo.com ) Academic editor: Anthony Herrel
© 2021 Mike Duran.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Duran M (2021) An annotated checklist of the amphibians and reptiles of North Padre Island, Texas, USA, with comparisons to adjacent barrier island and mainland herpetofauna. ZooKeys 1073: 119-175. https://doi.org/10.3897/zookeys.1073.57241
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Padre Island is the world’s longest barrier island and includes the longest stretch of undeveloped barrier island in the world. Largely due to harsh environmental conditions and difficult access, only cursory and incomplete checklists and subjective estimates of abundance have been produced. The results of an inventory of amphibians and reptiles of North Padre Island conducted 2002–2020, including the results of extensive field surveys conducted 2002–2003, are reported herein. Natural history museum and iNaturalist records are summarized and compared among North and South Padre and Mustang islands and the mainland portion of the seven counties in which the islands occur. The conservation status of rare species and extirpation of others is noted. The morphology and taxonomic status of some unique occurrences are discussed. Eleven species of amphibians and 39 species of reptiles presently occur or have occurred naturally or as introduced or accidental species on North Padre Island. Twelve species of amphibians and 50 species of reptiles occur or have occurred on North Padre, South Padre, and Mustang islands. Thirty-one species of amphibians and 93 species of reptiles have been reported from the seven counties in which the islands occur.
Reptiles, amphibians, checklist, inventory, Padre Island, Texas, Mustang Island, North Padre Island, conservation, historical record, museum, iNaturalist
Extending for 178 km along the southern Texas coast, from Packery Channel in Corpus Christi to the Rio Grande River delta at the southern tip of the state, Padre Island is the world’s longest barrier island (Fig.
Several models have been proposed to explain the formation of Padre and other barrier islands. The consensus among coastal geologists today, while recognizing that no one model exclusively explains barrier island formation, postulates that at the end of the Holocene, ~ 5,000–4,500 years ago, rising sea levels reached ~ 4.6 m above where they are today, and sandbars and shoals parallel to the shoreline began to form. When the sea reached its current level, ~ 2,800–2,500 years ago, those sandbars and shoals coalesced to form Padre Island and created bays and lagoons between the island and the mainland (
Padre and other barrier islands are ever-changing as winds and currents regularly alter beaches, dunes, and tidal inlets. During extreme tidal events, freshwater wetlands and grasslands may be flooded with saline water from the Gulf of Mexico and hypersaline water from the inland lagoon. Dunes erode to depressions and flats. Storm surges sometimes alter the island suddenly, creating wash-over channels, closing or opening of passes, and flooding inland lagoons with sea water.
The lagoon formed inland of Padre Island, the Laguna Madre, was mostly isolated from the Gulf of Mexico prior to the dredging of Mansfield Channel in 1957 and received little freshwater inflow; together with the Laguna Madre de Tamaulipas, it became the largest of only six hypersaline bays and lagoons in the world (
While plant communities on North Padre Island are generally interdigitating and unevenly distributed, an idealized spatial vegetation profile is helpful to visualize the distribution of ecological zones from the Gulf of Mexico, proceeding westward to the Laguna Madre (adapted from
According to NOAA (2021), Padre Island becomes considerably drier from the northern end at Corpus Christi, which receives 80.5 cm of rainfall per year, to the mid-point at Port Mansfield which receives 65.8 cm per year. Port Isabel, at the southern end of Padre Island, receives ~ 73.4 cm per year. The vegetation of North Padre Island gradually becomes less dense, north to south, i.e., the northern end vegetation is relatively lush and dense, while much of the landscape near either side of the Mansfield Channel is sparsely vegetated with extensive areas of bare sand.
Average annual temperatures become slightly warmer, north to south, with Corpus Christi at 22.3 °C, Port Mansfield 22.8 °C, and Port Isabel 23.1 °C. In some years, temperatures never drop below freezing. Most of the rainfall occurs in late summer and early fall, particularly at the southern end, where Port Isabel receives ~ 35% of its annual rainfall in September and October (NOAA 2021; https://www.ncdc.noaa.gov/cdo-web).
A review of the relevant literature and museum specimens was conducted, through 08 October 2020, for the five counties in which the islands occur (Cameron, Kenedy, Kleberg, Nueces, Willacy) and for the two counties adjacent to Corpus Christi Bay (Aransas and San Patricio; hereafter “the seven counties”). Museum records were reviewed in September 2021, and new species added after 08 October 2020 are included. Research grade iNaturalist records for the South Texas barrier islands were compiled through 08 October 2020. Research grade iNaturalist observations of new species added between 08 October 2020 and 12 September 2021 are also included. For the most recent review of the museum database, I obtained most of the records through Vertnet.org (2021). The museum and iNaturalist searches of the seven counties captured a few records from San José Island, Harbor Island, South Bird Island, and other islands in the Laguna Madre and Corpus Christi Bay. Those records are labelled “other islands” (OI).
For the 2002–2003 surveys, I used ArcView 3.3 with the Hawth Tools extension, Random, to randomly select fifteen study sites on North Padre Island within six ecological zones (see previous section for discussion of ecological zones) within three geographical zones. Herpetofauna were sampled in six ecological zones: 1) back-beach and foredunes, 2) dune/swale complex 3) grasslands, 4) wetlands, 5) grassland/wetland complex, and 6) sand dunes. Herpetofauna were not sampled on the forebeach, saline flats, or wind tidal flats. The northernmost study site, just inside the PINS boundary, 13.8 km south of Packery Channel, was 102 km north of the southernmost study site, 250 m north of the Mansfield Channel. Two sites were selected non-randomly so that wetlands would be adequately sampled. The original design was based on ecological zones delineated by
Aquatic surveys were conducted opportunistically at all permanent ponds and most ephemeral pools from ~ 18 km south of Packery Channel to ~ 27 km south of Packery Channel and at ephemeral pools that occurred within or near the randomly selected study sites. During 2002 and 2003, road-searching and calling frog surveys were conducted from the southern end of Park Road 22, north to the intersection of Park Road 22 with State Highway 360. Calling-frog surveys were conducted and audio-recorded opportunistically (during and after heavy rainfall), and at predetermined points for 10 minutes (after the methodology of
Field work and trap installation and removal was performed by a team that consisted of The Nature Conservancy and National Park Service (NPS) personnel and volunteers. For terrestrial and semi-aquatic species, our team installed two variations of drift-fence/pitfall arrays. The first consisted of three equally spaced drift-fence arms, which originated at a center 19-liter pitfall buried to the rim and extended 7 m to 19-liter pitfalls at the ends and at midpoints, so that each array included seven pitfalls. The second type of array consisted of a 1.2 m × 1.2 m × 45.7 cm box, constructed after the design of
Scientific and common names follow
This work was performed under the authority of Texas Parks and Wildlife Department scientific research permit SPR-0302-204, US National Park Service scientific research and collecting permits PAIS-2003-SCI-0008, PAIS-2009-SCI-0012, and PAIS-2014-SCI-0006, and US Fish and Wildlife Service permit TE820085-0.
Abbreviations used in this paper are as follows:
BPP Bayesian Phylogenetics and Phylogeography
GIS Geographic information system
NPI North Padre Island
NPS US National Park Service
OI other islands
PINS Padre Island National Seashore
SPI South Padre Island
TAMUK Texas A&M University at Kingsville
TCWC Biodiversity Research and Teaching Collections at Texas A&M University
URL Uniform Resource Locator (link)
VSR Ventral scale rows
Forty-four institutions held 14,830 specimens from the seven counties including 1751 specimens from the South Texas barrier islands held by 26 institutions and 47 specimens held by six institutions from San José Island, Harbor Island, South Bird Island, and other small man-made and natural islands in the Laguna Madre and Corpus Christi Bay (Table
Museums which contain amphibian and reptile specimens from the mainland portion of the seven adjacent counties (ML), Mustang Island (MI), North and South Padre (NPI and SPI), other small islands in the Laguna Madre and Corpus Christi Bay adjacent to Mustang Island (OI).
Inst code | Institution name | ML | MI | NPI | OI | SPI | Total |
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American Museum of Natural History | 4 900 | 32 | 338 | 28 | 51 | 5 349 |
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U. of Texas at Austin - Texas Natural History Collections | 1 882 | 232 | 55 | 13 | 13 | 2 195 |
TCWC | Texas A&M U. Biodiversity Research and Teaching Collections | 1 306 | 76 | 151 | 3 | 18 | 1 554 |
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National Museum of Natural History, Smithsonian Institution | 616 | 8 | 46 | 1 | 6 | 677 |
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Baylor University, Mayborn Museum Complex | 472 | 7 | 17 | 50 | 546 | |
UTA | U. of Texas at Austin - Texas Natural History Collections | 371 | 18 | 12 | 63 | 464 | |
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Angelo State Natural History Collection | 108 | 19 | 315 | 442 | ||
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University of Kansas Biodiversity Institute | 389 | 22 | 1 | 1 | 8 | 421 |
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Louisiana State University Museum of Natural Science | 396 | 4 | 5 | 1 | 406 | |
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University of Michigan Museum of Zoology | 404 | 1 | 1 | 406 | ||
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Florida Museum of Natural History | 311 | 6 | 1 | 1 | 319 | |
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Museum of Vertebrate Zoology, UC Berkeley | 113 | 169 | 3 | 285 | ||
FMNH | Field Museum of Natural History | 277 | 277 | ||||
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Museum of Comparative Zoology, Harvard University | 204 | 7 | 211 | |||
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Carnegie Museum of Natural History | 156 | 5 | 11 | 172 | ||
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San Diego Natural History Museum | 162 | 2 | 1 | 165 | ||
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Natural History Museum of Los Angeles County | 100 | 16 | 1 | 117 | ||
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University of Colorado Museum of Natural History | 83 | 12 | 2 | 97 | ||
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Natural History Museum of Utah | 72 | 1 | 73 | |||
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Academy of Natural Science Philidelphia | 65 | 65 | ||||
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Chicago Academy of Sciences | 65 | 65 | ||||
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University of British Columbia Beaty Biodiversity Museum | 59 | 59 | ||||
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North Carolina Museum of Natural Sciences | 57 | 57 | ||||
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California Academy of Sciences | 54 | 1 | 55 | |||
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Cornell University Museum of Vertebrates | 49 | 1 | 50 | |||
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Michigan State University Museum | 45 | 45 | ||||
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University of Arizona Museum of Natural History | 44 | 44 | ||||
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University of Texas at El Paso Biodiversity Collections | 36 | 1 | 1 | 38 | ||
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Monte L. Bean Museum, Brigham Young University | 29 | 2 | 31 | |||
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Sam Noble Oklahoma Museum of Natural History | 17 | 7 | 24 | |||
CLO | Macaulay Library Audio and Video Collection | 21 | 21 | ||||
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Auburn University Museum of Natural History | 19 | 19 | ||||
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Fort Hays Sternberg Museum of Natural History | 10 | 6 | 1 | 17 | ||
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Southeastern Louisiana University | 8 | 2 | 10 | |||
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Georgia Southern University | 7 | 1 | 8 | |||
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New Brunswick Museum | 8 | 8 | ||||
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Illinois State Museum | 7 | 7 | ||||
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Museum of Southwestern Biology | 7 | 7 | ||||
PMNS | Perot Museum of Nature and Science | 5 | 2 | 7 | |||
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Buffalo Society of Natural Sciences | 5 | 5 | ||||
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Milwaukee Public Museum | 5 | 5 | ||||
YPM | Yale Peabody Museum | 3 | 0 | 3 | |||
PBDB | Paleobiology Database | 2 | 2 | ||||
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Sam Noble Oklahoma Museum of Natural History | 2 | 2 | ||||
Total | 12 951 | 639 | 971 | 47 | 222 | 14 830 |
Museum and iNaturalist records of amphibians and reptiles of the South Texas barrier islands. ML = mainland; MI = Mustang Island; NPI = North Padre Island; SPI = South Padre Island; OI = San José Island (in Aransas Co.) and other natural and manmade islands in the Laguna Madre and Corpus Christi Bay.
Taxon |
iNaturalist Observations | Museum specimen records | All totals | ||||||||
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MI | NPI | SPI | iNatTot | MI | ML | NPI | OI | SPI | MusTot | ||
AMPHIBIA | 144 | 206 | 37 | 387 | 144 | 5 789 | 64 | 3 | 33 | 6 033 | 6 420 |
Anura | 144 | 206 | 37 | 387 | 144 | 4 797 | 64 | 3 | 33 | 5 041 | 5 428 |
Bufonidae | 30 | 18 | 94 | 132 | 1 028 | 9 | 1 169 | 1 263 | |||
Bufo cognatus | 4 | 4 | 4 | ||||||||
Bufo debilis | 38 | 38 | 38 | ||||||||
Bufo horribilis | 2 | 2 | 2 | ||||||||
Bufo nebulifer | 46 | 18 | 18 | 82 | 8 | 447 | 7 | 462 | 544 | ||
Bufo speciosus | 124 | 528 | 652 | 652 | |||||||
Bufo woodhousii | 12 | 12 | 8 | 2 | 10 | 22 | |||||
Rhinella marina | 1 | 1 | 1 | ||||||||
Eleutherodactylidae | 3 | 4 | 7 | 184 | 3 | 187 | 194 | ||||
Eleutherodactylus planirostris | 2 | 2 | 2 | 2 | 4 | ||||||
Eleutherodactylus campi | 3 | 2 | 5 | 184 | 1 | 185 | 190 | ||||
Hylidae | 64 | 95 | 14 | 173 | 3 | 1 052 | 15 | 28 | 1 098 | 1 271 | |
Acris blanchardi | 72 | 72 | 72 | ||||||||
Hyla cinerea | 9 | 21 | 30 | 1 | 486 | 14 | 501 | 531 | |||
Hyla squirella | 55 | 66 | 10 | 131 | 2 | 80 | 28 | 110 | 241 | ||
Hyla versicolor complex | 19 | 19 | 19 | ||||||||
Osteopilus septentrionalis | 1 | 1 | 1 | ||||||||
Pseudacris clarkii | 8 | 8 | 239 | 1 | 240 | 248 | |||||
Pseudacris streckeri | 80 | 80 | 80 | ||||||||
Smilisca baudinii | 3 | 76 | 76 | 79 | |||||||
Microhylidae | 14 | 11 | 25 | 512 | 2 | 2 | 516 | 541 | |||
Gastrophryne carolinensis | 14 | 9 | 23 | 3 | 2 | 5 | 28 | ||||
Gastrophryne olivacea | 2 | 2 | 364 | 364 | 366 | ||||||
Hypopachus variolosus | 145 | 2 | 147 | 147 | |||||||
Ranidae | 16 | 9 | 1 | 26 | 4 | 851 | 8 | 2 | 865 | 891 | |
Rana berlandieri | 14 | 7 | 1 | 22 | 3 | 597 | 7 | 607 | 629 | ||
Rana catesbeianus | 2 | 1 | 3 | 1 | 76 | 77 | 80 | ||||
Rana sphenocephala | 1 | 1 | 178 | 1 | 2 | 179 | 180 | ||||
Scaphiopodidae | 1 | 61 | 62 | 5 | 1 170 | 30 | 1 | 1 206 | 1 268 | ||
Scaphiopus couchii | 794 | 794 | 794 | ||||||||
Scaphiopus hurterii | 1 | 61 | 62 | 5 | 235 | 30 | 1 | 271 | 333 | ||
Spea bombifrons | 90 | 90 | 90 | ||||||||
Spea multiplicata | 51 | 51 | 51 | ||||||||
Caudata | 992 | 992 | 992 | ||||||||
Ambystomatidae | 132 | 132 | 132 | ||||||||
Ambystoma mavortium | 132 | 132 | 132 | ||||||||
Salamandridae | 217 | 217 | 217 | ||||||||
Notophthalmus meridionalis | 216 | 216 | 216 | ||||||||
Notophthalmus viridescens | 1 | 1 | 1 | ||||||||
Sirenidae | 643 | 643 | 643 | ||||||||
Siren intermedia | 643 | 643 | 643 | ||||||||
REPTILIA | 1 317 | 2 637 | 563 | 4 517 | 495 | 7 162 | 907 | 44 | 189 | 8 797 | 13 314 |
Crocodylia | 321 | 1 | 174 | 496 | 5 | 5 | 501 | ||||
Alligatoridae | 321 | 1 | 174 | 496 | 5 | 5 | 501 | ||||
Alligator mississippiensis | 321 | 1 | 174 | 496 | 5 | 5 | 501 | ||||
Squamata | 704 | 2 504 | 227 | 3 435 | 476 | 6 403 | 889 | 41 | 175 | 7 984 | 11 419 |
Sauria | 508 | 1 910 | 216 | 2 634 | 424 | 3 105 | 773 | 21 | 171 | 4 494 | 7 128 |
Anguidae | 9 | 1 107 | 1 | 1 117 | 13 | 101 | 18 | 3 | 1 | 136 | 1 253 |
Ophisaurus attenuatus | 9 | 1 107 | 1 | 1 117 | 13 | 101 | 18 | 3 | 1 | 136 | 1 253 |
Crotaphytidae | 1 | 1 | 1 | ||||||||
Crotaphytus collaris | 1 | 1 | 1 | ||||||||
Dactyloidae | 455 | 139 | 145 | 739 | 3 | 201 | 204 | 943 | |||
Anolis carolinensis | 53 | 30 | 19 | 102 | 3 | 191 | 194 | 296 | |||
Anolis sagrei | 402 | 109 | 126 | 637 | 10 | 10 | 647 | ||||
Eublepharidae | 2 | 2 | 2 | ||||||||
Coleonyx brevis | 2 | 2 | 2 | ||||||||
Gekkonidae | 7 | 38 | 3 | 48 | 2 | 220 | 2 | 224 | 272 | ||
Hemidactylus mabouia | 4 | 4 | 4 | ||||||||
Hemidactylus turcicus | 7 | 38 | 3 | 48 | 2 | 216 | 2 | 220 | 268 | ||
Iguanidae | 5 | 5 | 5 | ||||||||
Ctenosaura acanthura | 1 | 1 | 1 | ||||||||
Ctenosaura pectinata | 3 | 3 | 3 | ||||||||
Ctenosaura similis | 1 | 1 | 1 | ||||||||
Phrynosomatidae | 14 | 509 | 53 | 576 | 385 | 1 816 | 718 | 14 | 155 | 3 088 | 3 664 |
Cophosaurus texanus | 2 | 2 | 2 | ||||||||
Holbrookia propinqua | 13 | 509 | 49 | 571 | 379 | 966 | 717 | 10 | 154 | 2 226 | 2 797 |
Holbrookia subcaudalis | 75 | 75 | 75 | ||||||||
Phrynosoma cornutum | 1 | 1 | 6 | 180 | 1 | 2 | 189 | 190 | |||
Sceloporus consobrinus | 117 | 117 | 117 | ||||||||
Sceloporus cyanogenys | 5 | 5 | 5 | ||||||||
Sceloporus grammicus | 195 | 195 | 195 | ||||||||
Sceloporus olivaceus | 1 | 3 | 4 | 139 | 1 | 1 | 141 | 145 | |||
Sceloporus variabilis | 136 | 1 | 137 | 137 | |||||||
Urosaurus ornatus | 1 | 1 | 1 | ||||||||
Scincidae | 2 | 37 | 2 | 41 | 2 | 268 | 11 | 1 | 282 | 323 | |
Plestiodon obsoletus | 1 | 6 | 7 | 54 | 7 | 61 | 68 | ||||
Plestiodon tetragrammus | 2 | 2 | 132 | 1 | 133 | 135 | |||||
Scincella lateralis | 1 | 31 | 32 | 2 | 82 | 4 | 88 | 120 | |||
Teiidae | 21 | 80 | 12 | 113 | 19 | 491 | 24 | 4 | 14 | 552 | 665 |
Aspidoscelis gularis | 7 | 7 | 1 | 380 | 6 | 387 | 394 | ||||
Aspidoscelis laredoensis | 1 | 1 | 1 | ||||||||
Aspidoscelis sexlineatus | 21 | 80 | 5 | 106 | 18 | 110 | 24 | 4 | 8 | 156 | 262 |
Serpentes | 196 | 594 | 11 | 801 | 52 | 3 298 | 116 | 20 | 4 | 3 490 | 4 291 |
Colubridae | 166 | 584 | 9 | 759 | 45 | 2 594 | 94 | 19 | 4 | 2 756 | 3 515 |
Arizona elegans | 7 | 6 | 1 | 14 | 6 | 41 | 8 | 1 | 56 | 70 | |
Cemophora lineri | 1 | 1 | 12 | 1 | 13 | 14 | |||||
Coluber constrictor | 11 | 11 | 90 | 2 | 92 | 103 | |||||
Coniophanes imperialis | 64 | 64 | 64 | ||||||||
Diadophis punctatus | 1 | 1 | 1 | ||||||||
Drymarchon melanurus | 83 | 83 | 83 | ||||||||
Drymobius margaritiferus | 18 | 18 | 18 | ||||||||
Farancia abacura | 3 | 3 | 3 | ||||||||
Ficimia streckeri | 11 | 11 | 11 | ||||||||
Haldea striatula | 43 | 43 | 43 | ||||||||
Heterodon kennerlyi | 3 | 3 | 3 | ||||||||
Heterodon platirhinos | 3 | 3 | 3 | 15 | 8 | 26 | 29 | ||||
Hypsiglena jani | 7 | 7 | 7 | ||||||||
Lampropeltis annulata | 5 | 5 | 4 | 37 | 15 | 56 | 61 | ||||
Lampropeltis calligaster | 10 | 10 | 10 | ||||||||
Lampropeltis gentilis | 2 | 2 | 2 | ||||||||
Lampropeltis getula complex | 13 | 1 | 14 | 14 | |||||||
Lampropeltis holbrooki | 14 | 14 | 2 | 24 | 26 | 40 | |||||
Lampropeltis splendida | 2 | 2 | 12 | 12 | 14 | ||||||
Leptodeira septentrionalis | 13 | 13 | 13 | ||||||||
Masticophis flagellum | 25 | 61 | 5 | 91 | 12 | 133 | 25 | 3 | 173 | 264 | |
Masticophis schotti | 122 | 122 | 122 | ||||||||
Nerodia clarkii | 43 | 1 | 44 | 3 | 45 | 16 | 64 | 108 | |||
Nerodia cyclopion | 5 | 5 | 5 | ||||||||
Nerodia erythrogaster | 20 | 20 | 20 | ||||||||
Nerodia fasciata | 3 | 3 | 3 | ||||||||
Nerodia rhombifer | 4 | 4 | 163 | 2 | 165 | 169 | |||||
Opheodrys aestivus | 56 | 56 | 56 | ||||||||
Pantherophis emoryi | 19 | 19 | 38 | 161 | 4 | 165 | 203 | ||||
Pantherophis obsoletus | 1 | 1 | 17 | 17 | 18 | ||||||
Pituophis catenifer | 4 | 4 | 79 | 79 | 83 | ||||||
Regina grahami | 7 | 7 | 7 | ||||||||
Rhinocheilus lecontei | 10 | 10 | 10 | ||||||||
Salvadora grahamiae | 2 | 2 | 70 | 70 | 72 | ||||||
Sonora semiannulata | 51 | 51 | 51 | ||||||||
Storeria dekayi | 1 | 13 | 1 | 15 | 188 | 1 | 189 | 204 | |||
Tantilla gracilis | 9 | 9 | 52 | 3 | 55 | 64 | |||||
Tantilla nigriceps | 49 | 49 | 49 | ||||||||
Thamnophis marcianus | 10 | 33 | 43 | 14 | 341 | 8 | 1 | 364 | 407 | ||
Thamnophis proximus | 41 | 413 | 454 | 1 | 519 | 17 | 537 | 991 | |||
Thamnophis sirtalis | 4 | 4 | 4 | ||||||||
Tropidoclonion lineatum | 1 | 1 | 1 | 1 | 2 | ||||||
Elapidae | 113 | 113 | 113 | ||||||||
Micrurus tener | 113 | 113 | 113 | ||||||||
Leptotyphlopidae | 1 | 1 | 102 | 102 | 103 | ||||||
Rena dulcis | 1 | 1 | 1 | 102 | 102 | 103 | |||||
Pythonidae | 1 | 1 | 1 | ||||||||
Python regius | 1 | 1 | 1 | ||||||||
Typhlopidae | 1 | 1 | 2 | 6 | 6 | 8 | |||||
Indotyphlops braminus | 1 | 1 | 2 | 6 | 6 | 8 | |||||
Viperidae | 28 | 10 | 1 | 39 | 7 | 482 | 22 | 1 | 512 | 551 | |
Agkistrodon contortrix | 3 | 3 | 3 | ||||||||
Agkistrodon piscivorus | 106 | 1 | 107 | 107 | |||||||
Crotalus atrox | 28 | 7 | 1 | 36 | 7 | 363 | 3 | 373 | 409 | ||
Sistrurus tergeminus | 3 | 3 | 10 | 19 | 29 | 32 | |||||
Testudines | 292 | 132 | 162 | 586 | 19 | 754 | 18 | 3 | 14 | 808 | 1 394 |
Cheloniidae | 88 | 64 | 35 | 187 | 11 | 1 | 12 | 11 | 35 | 222 | |
Caretta caretta | 2 | 10 | 1 | 13 | 3 | 2 | 1 | 6 | 19 | ||
Chelonia mydas | 81 | 26 | 23 | 130 | 2 | 1 | 4 | 8 | 15 | 145 | |
Eretmochelys imbricata | 2 | 1 | 3 | 4 | 2 | 1 | 7 | 10 | |||
Lepidochelys kempii | 5 | 26 | 10 | 41 | 2 | 4 | 1 | 7 | 48 | ||
Chelydridae | 1 | 1 | 2 | 2 | |||||||
Chelydra serpentina | 1 | 1 | 2 | 2 | |||||||
Dermochelyidae | 1 | 1 | 3 | 3 | 4 | ||||||
Dermochelys coriacea | 1 | 1 | 3 | 3 | 4 | ||||||
Emydidae | 187 | 65 | 109 | 361 | 1 | 405 | 3 | 3 | 2 | 414 | 775 |
Malaclemys terrapin | 34 | 2 | 36 | 36 | |||||||
Pseudemys nelsoni | 7 | 7 | 7 | ||||||||
Terrapene carolina | 2 | 2 | 3 | 3 | 5 | ||||||
Terrapene ornata | 3 | 3 | 29 | 2 | 31 | 34 | |||||
Trachemys scripta | 8 | 8 | 8 | ||||||||
Trachemys scripta elegans | 182 | 65 | 95 | 342 | 1 | 331 | 3 | 1 | 336 | 678 | |
Trachemys scripta scripta | 7 | 7 | 7 | ||||||||
Kinosternidae | 15 | 2 | 17 | 7 | 80 | 87 | 104 | ||||
Kinosternon flavescens | 15 | 2 | 17 | 7 | 80 | 87 | 104 | ||||
Testudinidae | 212 | 1 | 213 | 213 | |||||||
Gopherus berlandieri | 212 | 1 | 213 | 213 | |||||||
Trionychidae | 1 | 17 | 18 | 56 | 56 | 74 | |||||
Apalone spinifera | 1 | 17 | 18 | 56 | 56 | 74 | |||||
Total Amphibians and Reptiles | 1 461 | 2 843 | 600 | 4 904 | 639 | 12 951 | 971 | 47 | 222 | 14 830 | 19 734 |
Eleven amphibian and 36 reptile species occur or have occurred naturally or as introduced or accidental species on North Padre Island (Table
Nine amphibian and 39 reptile species currently occur or historically occurred on Mustang Island. Twenty-one reptile species and four amphibian species occur or have occurred on SPI. In all, there are 47 species of reptiles and 12 species of amphibians that occur or have occurred naturally or as introduced or accidental species on North and South Padre and Mustang islands (hereafter “the South Texas barrier islands” or “the islands”).
By comparison, 31 amphibian species and 93 reptile species occur in the seven counties that include or are adjacent to the barrier islands. Eleven species of amphibians and 22 species of reptiles that occur on the mainland, do not occur on the islands. Seven species of reptiles and one amphibian species that occur on Mustang Island do not occur on the other barrier islands. Five amphibian species and seven reptile species that occur on North Padre Island do not occur on the other islands. Three amphibian species and six reptile species that occur on South Padre Island are not known from the other barrier islands.
Six species recorded during the 2002–2003 surveys were first records of those species from North Padre Island: Pseudacris clarkii (spotted chorus frog), Bufo woodhousii (Woodhouse’s toad), Cemophora lineri (Texas scarletsnake), Pantherophis emoryi (Great Plains ratsnake), Gastrophryne carolinensis (eastern narrow-mouthed toad), and Hyla squirella (squirrel tree frog). Subsequently, in coordination with staff at PINS, I confirmed four more species not previously known from North Padre Island: Rana sphenocephala (southern leopard frog), Chelydra serpentina (common snapping turtle), Rena dulcis (plains threadsnake), and Bufo nebulifer (gulf coast toad). The records for R. sphenocephala, B. woodhousii, G. carolinensis, and C. serpentina were the first records for Kleberg County (
The species accounts that follow characterize and enumerate records for each current, past, or potential species or subspecies that occur, possibly occur, or were previously thought to occur, on Padre and Mustang islands. Specimens contained in museum collections, iNaturalist observations, and records based on verifiable photos are included. Audio recordings are included as Suppl. materials.
Results from this inventory (2002–2021) are compared to a checklist of amphibians and reptiles of PINS (only PINS;
Order Anura
Family Bufonidae
There are six museum specimens of B. nebulifer from NPI, with imprecise locality information, collected in 1891 (USNM 45349–52 and 46150). Our team did not detect B. nebulifer during the 2002–2003 surveys.
Bufo nebulifer breeds in ephemeral pools and wetlands but may be found in much drier habitats and under artificial lighting. The one specimen photographed during this inventory was found in the parking lot of the Malaquite Visitor Center within PINS.
Eight Anurans found on North Padre Island a Bufo woodhousii (Woodhouse’s toad) b Bufo nebulifer (Gulf Coast toad; photograph by Alicia Walker) c Gastrophryne carolinensis (eastern narrow-mouthed toad) d Hyla cinerea (Green treefrog) e Hyla squirella (squirrel treefrog) f Pseudacris clarkii (spotted chorus frog) g Rana berlandieri (Rio Grande leopard frog) h Scaphiopus hurterii (Hurter’s spadefoot).
The first record for B. woodhousii from NPI and Kleberg County was collected during the 2002–2003 surveys. Another specimen collected in 2004 was the basis for a Kleberg County record published by
Three specimens from Mustang Island in the TCWC collection were identified as hybrids of B. woodhousii and B. speciosus (TCWC 93746-48) by the collector (J. K. Baker). I examined those specimens and observed that two of the specimens have weak cranial crests, which are rarely, and then only indistinctly, present in B. speciosus but always present in B. woodhousii; one of the specimens appears to have a faint mid-dorsal stripe, which is rarely and then only weakly present in B. speciosus, but usually present in B. woodhousii. While these characteristics provide some morphological support for Baker’s identification, the specimens fall within the range of variation for B. speciosus. Because B. woodhousii is not known from Mustang Island, hybrids are unlikely, but it is possible that B. woodhousii was extirpated before any observations were recorded.
Inst Code | Cat # | Scientific Name | Date | County | Locality | Collector/observer |
---|---|---|---|---|---|---|
BUMMC | R 19809 | Bufo woodhousii | 10.9.1941 | Kenedy | Armstrong | Brown, Bryce C. |
TCWC | 20830 | Bufo woodhousii | 11.4.1965 | Brooks | 12 mi SW Falfurrias | THS Field Meet |
|
A174386 | Bufo woodhousii | 2.7.1966 | Kenedy | 4.5 mi S Riviera | Ernest A. Liner & L.D. Wilson |
|
A183140 | Bufo woodhousii | 8.4.1968 | Kenedy | 3.4 mi N Armstrong on US Hwy 77 | Allan H. Chaney |
|
A183141 | Bufo woodhousii | 8.4.1968 | Kenedy | 3.4 mi N Armstrong on US Hwy 77 | Allan H. Chaney |
|
A183142 | Bufo woodhousii | 8.4.1968 | Kenedy | 3.4 mi N Armstrong on US Hwy 77 | Allan H. Chaney |
UTA | 8382 | Bufo woodhousii | 8.8.1975 | Cameron | Near San Benito | 1, J. L. Darling |
UTA | 8383 | Bufo woodhousii | 8.8.1975 | Cameron | Near San Benito | 1, J. L. Darling |
INAT | 13049736 | Bufo woodhousii | 29.10.2015 | Kenedy | Kenedy County (obscured) | Bryan Calk |
KU | 294840 | Bufo woodhousii | na | Cameron | Brownsville | J.C. Lee |
During the 2002–2003 surveys, I made several audio recordings of G. carolinensis (Suppl. material
There were no records for G. olivacea for the South Texas barrier islands until a photo was posted on iNaturalist in 2017 (https://www.inaturalist.org/observations/3447802; photo voucher
This species was once found mostly in northeastern Mexico and in the Rio Grande Valley of Texas but has expanded its range to include isolated populations in southern Louisiana and most of the eastern third of Texas to the Red River. It is often found in plants and other items transported from the Rio Grande Valley (
Eleutherodactylus planirostris is native to Cuba, the Bahamas, the Cayman Islands, and the Turk and Caicos Islands (
Osteopilus septentrionalis is native to the Bahamas, Cayman Islands and Cuba and has been introduced to other Caribbean Islands, most of Florida, and is spottily distributed in coastal areas from Georgia to Texas (
During and after rains during warmer months in 2002 and 2003 our team recorded conspicuous choruses of H. cinerea at all calling-frog stations and collected one of the 14 museum specimens from NPI. The historical record indicates that the species is considerably less common in other years.
The status of this species in southern portion of the study area is unclear. I heard choruses of H. cinerea at The Nature Conservancy’s Southmost Preserve, in Cameron County, in 2002. There are ten museum specimens from Cameron County but no iNaturalist records. There are 34 museum specimens and zero iNaturalist observations from Kenedy County. The newest specimen from Cameron County was collected in 1941, and the newest specimen from Kenedy County was collected in 1976. The only record of any kind from the mainland portion of the counties south of Nueces County is an iNaturalist audio recording made in 2015 near Port Mansfield in Willacy County: https://www.inaturalist.org/observations/1480951. The status of the species in southern Texas deserves further study.
There were no records for H. squirella from NPI until I photographed and audio recorded it during the 2002–2003 surveys. The calls were recorded in emergent wetlands during breeding season (Suppl. material
There is still only one mainland museum record collected from the study area south of Kleberg County of a specimen taken near Port Mansfield, in Willacy County in 2015. That specimen was also posted to iNaturalist where the collector commented that it was a single individual calling from a roadside ditch. The 28 museum records from Cameron County were all from a small area in the urbanized portion of southern SPI.
Our team did not observe or hear P. clarkii in 2002, but in 2003 I made audio recordings and collected a specimen (TCWC 93884) in temporarily flooded grasslands during drought-ending tropical rains. That specimen remains the only specimen of P. clarkii collected from the South Texas barrier islands, and among the eight research grade iNaturalist observations, the only observation based on a photo (https://www.inaturalist.org/observations/12007443). The species is not known from museum or iNaturalist records from SPI or Mustang islands. Only 18 of the 231 museum specimens from the study area have been collected since 1990.
There are seven museum specimens of R. berlandieri from NPI and three from Mustang Island residing in the collections I surveyed. I found 584 specimens from the mainland portion of the seven counties. During the 2002–2003 surveys, I collected two specimens and audio-recorded the species at most ephemeral and man-made ponds in the 24 km south of Packery Channel.
I collected one specimen that was particularly noteworthy because of its locality: TCWC 93885 was collected ~ 80.5 km south of the southern end of Park Road 22. That locality is a narrow, arid, and sparsely vegetated part of the island between two wash-over channel depressions that sometimes hold freshwater but are periodically flooded with saline water from the Gulf of Mexico and hypersaline water from the Laguna Madre. Permanent or long-lasting freshwater, usually associated with R. berlandieri, is not present. When I last visited that site in June 2018, the ponds only supported halophytic vegetation around its edges, which were crusted with salt. The survival strategies and dynamics of that population segment deserve further study.
A 2018 iNaturalist observation, based on an audio file, is the first and only record of Rana catesbeiana on NPI (https://www.inaturalist.org/observations/8027494). Other experienced listeners have concurred on the identification of that call, but because of the poor quality of the recording, I cannot confirm with complete certainty that the call is that of R. catesbeiana. The NPI record is from the northern tip of the island, near Packery Channel. The species is relatively common in Aransas, Nueces, and San Patricio counties and much of the United States but uncommon in the counties adjacent to Padre Island. There were 77 museum specimens from the seven counties. The species requires relatively permanent freshwater for its long-lived larvae, therefore its habitat on NPI is probably limited to several small man-made ponds within the urbanized northernmost part of the island and three manmade ponds in the northern part of the Padre Island National Seashore. The lake that occurs near the middle of the island, from ~ 22.5 km south of Packery Channel to ~ 27 km south of Packery Channel is periodically dry but, in some years, might hold water long enough for R. catesbeiana reproduction. There is little to no habitat for the species in the southern 143 km of Padre Island. The species is a non-native and invasive in the western United States, where it competes with and preys on native fauna. Its recent arrival on North Padre and Mustang islands might be considered invasive.
There is one Rana sphenocephala specimen from Padre Island (
Dorsolateral ridges inset posteriorly at the groin in R. berlandieri usually distinguish it from R. sphenocephala, but dorsolateral ridges of some Rana specimens from NPI are not distinctly inset. We examined many specimens in the field and could never say that any of them were distinctly typical of R. sphenocephala. While morphological differences between the species were not consistently differentiating, their calls are quite different and perhaps better evidence of their occurrence on the island than specimens or photos. The audio file of R. sphenocephala calling may also include R. berlandieri calling at the same time.
I did not find verifiable records of Scaphiopus couchii from the South Texas barrier islands. It is mentioned here because
I located 30 museum specimens from NPI, nine of which were collected during the 2002–2003 surveys. I found five museum specimens from Mustang Island and 235 from the mainland portion of the seven counties. There are 61 iNaturalist observations from NPI, one from Mustang Island and none from South Padre Island. Scaphiopus hurterii was captured 34 times during the 2002–2003 surveys at four study sites, all in flooded grasslands within grassland/wetland matrices. It was audio-recorded at every stop on the calling-frog survey route. The species is conspicuous during and after rains but nearly undetectable by the casual observer during dryer times.
Order Testudines
Padre Island National Seashore Division of Sea Turtle Science and Recovery has conducted a sea turtle monitoring, research, and recovery program since the 1970s (https://www.nps.gov/pais/learn/seaturtles.htm). The program is centered around monitoring and recovery of Kemp’s Ridley Sea Turtle (Lepidochelys kempii) but has recorded the presence of four additional species: Loggerhead Sea Turtle (Caretta caretta), Green Sea Turtle (Chelonia mydas), Leatherback Sea Turtle (Dermochelys coriacea), Hawksbill Sea Turtle (Eretmochelys imbricata). Dozens of staff and volunteers patrol the beaches for Kemp’s Ridley nests each summer. Eggs are excavated and hatched in the lab. Hatchling releases, which usually occur from June-August each year, are popular public events. I was not charged with conducting field surveys for sea turtles, but we did occasionally encounter sea turtles on the beach, including the Hawksbill Sea Turtle shown in Figure
Sea turtle iNaturalist and museum records from the South Texas barrier islands. MI = Mustang Island; NPI = North Padre Island; SPI = South Padre Island iNat = iNaturalist observation (accessed 06 Oct 2020); Mus = Museum Specimens (Vertnet.org, accessed 02 Oct 2020).
iNaturalist Observations | Museum Specimen Records | All Totals | ||||||||
---|---|---|---|---|---|---|---|---|---|---|
MI | NPI | SPI | iNatTot | MI | ML | NPI | SPI | MusTot | ||
Cheloniidae | 88 | 64 | 35 | 187 | 11 | 1 | 12 | 11 | 35 | 222 |
Caretta caretta | 2 | 10 | 1 | 13 | 3 | 2 | 1 | 6 | 19 | |
Chelonia mydas | 81 | 26 | 23 | 130 | 2 | 1 | 4 | 8 | 15 | 145 |
Eretmochelys imbricata | 2 | 1 | 3 | 4 | 2 | 1 | 7 | 10 | ||
Lepidochelys kempii | 5 | 26 | 10 | 41 | 2 | 4 | 1 | 7 | 48 | |
Dermochelyidae | 1 | 1 | 3 | 3 | 4 | |||||
Dermochelys coriacea | 1 | 1 | 3 | 3 | 4 |
Eight reptiles that occur on North Padre Island a Eretmochelys imbricata (Hawksbill sea turtle) b Chelydra serpentina (common snapping turtle) c Malaclemys terrapin (diamondback terrapin) d Trachemys scripta (pond slider) e Ophisaurus attenuatus (slender glass lizard) f Hemidactylus turcicus (Mediterranean house gecko) g Holbrookia propinqua (keeled earless lizard) h Phrynosoma cornutum (Texas horned lizard; photograph by Jerry Batey).
A photo taken by a PINS staff member in 2007 (
There were no specimens or iNaturalist observations of M. terrapin from the South Texas barrier islands until one juvenile was collected, and another juvenile was photographed in an urbanized part of southernmost South Padre Island in February and March 2019 (
There were three T. carolina museum records from the mainland portion of the study area and two iNaturalist observations from Mustang Island. The mainland occurrences are individual records separated by decades (Suppl. material
There are no museum specimens of T. ornata from the South Texas barrier islands and no records of any kind from NPI or SPI. Three iNaturalist observations from Port Aransas on Mustang Island have been entered since 2013.
Trachemys scripta is easily observed on any visit to the three manmade ponds within the Padre Island National Seashore. Our team trapped 24 pond sliders in hoop traps in those ponds. No other turtle species were observed. Trachemys scripta was photographed but not collected. I located four museum specimens from NPI, two from Mustang Island, and 287 from the adjacent counties. Trachemys scripta from the study area is usually assigned to the subspecies T. s. elegans (red-eared slider), but there are seven iNaturalist observations (several of which appear to be the same individual) identified as T. s. scripta (yellow-bellied slider) from the South Padre Island Birding and Nature Center at the southern tip of SPI. The yellow-bellied slider is native to the eastern half of the US, but both subspecies have established introduced populations all over the US and Europe.
Several occurrences of Gopherus berlandieri on the South Texas barrier islands have been recorded, but there is little evidence that suggests the occurrences are natural. One specimen of a G. berlandieri (
Little habitat for G. berlandieri is present on the South Texas barrier islands, and I could find only two reports of naturally occurring tortoises on deep sand:
Order Crocodilia
Family Alligatoridae
There are no museum records from the South Texas barrier islands and only two from the seven counties, but the museum database is not a good indicator of the abundance an animal whose adult length may be 1.8–5 m (
Just prior to the 2002–2003 surveys, NPS had introduced three A. mississippiensis to a manmade pond within PINS according to the Natural Resource Manager at the time (Darrel Echols, pers. comm.). In consultation with experts, NPS later determined that alligators had probably never occurred naturally on the island and removed them. In 2007 an individual was found on Big Shell Beach, ~ 40 km south of the southern end of Park Road 22. That animal had been tagged ~ 500 km away, across the Gulf of Mexico at a national wildlife refuge in Louisiana (Buzz Botts, National Park Service, pers, comm.). I added that observation to iNaturalist (https://www.inaturalist.org/observations/20228712), which is the only iNaturalist observation on NPI. Then in 2021, PINS reported on their Facebook page that another alligator washed up on NPI which had also been tagged in Louisiana https://www.facebook.com/FriendsPINS/posts/173996127976128). Those occurrences provide support for the hypothesis that Gulf of Mexico currents play a role in the transport of out-of-range species to the South Texas barrier islands. Alligators will survive in manmade ponds for years, but natural populations require marshy habitat with access to deeper fresh or brackish water (
Ophisaurus attenuatus is one of the most frequently observed reptiles on NPI. I located 17 museum specimens and 1012 iNaturalist observations. During the 2002–2003 surveys, the species was trapped 14 times at all eight study sites between the north end of PINS and the 35-mile-marker. A phenomenon resembling a mass movement of glass lizards was reported on iNaturalist from 24 February to 20 June 2017, when Jon McIntire of Corpus Christi, Texas, reported 938 observations, mostly on Park Road 22 and Bird Island Basin Road on NPI. He reported that the surrounding grasslands had recently been control-burned. The species is less frequently seen on Mustang Island, with five iNaturalist observations and 16 museum specimens. There is only one iNaturalist record and no museum records for the species on SPI; potential observers on SPI rarely venture into the island far from the beach, so the species is probably more common on SPI than that single record might imply. There were 91 museum records from the mainland portion of the seven counties.
Hemidactylus turcicus is an introduced species native to the Mediterranean region. The earliest specimens I found from Texas were collected in Cameron County in 1953 (
Holbrookia propinqua is probably the most abundant reptile on the South Texas barrier islands, certainly the most observable. I located 724 museum specimens from NPI and 1916 specimens from the seven counties. During the 2002–2003 surveys, it was trapped 93 times. Another 128 observations were recorded, and hundreds of casual observations by the survey team were not recorded. On NPI, it is most abundant in the back beach/foredunes ecological zone, but it is common on deep dry sand throughout the island. A primary component of H. propinqua habitat is deep sand, which is the primary soil component on the islands and of an ~ 800,000 ha area that extends westward from the Land Cut and includes parts of several counties in southern Texas. That area, commonly known as the Sand Sheet, has been altered by grazing, farming, and invasive, nonnative, grasses, mostly Kleberg bluestem (Dichanthium annulatum) and buffelgrass (Pennisetum ciliare), which has led to its decline on the mainland.
The catalogue of reptiles and amphibians for the collection kept at Texas A&M, Kingsville (TAMUK) contained an entry for H. (lacerata) subcaudalis (TAMUK 1879) collected in 1968 from the “Dunn Ranch” on NPI, but that specimen was missing when I examined the collection in 2002 and missing when the collection was transferred to
The questionable Dunn Ranch specimen was the only specimen of that species from the South Texas barrier islands.
Both H. lacerata and H. subcaudalis have been the focus of a considerable amount of survey work and research following a 2011 ruling by the U. S. Fish and Wildlife Service that a listing of threatened or endangered, pursuant to the Endangered Species Act of 1973, may be warranted.
Four species of Sceloporine lizards are known from the mainland portion of the seven counties: Sceloporus consobrinus (prairie lizard), S. olivaceus (Texas spiny lizard), S. variabilis (rosebellied lizard), and S. cyanogenys (blue spiny lizard). No Sceloporine lizards are known from NPI or Mustang Island, but a specimen of S. olivaceus was collected on South Padre Island in 1916 (
Anolis carolinensis is an abundant fixture of urban backyards and woodlands throughout the southeastern United States. There are no museum records from NPI and only two from Mustang Island but there are iNaturalist records from all urbanized areas of the South Texas barrier islands. Across its range, A. carolinensis is rarely observed in undeveloped areas and is probably absent from undeveloped portions of the islands due to lack of perching structures. I found 84 museum records from the seven counties.
Anolis sagrei is another mostly urban species, native to Cuba and The Bahamas. It was first collected in the United States in Florida in 1935. The first records from Texas were specimens collected in Cameron County in 1986. I found nine museum specimens from the seven counties and 637 iNaturalist observations from the islands since 2009. One hundred nine of those came from NPI, all from the urbanized northern tip of the island.
Our team captured P. obsoletus ten times at five different localities from near the northern boundary of PINS to 56 km down the island, in wetlands, xeric grasslands, and dunes. We collected three specimens. There were seven specimens from NPI in museums and 47 specimens from the seven counties but none from South Padre or Mustang Islands. There is one iNaturalist record for Mustang Island based on a photo taken in 1985 (https://www.inaturalist.org/observations/2578244).
Eight reptiles that occur on North Padre Island a Plestiodon obsoletus (great plains skink b Scincella lateralis (little brown skink) c Aspidoscelis sexlineatus (six-lined racerunner) d Coluber constrictor (North American racer) e Heterodon platirhinos (eastern hognose snake) f Lampropeltis triangulum annulata (Tamaulipan milksnake) g Masticophis flagellum (coachwhip) h Nerodia rhombifer (diamondback watersnake).
I located four museum specimens and 31 iNaturalist observations of S. lateralis from NPI and two museum specimens and only one iNaturalist record from Mustang Island. There are no records from SPI. I found 82 museum specimens from the seven counties. Our team captured S. lateralis at seven localities from the northern boundary of PINS to 56 km down the island. All except one of the observations were in moist grasslands/wetlands. The exception was an individual that was trapped at study site 11, which was in sparsely vegetated foredunes.
In earlier versions of their online list, NPS had listed Plestiodon septentrionalis (prairie skink) as a species that occurs on PINS mostly based on a specimen in the NPS vertebrate collection (formerly PAIS 2025; now TCWC 93804) that had been identified as P. septentrionalis but has since been reidentified as S. lateralis. There is no evidence that the P. septentrionalis occurs on the barrier islands but no reason to think that it might not.
Aspidoscelis gularis was classified as “uncommon” by
Aspidoscelis sexlineata was captured and photographed 46 times. Team members recorded another 16 observations during visual encounter surveys and made many more casual observations. I located 24 specimens in museum collections from NPI, eighteen from Mustang Island, five from South Padre Island, and 145 specimens from the mainland. The species was observed in the back-beach, foredunes, grasslands, emergent wetlands, and dunes.
iNaturalist recognizes the taxon, but no observations of A. s. stephensae have been entered, while 12 specimens have been identified as A. sexlineata within the taxon’s purported range as defined by
I found eight museum specimens of Arizona elegans from NPI, six from Mustang Island, and one from SPI (as of 08 October 2020). Another iNaturalist observation from SPI was entered in April 2021 and was deposited into the
I collected one road-killed C. constrictor (TCWC 93867) on Park Road 22, north of PINS where it passed through a flooded grassland/wetland. A team member observed one on the beach ~ 3 km south of the southern end of Park Road 22. Figure
I found one museum record for the islands (TAMUK 5526), a road-killed snake collected on Park Road 22, just north of the PINS entrance station. That specimen is among numerous specimens from the TAMUK collection (later moved to
Our team collected two road-killed specimens (TCWC 93872, TCWC 93873) and captured and examined three others during the 2002–2003 surveys. The road-killed specimens were surrounded by a grassland/wetland matrix. The trapped specimens were all from one location which was in a transition zone between sparsely vegetated foredunes and a more densely vegetated grassland on deep but stable sand. Photos of three of those specimens are the only iNaturalist records for the species from the South Texas barrier islands. There are eight museum specimens from NPI prior to the 2002–2003 surveys but no records of any kind from the South Texas barrier islands after that.
There are no records for Lampropeltis getula from NPI or SPI. One specimen from NPI (
Our team observed four L. triangulum and took two as specimens (TCWC 93878, 93879) during the 2002–2003 surveys. Those observations were all within the grassland wetland matrix. Following the taxonomic arrangement prevalent at the time (
Masticophis flagellum was the most observed and most captured snake species during the 2002–2003 surveys. It was trapped 21 times at seven study sites, which spanned 94 km and four ecological zones: grasslands, emergent wetlands, sparsely vegetated foredunes, and dune/swell complexes. from Study Site 1 near Bird Island Basin to Study Site 17, near the Mansfield Channel. I took one specimen (TCWC 93880). There were 25 museum specimens from NPI, thirteen from Mustang Island, and 148 from the seven counties. There are 61 iNaturalist observations from NPI, 25 from Mustang Island, and five from SPI.
Nerodia rhombifer was observed four times and captured once near the man-made pond along the road to Bird Island Basin. There were two museum specimens from NPI and none from Mustang Island. There are four iNaturalist record for NPI, and none from Mustang Island. I found 163 specimens from the mainland portion of the seven counties. Mostly a fish eater and dependent on permanent fresh water, the species is probably only found on the northern end of NPI in and around the several manmade ponds.
Nerodia clarkii is regularly observed along the shorelines of Nueces, Corpus Christi, and Oso bays, and Mustang Island, but an iNaturalist observation of a road-killed specimen, near the northern end of NPI, just south of the Nueces County line, is the only verifiable occurrence of the species on NPI or in Kleberg County (https://www.inaturalist.org/observations/8105046). There are 33 iNaturalist observations and 18 museum records from Mustang Island. Forty-three more museum specimens have been taken around Corpus Christi Bay, in the counties of Nueces, San Patricio, and Aransas. The southern edge of the range of the species is an elastic boundary where the brackish water of Corpus Christi Bay meets the hypersaline water of the Laguna Madre. Nerodia clarkii could enter the upper Laguna Madre when higher precipitation lowers salinity, then retreat into Corpus Christi Bay when salinity rises, an example of “behavioral osmoregulation” (Dunson and Mazzotti, 1989).
There is only one record for Cemophora lineri from NPI or the South Texas barrier islands, an individual I captured in a grassland near the mid-point between the end of Park Road 22 and the Mansfield Channel in 2002 (photo voucher,
Comparison of Cemophora lineri (Texas scarletsnake) specimen from North Padre Island with C. lineri specimen from San Patricio County a Cemophora lineri (Texas scarletsnake) from North Padre Island b Cemophora lineri from San Patricio County. Note that the colors of the NPI specimen are duller than those of the scarletsnake from the mainland.
In addition to their genetic work,
As it is with other reptiles and amphibians on NPI, the colors of the C. lineri I photographed on NPI are duller than those of other C. lineri I have observed in the study area on the mainland. Figure
During the 2002–2003 surveys, our team collected two road-killed P. emoryi of the four NPI specimens in museum databases (
Eight reptiles that occur on North Padre Island a Pantherophis emoryi (Great Plains ratsnake) b Tantilla gracilis (flathead snake) c Thamnophis marcianus (checkered garter snake) d Thamnophis proximus (western ribbon snake) e Tropidoclonion lineatum (lined snake) from South Bird Island, just offshore of NPI f Rena dulcis (Texas threadsnake; PINS file photo) g Crotalus atrox (western diamond-backed rattlesnake) h Sistrurus tergeminus (western massasauga).
I found no museum specimens of P. catenifer from the barrier islands, but an iNaturalist record of a 2006 observation (https://www.inaturalist.org/observations/2580986) was entered in 2016. Subsequently, three iNaturalist observations from the northernmost, urbanized part of the island, were entered for snakes observed in 2015, 2019, and 2020.
There is one 1982 museum specimen of S. dekayi from NPI, which is the only specimen from the South Texas barrier islands. Our team did not detect the species during the 2002–2003 surveys. There are now 13 iNaturalist records from NPI, one from Mustang Island, and one from SPI. I found 188 museum specimens from the inland portion of the seven counties.
Tantilla gracilis is largely fossorial, thus rarely observed, so they are probably more common on NPI than the three museum specimens and nine iNaturalist observations suggest. During the 2002–2003 surveys, our team captured three T. gracilis (TCWC 93900) at three study sites, all within the grassland/wetland matrix. There are no records for Mustang or South Padre islands. I found 52 T. gracilis museum specimens from the inland portion of the seven counties.
Thamnophis marcianus is common and conspicuous across most of its range. Our team observed this species three times. One road-killed specimen (TCWC 93901) was collected. I found eight museum specimens from NPI, fourteen from Mustang Island, one from Harbor Island (near Port Aransas), and 327 records from the inland portion of the seven counties. There are ten iNaturalist observations for Mustang Island and 33 from NPI. All observations are closely associated with wetlands and ponds within the grassland/wetland matrix. Its distribution is probably limited by the availability of freshwater to the northern 27 km of the island.
During the 2002–2003 survey our team captured Thamnophis proximus four times and collected six road-killed specimens (TCWC 93902–93908). All observations were closely associated with emergent wetlands within the grassland/wetland matrix.
A single museum specimen of Tropidoclonion lineatum (
Rena dulcis is known from the South Texas barrier islands from one photo taken by PINS staff in 2010. That snake was uncovered ~ 46 cm underground while digging a hole for a fence post. There is an iNaturalist record from the north end of Mustang Island, but the photo submitted with that record is not detailed enough to determine with certainty if the snake is R. dulcis or the non-native Indotyphlops braminus (Brahminy threadsnake; https://www.inaturalist.org/observations/1270983). There are 101 museum records from the seven counties. Rena dulcis is fossorial and not easily observed, so it is probably more common on NPI (and possibly Mustang Island) than the sparse historical record implies.
During the 2002–2003 surveys, out team captured five S. tergeminus. I located 19 museum specimens and three iNaturalist records from NPI but no records from Mustang or South Padre islands. There are ten museum specimens and one iNaturalist observation from the mainland portion of the seven counties.
Given the dynamic nature of barrier island geomorphology and the resulting equally dynamic arrangement of ecological zones, it is not surprising to find evidence of fluctuations in the occurrence and abundance of herpetofauna over the time-period for which we have records. Some species said to be abundant in the historical record were found to be rare or absent during all or part of this study period (2002–2020), and some species found to be abundant during the study period were absent or sparsely represented in the historical record. In some cases, failure to observe a species for decades has led me to presume they have been extirpated. The variability between time periods is particularly evident for Bufonids (true toads).
Non-marine species that are extirpated from islands may later repopulate naturally despite the ecological barrier posed by saltwater.
Several species found on NPI differ in relative abundance and/or morphology from their mainland counterparts. Padre Island herpetofauna are generally paler than mainland specimens; in particular, B. woodhousii, M. flagellum, and the great plains ratsnake (Pantherophis emoryi) found on the island exhibit a ground color that is often nearly white, and the reds and yellows of the Texas scarletsnake (Cemophora lineri) that we observed were duller than its mainland counterpart. The ventral scale row count of one C. lineri specimen was found to be outside of the range of variation for that species but within the range of variation and near the mean for C. c. coccinea (this may be a single aberrant individual). The only Ranid found in the mainland counties adjacent to Padre Island is the Rio Grande leopard frog (Rana berlandieri), while both R. berlandieri and R. sphenocephala are found on NPI. The external morphology of some Ranid specimens found on North Padre Island are intermediate between R. berlandieri and R. sphenocephala, therefore calls are the most definitive record of occurrence for those species (Suppl. material
Several non-native species of amphibians and reptiles have established breeding populations in southern Texas. Two non-native lizards, the Mediterranean gecko (Hemidactylus turcicus) and the brown anole (Anolis sagrei) have well-established populations in southern Texas, including many records from the South Texas barrier islands. Anolis sagrei are known to displace native green anoles (A. carolinensis). iNaturalist records have been posted for the Cuban treefrog (Osteopilus septentrionalis) on the southern end of South Padre Island. There are no other records for that species within 480 km of Corpus Christi, Texas, but the species is well-established in Florida and along the Gulf Coast. The invasion of Florida by Cuban treefrogs has severely impacted native ecosystems and has led to localized extirpations of other frogs in urban areas (
There were a few species that appeared on previous checklists for NPI that our team did not detect. While it is unlikely that any of the unconfirmed species occur in abundance, it is possible that some of the species may yet be found on the island. The Texas coral snake (Micrurus tener) probably appeared on previous checklists of North Padre Island herpetofauna (
The basic methodology of the 2002–2003 study was completed by the US National Park Service in consultation with their partners prior to my being tasked with coordinating the inventory There were some things I wish I could have done differently. In short, the original design called for random selection of study sites, where we would conduct drift-fence/pitfall trapping in the spring and early summer only. It is standard practice to employ a random sampling scheme in hopes that future researchers will be able to mimic the methodology, but this study area is 50,000 ha, it extends for 122 km, resources were limited, and the primary objective was to determine presence/absence. The freedom to directly target specific species in specific areas at specific times, should have been a primary component of the plan. Random selection, stratified by ecological zones and geography, also caused study areas to be unevenly distributed within stratifications, leaving some gaps that were under-sampled. While spring sampling is a standard feature of most amphibian and reptile and monitoring plans in much of the United States, in coastal southern Texas, where more than 30% of rainfall usually occurs in September and October, a more effective plan would have specified that some drift-fence/pitfall trapping would occur in the fall. While we did continue with visual encounter and calling-frog surveys throughout the year, we were only allowed to conduct drift-fence/pitfall trapping in the spring and early summer.
The US National Park Service at Padre Island National Seashore (NPS) was instrumental in funding, permitting, and assisting with various components of the project; I owe a special debt of gratitude to several NPS staff, including Travis Clap, Donna Shaver, Wade Stablein, Alicia Walker, Darrel Echols, and especially William “Buzz” Botts. Thanks to the numerous people who braved the harsh conditions of the barrier island to assist in the field, including Lynne Duran, Mark Gallyoun, Kristi Fazioli, Brent Koza, Dimitria Guerrero, Brianna Young, Nicki Hayes, Rod Miller, and Lisa Williams. I owe thanks to numerous professional herpetologists and naturalists who contributed their expert opinions and knowledge to the project, including Frank Judd, Allan Chaney, Jim Dixon, Graham Hickman, Ralph Axtell, Michael Forstner, and Nancy Rabalais. Collection curators who provided data are too numerous to mention, but I owe special thanks to Charles Dardia (CUMV), Linda Ford, David Dickey, and David Kizirian (
Museum and iNaturalist records for Aransas, Cameron, Kenedy, Kleberg, Nueces, San Patricio, and Willacy counties, Texas, and iNaturalist records for North and South Padre and Mustang islands, Texas
Data type: Collections.
Explanation note: This is an excel file containing attributes of all museum and iNaturalist records for Aransas, Cameron, Kenedy, Kleberg, Nueces, San Patricio and Willacy counties, Texas, including North and South Padre and Mustang islands.
Gastrophryne carolinensis calling, 08 July 2003.
Data type: Sound file.
Explanation note: Audio of Gastrophryne carolinensis calling on the night of July 8, 2003.
Hyla squirella calling 08 July 2003
Data type: Sound file.
Explanation note: Audio of Hyla squirella calling on the night of July 8, 2003.
Rana sphenocephala and possibly R. berlandieri calling, 10 February 2013
Data type: Sound file.
Explanation note: Audio of Rana sphenocephala and possibly R. berlandieri calling on the night of February 10, 2013.