An International Borderland of Concern

136 Pages·2016·9.32 MB·English

Prepared in cooperation with the U.S. Fish and Wildlife Service and Oklahoma State University
An International Borderland of Concern: Conservation of
Biodiversity in the Lower Rio Grande Valley
Scientific Investigations Report 2016–5078
U.S. Department of the Interior
U.S. Geological Survey
Front cover. Photographs of Amazilia yucatanensis (buff-bellied hummingbird), Falco femoralis septentrionalis (northern aplomado falcon),
and Leopardus pardalis albescens (northern ocelot). Used with permission and modified from ©Larry Ditto Nature Photography.
Back cover. Photograph of Aythya americana (redheads). Used with permission and modified from ©Larry Ditto Nature Photography.
Lower banner artwork, Biological Report 88(36), November 1988, U.S. Fish and Wildlife Service.
An International Borderland of Concern:
Conservation of Biodiversity in the
Lower Rio Grande Valley
By David M. Leslie, Jr.
Prepared in cooperation with the U.S. Fish and Wildlife Service and
Oklahoma State University
Scientific Investigations Report 2016–5078
U.S. Department of the Interior
U.S. Geological Survey
U.S. Department of the Interior
SALLY JEWELL, Secretary
U.S. Geological Survey
Suzette M. Kimball, Director
U.S. Geological Survey, Reston, Virginia: 2016
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Suggested citation:
Leslie, D.M., Jr., 2016, An international borderland of concern—Conservation of biodiversity in the Lower Rio
Grande Valley: U.S. Geological Survey Scientific Investigations Report 2016–5078, 120 p., http://dx.doi.org/10.3133/
sir20165078.
ISSN 2328-031X (print)
ISSN 2328-0328 (online)
ISBN 978-1-4113-4060-2
iii
Acknowledgments
Funding for this project was provided by the U.S. Fish and Wildlife Service
(USFWS) under Cooperative Agreements 20181J848 and F13AC00484 to
Oklahoma State University. I am extremely grateful to Bryan R. Winton,
Refuge Manager of the Lower Rio Grande Valley National Wildlife Refuge
(NWR), for financial and logistical support of this project. Without a
doubt, this report is richly supported by many superb photographs by Larry
Ditto, former Project Leader of the Lower Rio Grande Valley and Santa
Ana NWRs; his willingness to share these photographs that so perfectly
capture the variety and color of the Lower Rio Grande Valley is greatly
appreciated. Gwyn Carmean also permitted use of her seagrass images.
My sincere thanks are extended to Professor Timothy Brush with the
University of Texas-Pan American and Sonja Jahrsdoerfer, Project Leader
at the Lower Green River NWR Complex and senior author of note on the
original 1988 USFWS report, for their thorough critiques of this synthesis.
I am also very grateful for input from the USFWS staff at the South
Texas Refuge Complex, including Bob Barry, Gisela Chapa, Imer De La
Garza, Chris Hathcock, Rob Jess, Marion Mason, Kelly McDowell, Chris
Perez (particularly for his exceptional editing of multiple drafts of this
report), Mitch Sternberg, Hilary Swarts, and Kim Wahl-Villarreal; Willy
Cupit, Texas Parks and Wildlife Department; Oklahoma State University
colleagues and support staff, including Shannon Brewer, Richard Dolman,
Renee Flasch, Jim Long, Sheryl Lyon, and Cheryl McKnight; and Kevin
Whalen, U.S. Geological Survey (USGS) Cooperative Research Units
Program. Particular thanks to Vince Cavalieri (USFWS East Lansing
Ecological Services Field Office) who assisted me early on with literature
searches and preliminary organization of some sections of the report,
Jesse Burton (National Park Service Natchez Trace Parkway) and Jim
Long who drafted the maps in this report, Donna Shaver (National Park
Service Padre Island National Seashore) who shared current information
and her expertise on sea turtles in the Gulf of Mexico, and Erin Fernandez
Photography (sUtaStFuWs iSn AArriizzoonnaa .E Tchoelo Ogikclaalh Somerav iCceoso pOefrfaicteiv) ew Fhisoh c aonmdm Weniltdeldif eo nR eosceealortc h
Nature UConnits (eOrvkalathioonm, aU SSGtaSte, UUSnFivWerSs,i tayn, dO Wklailhdolimfea MDeapnaargtemmeennt to Ifn Wstiitludtlief)e
©Larry Ditto provided technical support during the preparation of this synthesis.
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Contents
Abstract ...........................................................................................................................................................1
Introduction.....................................................................................................................................................1
Original Report and Its Impact ............................................................................................................1
Need for Updated Compilation ...........................................................................................................2
Survey of LRGV-centric Literature since 1988 .................................................................................4
Report Objectives..................................................................................................................................4
Unique Aspects of the Lower Rio Grande Valley ......................................................................................6
General Description..............................................................................................................................6
Floral Characteristics ...........................................................................................................................6
IVC Ecological Systems in the LRGV ......................................................................................14
Tamaulipan Floodplain .....................................................................................................14
Tamaulipan Mixed Deciduous Thornscrub ...................................................................15
Texas Coastal Salt and Brackish Tidal Marsh ..............................................................15
Tamaulipan Closed Depression Wetland ......................................................................15
Tamaulipan Calcareous Thornscrub ..............................................................................17
Tamaulipan Ramadero .....................................................................................................17
Tamaulipan Savanna Grassland .....................................................................................17
Texas Coast Dune and Coastal Grassland ....................................................................17
Tamaulipan Loma Shrubland and Grassland ................................................................18
Texas Saline Coastal Prairies .........................................................................................18
Tamaulipan Palm Grove Riparian Forest .......................................................................18
Tamaulipan Saline Lake ...................................................................................................18
Seagrass Meadows of Laguna Madre ...................................................................................19
Restoration of Threatened Plant Communities .....................................................................20
Threatened and Endangered Plants ......................................................................................22
Overview.............................................................................................................................22
Ashy Dogweed ..................................................................................................................25
South Texas Ambrosia .....................................................................................................25
Star Cactus ........................................................................................................................27
Tamaulipan Kidneypetal ...................................................................................................27
Walker’s Manioc ...............................................................................................................27
Zapata Bladderpod ...........................................................................................................27
Faunal Characteristics .......................................................................................................................28
Invertebrates ..............................................................................................................................28
Amphibians and Reptiles ..........................................................................................................34
Fishes ...........................................................................................................................................35
Birds .............................................................................................................................................36
Northern Aplomado Falcon .............................................................................................36
Orioles .................................................................................................................................38
Other Riparian Dependents .............................................................................................38
Doves and Pigeons ...........................................................................................................40
Thornscrub Species .........................................................................................................40
Waterfowl, Colonial Waterbirds, and Shorebirds/Seabirds ......................................40
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Unique Aspects of the Lower Rio Grande Valley—Continued
Faunal Characteristics—Continued
Mammals .....................................................................................................................................42
Bats .....................................................................................................................................42
Small Mammals .................................................................................................................42
Northern Ocelot in the LRGV ...........................................................................................43
Ongoing Challenges Facing the LRGV ......................................................................................................46
Human Population Growth and Associated Challenges ..............................................................46
Urbanization, Industrialization, and Economic Development ............................................47
Energy Development .................................................................................................................49
Oil and Gas .........................................................................................................................49
Wind Power .......................................................................................................................49
Pollution and Waste Management .........................................................................................51
Human Health and Associated Benefits of Land Conservation .........................................51
Agriculture ...........................................................................................................................................52
Changes in Crop Production ....................................................................................................52
Pesticides, Herbicides, and Associated Contamination .....................................................53
Continued Agricultural Pressure on Native Habitats and Water Resources ..................55
Flood Control and Water Development ...........................................................................................56
Flood-control Activities .............................................................................................................56
Irrigation and Water Rights ......................................................................................................56
Detrimental Effects of Water Development on LRGV Biota ................................................58
Exotic and Invasive Species .............................................................................................................60
Plants ...........................................................................................................................................60
Water Hyacinth .................................................................................................................60
Hydrilla ................................................................................................................................60
Giant Reed ..........................................................................................................................60
Buffelgrass .........................................................................................................................62
Guineagrass .......................................................................................................................62
Saltcedar ............................................................................................................................62
Animals ........................................................................................................................................62
Red Imported Fire Ant ......................................................................................................62
Africanized Honey Bee ....................................................................................................62
Exotic or Naturalized Birds .............................................................................................63
Exotic Mammals ................................................................................................................63
Climate Change ...................................................................................................................................63
Border Issues and Homeland Security ...........................................................................................64
Conservation Opportunities for the LRGV in the 21st Century ..............................................................67
Productive Partnerships ....................................................................................................................67
Ecotourism and Conservation Activities ................................................................................67
Agency and Nongovernmental Organization Cooperation .................................................68
Cooperation with Mexico .........................................................................................................71
Conservation and Land Acquisition .................................................................................................72
Future Management Directions and Needs ............................................................................................73
Wildlife Corridors ................................................................................................................................78
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Conclusion.....................................................................................................................................................79
References ....................................................................................................................................................80
Appendixes A–C
A. Research conducted on seagrass of the Lower and Upper Laguna
Madre since the early 1990s ...................................................................................................115
B. Peer-reviewed publications focused on the Lower Rio Grande Valley
on 58 bird species since the late 1980s .................................................................................116
C. Peer-reviewed publications focused on the Lower Rio Grande Valley
on northern ocelots by subject categories since the late 1980s ......................................119
Figures
1. Map showing the South Texas Refuge Complex, including properties
in the Lower Rio Grande Valley National Wildlife Refuge (NWR),
Santa Ana NWR, and Laguna Atascosa NWR in Starr, Hidalgo,
Willacy, and Cameron Counties in southern Texas .................................................................3
2. Map showing the six major physiographic zones in the Lower
Rio Grande Valley ..........................................................................................................................8
3. Photographs showing vegetative diversity of inland ecological systems
in the Lower Rio Grande Valley along the Rio Grande and upslope from it.
A, Tamaulipan Floodplain. B, Tamaulipan Mixed Deciduous Thornscrub
upslope from the Rio Grande. C, Tamaulipan Calcareous Thornscrub ..............................14
4. Photographs showing coastal ecological systems illustrating the rich
landscape and floral diversity of the coastal areas in the Lower
Rio Grande Valley. A, Tamaulipan Ramadero associated with Tamaulipan
Floodplain. B, Tamaulipan Loma Shrubland and Grassland.
C, Tamaulipan Palm Grove Riparian Forest. D, Texas Coast Dune
and Coastal Grassland. E, Texas Coastal and Brackish Tidal Marsh.
F, Texas Coast Dunes and Coastal Grasslands. G, Tamaulipan Loma
Shrubland and Grassland ..........................................................................................................16
5. Photographs showing shallow-water seagrass meadows, a dominant
feature of the Lower Laguna Madre offshore of the Lower Rio Grande Valley ...............19
6. Graphs showing restoration activities conducted by the
U.S. Fish and Wildlife Service in the Lower Rio Grande Valley
National Wildlife Refuge from 1995 through 2012. A, cumulative number
of plants. B, acres planted. C, plants per acre and acres planted. ....................................21
7. Photographs showing restoration of old cropland to native forest
and brushland, a high conservation priority in the Lower Rio Grande
Valley National Wildlife Refuge. Restoration sequence of the Sam Fordyce
tract: A, preplanting in October 2007; B, seedling planting by hand in
October 2007; C, direct seeding of grasses and herbaceous plants with
a tractor; D, restoration progress by July 2008; and E, restoration success
by March 2015 .............................................................................................................................23
8. Photographs showing endangered plants of the Lower Rio Grande Valley.
A, Ayenia limitaris (Tamaulipan kidneypetal). B, Ambrosia cheiranthifolia
(South Texas ambrosia). C, Astrophytum asterias (star cactus). D, Physaria
thamnophila (Zapata bladderpod). E, Manihot walkerae (Walker’s manioc) ...................26
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9. Photographs showing diversity of butterflies in the Lower Rio Grande Valley,
which is unparalleled with nearly 300 confirmed species, of which 163 are
generally not found elsewhere in the United States. Striking representatives
are A, Heliconius charithonia (zebra heliconian); B, Agraulis vanillae
(Gulf fritillary); C, Chlosyne janais (crimson patch); D, Papilio polyxenes
(black swallowtail butterfly); E, Lasaia sula (blue metalmark); and
F, Diaethria anna (Anna’s eighty-eight) ...................................................................................33
10. Photograph showing an endangered Lepidochelys kempii (Kemp’s ridley
nesting on South Padre Island ................................................................................................35
11. Photographs showing the endangered Falco femoralis septentrionalis
(northern aplomado falcon) ......................................................................................................37
12. Photographs showing prominent species of birds found in the Lower Rio Grande
Valley (LRGV). With more than 420 species of birds documented
in the LRGV, riparian forest and brushland species have high conservation
value. A, the iconic Icterus gularis (Altamira oriole); B, I. graduacauda
(Audubon’s oriole); C, Amazilia yucatanensis (buff-bellied hummingbird);
D, Ortalis vetula (plain chachalaca); and E, Cyanocorax yncas (green jay) .....................39
13. Photographs showing wetland birds and doves, which are notably
diverse and abundant in the Lower Rio Grande Valley. A, Zenaida
asiatica (white-winged dove), an important game species; B, the
growingly rare Leptotila verreauxi (white-tipped dove) and
C, Patagioenas flavirostris (red-billed pigeon); D, Dendrocygna
autumnalis (black-bellied whistling ducks); and E, wintering Aythya
americana (redheads) ................................................................................................................41
14. Photographs showing the endangered Leopardus pardalis
albescens (northern ocelot). Perhaps more than any other species,
the northern ocelot is emblematic of the substantial conservation
challenges facing the biota of the Lower Rio Grande Valley ..............................................44
15. Graph showing nearly exponential growth of the human population
in the Lower Rio Grande Valley from 1940 to 2013, projected to reach
about 3 million people by 2050 ..................................................................................................46
16. Map showing urbanized areas in the Lower Rio Grande Valley, which
form an almost continuous band from Roma, Texas, to beyond
Brownsville, Tex ..........................................................................................................................48
17. Photographs showing wind-power development in the Lower Rio
Grande Valley, which has grown from zero in the late 1980s to about
1,400 wind turbine towers operated by 15 companies and often juxtaposed
near or in important brushlands and coastal habitats .........................................................50
18. Photographs showing some of the many outdoor open-space recreational
and educational opportunities available in the Lower Rio Grande Valley ........................52
19. Map showing the three major dams, water-control canals, and the
Arroyo Colorado in the Lower Rio Grande Valley (LRGV) that negatively
affect remnant flood-plain forests and restoration efforts along the LRGV
by altering, and even eliminating, natural flow and flooding regimes ...............................57
20. Photographs showing invasive and (or) nonnative plant and animal
species that challenge conservation efforts in the Lower Rio Grande
Valley: A, Arundo donax (giant reed); B, Cenchrus ciliaris (buffelgrass);
C, Tamarix aphylla (athel tamarisk); D, Aratinga holochlora (green parakeet);
and E, Amazona viridigenalis (red-crowned amazon) ..........................................................61