Riparian bird community from the Rio Sabinas, Coahuila, Mexico.
Resumen.-Las zonas riberenas han sido identificadas como habitats clave para la vida silvestre, especialmente para el paisaje arido de Norteamerica; sin embargo en el norte de Mexico dichas zonas han sido poco estudiadas. El presente estudio se llevo a cabo en el habitat ribereno dominado por sabinos (Taxodium mucronatum) del Rio Sabinas, Coahuila, Mexico, de diciembre de 2004 a noviembre de 2005. Se llevaron a cabo muestreos mensuales utilizando un total de 443 puntos de conteo de radio fijo en tres zonas del rio caracterizadas por distintos niveles de disturbio, de menor a mayor: Melchor Muzquiz, San Juan de Sabinas y Sabinas. Se registraron un total de 168 especies. La zona Melchor Muzquiz mostro el menor numero de especies corregidas por rarefacction y un numero significativamente menor de especies e individuos por punto de conteo. Los diagramas Olmstead-Tukey por zona tambien mostraron diferencias en la dominancia de las especies. Se registraron especies importantes desde el punto de vista de la conservation, como Mycteria americana y Passerina ciris.
The importance of riparian zones for breeding and migrant birds has been extensively documented (e. g., Knopf et al. 1988; Knopf & Samson 1994; Skagen et al. 1998; Anthony et al. 1996; Finch & Yong 2000; Flannery et al. 2004; Kelly & Hutto 2005; Villasenor 2006). While riparian woodlands of North America constitute less than 1% of the area of arid landscapes they support more reproductive birds than the extensive surroundings (e.g., Knopf et al. 1988). Unfortunately, it has been suggested that at least 95% of all western riparian habitats have been altered in some way during the past century (Ohmart 1994), and that such destruction may be the most important factor in the decline of some western North American landbird species during the past century (DeSante & George 1994). However, the effects of such alterations on riparian systems may be unnoticed for decades due to longevity of cottonwoods (Rood & Mahoney 1993) and other riparian trees such as Montezuma bald cypresses. This could cause a delay in awareness of the need for conservation, management, and restoration actions.
In northwestern Mexico, there have been few studies conducted on the importance of riparian habitats for migratory birds (Hutto 1995; Villasenor 2006), but none in the northeastern portion. The Rio Sabinas (130 km length) is located in northeastern Coahuila, running from the Sierra Santa Rosa near Melchor Muzquiz to the Venustiano Carranza Dam near Juarez municipality (Fig. 1). Its avifauna has been little studied even though it is a Priority Terrestrial Region for Conservation in Mexico (RTP-152, Arriaga et al. 2000), a State Natural Protected Area (Periodico Oficial 1998), and an important biological corridor linking northern Mexico with the southern United States through the well-conserved Sierra Santa Rosa, Maderas del Carmen and Big Bend National Park. This connection is also maintained downstream from the Venustiano Carranza Dam where the river is named the Rio Salado; it flows through Nuevo Leon and Tamaulipas and enters the Falcon Reservoir which is part of the Rio Grande. Its riparian vegetation is dominated by Montezuma bald cypress (Taxodium mucronatum, locally known as "sabino"), while pecan (Carya illinoinensis), sycamore (Platanus occidentalis), sugar hackberry (Celtis laevigata), and Mexican ash (Fraxinus berlanderiana) are also present. Its shrub stratum is variable but includes spiny hackberry (C. pallida), huisache (Acacia farnesiana), catclaw (A. greggii), blackbrush (A. rigidula), honey mesquite (Prosopis glandulosa), Texas persimmon (Dyospiros texana), and Mexican mulberry (Morus celtidifolia). The herbaceous cover is composed principally of straggler daisy (Calyptocarpus vialis).
[FIGURE 1 OMITTED]
This area faces serious conservation issues such as lack of biological knowledge, overgrazing, deforestation, and open-ceiling coal mining. The latter is especially harmful because it drastically modifies the environment and frequently breaks into the freatic mantle and extracts water (sometimes from very near the river: Trevino-Garza et al. 2002), affecting the hydrologic dynamics of the basin and interrupting the water flow in some sections of the river. Three distinct sections are observed in the riparian habitat qualitatively characterized by different levels of disturbance. The Melchor Muzquiz (MM) municipality section has a well preserved riparian habitat with mature and young woodland patches; the San Juan de Sabinas (SJS) municipality section contains partially preserved habitat, with mature patches but several rural and urban localities; and the Sabinas (S) municipality section has deteriorated and fragmented riparian woodland vegetation in a narrow corridor which includes dead bald cypresses (due to coal mining activities). Therefore, the objectives of this study were to characterize the bird community of the Rio Sabinas and compare communities among sections with different levels of disturbance.
A systematic sampling of birds was conducted from December 2004 to November 2005 along the Rio Sabinas, in localities where Montezuma bald cypresses were present near the municipalities of Melchor Muzquiz (MM), San Juan de Sabinas (SJS) and Sabinas (S). Sections were visited monthly on a rotating basis to obtain a balanced sampling design. A total of 443 point counts (10 min, 25 m radius: Ralph et al. 1996) in 247 randomly selected sites were sampled, covering an area of 34.5 ha and 64 km of river length (approximately 50% of the total). Point counts were conducted by a single observer to reduce bias in detectability. The area was visited from December 2005 to January 2006 and May to August 2006, adding new records to the check-list. Species, including common and scientific names, were listed in phylogenetic order (Tables 1 & 2) following the AOU checklist (1998; 2000) and its supplements (Banks et al. 2002-2007). The residency status of each species was determined on the basis of field observations and information provided by Howell & Webb (1995). Only results from the one-year systematic effort were used for the analysis described below.
Table 1. List of breeding species in phylogenetic order (AOU 1998, 2000; Banks et al. 2002-2007); their residency status (R): PR=Permanent Resident; SR=Summer Resident; WR=Winter Resident. Density (D, birds/hectare) is shown per species. Olmstead Tukey Dominance for breeding (OT-B) and wintering (OT-W) seasons: C=Common; U= Uncommon; R=Rare. Olmstead-Tukey Dominance (OT) per section: MM= Melchor Muzquiz; SJS= San Juan de Sabinas; S= Sabinas; FO=Frequency of occurrence; A= Abundance. Species in bold were used for quantitative analysis. Scientific Common Name R D OT-B OT-W Name Breeding Species Dendrocygna Mack-bellied SR 2.59 C auntmnalis + Whistling-Duck Cairina Muscovy Duck PR 0.07 R R moschala *+ Anas Mallard PR/WR 0.41 R U platyrhynchos Meleagris Wild Turkey PR 0.11 R - gallopavo * Colinus Northern Bobwhite PR 0.16 R R virginianus Tachybaptus Least Grebe PR 0.02 - R dominicus * Podilymbus Pied-billed Grebe PR podiceps Phalacrocorax Nootropic Cormorant SR 0.84 U brasilianus Ardea herodias + Great Blue Heron PR 0.09 - R Ardea alba + Great Egret PR 0.16 R R Egretta Inula Snowy Egret SR 0.15 R Bubulcus ibis Cattle Egret PR 0.02 R - Butorides Green Heron SR 0.38 R virescens Nyctanassa Yellow-crowned SR 0.72 U violncea + Night-Heron Coragyps Black Vulture PR 0.66 U U atratus Cathartes Turkey Vulture PR 1.31 C U aura Elanus White-tailed Kite SR 0.15 R leucurus + Buteogallus Common Black-Hawk SR anthracinus *#+ Parabuteo Harris's Hawk PR 0.11 - R unicinctus * Buteo lineatus + Red-shouldered Hawk PR/WR 0.36 R U Butea nitidus #+ Gray Hawk PR 0.18 R U Buteo Swainson's Hawk SR 0.04 R swainsoni * Buteo Red-tailed Hawk PR jamaicensis Charadrius Killdeer PR 0.14 R R vociferus Zenaida Mourning Dove PR 1.44 C C macroura Columbian Inca Dove SR 0.31 R inca Columbina Common Ground-Dove PR 0.04 U R passerina Leptotila White-tipped Dove PR? 0.02 R verreauxi Coccyzus Yellow-billed Cuckoo SR 0.11 R americanus Geococcyx Greater Roadrunner PR 0.02 R - californianus Crolophaga Groove-billed Ani SR 0.08 R sulcirostris Tyta alba Barn Owl PR 0.04 R - Megascops Western Screech-Owl PR 0.04 - R kennicottii Megascops Eastern Screech-Owl PR asio Bubo Great Horned Owl PR 0.02 R virgnianus Glaucicdium Northern Pygmy-Owl SR gnome Chordeiles Lesser Nighthawk SR 0.04 R acutipennis Latnpornis Blue-throated SR 0.04 R clemenciae Hummingbird Colo thorax Lucifer Hummingbird SR lucifer Archllochus Black-chinned SR 0.88 C alexandri Hummingbird Selasphorus Broad-tailed SR platycercus Hummingbird Meguceryle Ringed Kingfisher PR 0.65 torquata + Chloroceryle Green Kingfisher PR 1.19 C C americana Melunerpes Golden-fronted PR 5.19 C C aurifrons Woodpecker Picaides Ladder-backed PR 1.71 C C scalaris Woodpecker Camptostoma Northern SR? imberbe #+ Beardless-Tyrannulet Sayornis Black Phoebe PR 2.34 C C nigricans Pyocephalus Vermilion Flycatcher PR 0.38 U U rubinus Myiarchus Ash-throated SR 0.91 U cinerascens Flycatcher Myiarchus Brown-crested SR 2.82 C tyrannulus Flycatcher Pitangus Great Kiskadee PR 1.81 C C sulphuratus Tyrannus Couch's Kingbird SR 1.10 C couchii + Tyrannus Cassin's Kingbird SR 0.19 R vociferans Vireo griseus White-eyed Vireo PR 1.17 C C Vireo bellii Bell's Vireo SR 0.69 U Cyanocorax Green Jay PR 0.29 - R yncas + Corvus sp. Raven 0.70 U R Corvus Chihuahuan Raven PR cryptoleuais Corvus corax Common Raven PR Hirundo Barn Swallow SR rustica Baelophus Black-crested PR 4.60 C C atricristatus Titmouse Auriparus Verdin PR 0.18 R R flaviceps Thryothorus Carolina Wren PR 5.28 C C ludovicianus Thryomanes Bewick's Wren PR 0.63 U U bewickii Polioptila Blue-gray PR 0.72 R C caerulea Gnatcatcher Mimas Nothern Mockingbird PR 0.31 R R polyglottos Toxosloma Long-billed Thrasher PR 0.22 R R longirostre Toxostoma Curve-bil1ed PR curvirostre Thrasher Geothtypis Common Yellowthroat PR 0.11 R R trichas Myioborus Painted Redstart SR pictus Basileuterus Rufous-capped PR 0.05 - R rufifrons + Warbler Icteria Yellow-breasted Chat SR 3.16 C virens Piranga flava Hepatic Tanager PR? R R Piranga rubra Summer Tanager SR 6.36 C Arremonops Olive Sparrow PR 1.53 C U rufivirgatus Chondestes Lark Sparrow PR 0.57 - R grammacus Amphispiza Black-throated PR R R bilineata Sparrow Cardinalis Northern Cardinal PR 4.37 C C cardinalis Cardinalis Pyrrhuloxia PR 0.09 - U sinuatus Passerina Blue Grosbeak SR 0.49 U caerulea Passerina Painted Bunting SR 1.33 C ciris Agelaim Red-winged Blackbird PR 0.41 phoeniceus Quiscalus Great-tailed Crackle PR 0.66 R R mexicanus Mololhnis Bronzed Cowbird PR aeneus Molothnts Brown-headed Cowbird PR 0.11 R - ater Icterus Orchard Oriole SR 0.27 R spurius Icterus Hooded Oriole SR 0.08 R cucullatus Icterus Bullock's Oriole SR 0.11 R bullockii Icterus Audubon's Oriole PR 0.02 - R graduacauda Carpodacus House Finch PR 0.22 R R mexicanus Cardueils Lesser Goldfinch PR 1.92 C C psaltria Scientific Common Name MM Name FO A (ln + 1) OT Dendrocygna Black-bellied 1 2(1.7) R autumnalis + Whistling-Duck Cairina moschata Muscovy Duck *+ Anas Mallard platyrhynchos Meleagris Wild Turkey 1 4(2.4) R gallopavo * Colinus Northern Bobwhite virginianus Tachybaptus Least Grebe dominicus * Podilymbus Pied-billed Grebe podiceps Phalacrocorax Neotropic Cormorant brasilianus Ardea herodias + Great Blue Heron Ardea alba + Great Egret Egretta thula Snowy Egret Bubulcus ibis Cattle Egret Butorides Green Heron 1 2(1.7) R virescens Nyctanassa Yellow-crowned 8(3.1) U 9.1 violacea + Night-Heron Coragyps atratus Black Vulture 4 12(3.5) R Cathartes aura Turkey Vulture 9 11(3.4) U Elanus leucurus + White-tailed Kite Buteogallus Common Black-Hawk anthracinus *#- Parabuteo Harris's Hawk unicinctus * Buteo linealus + Red-shouldered Hawk 1 1(1) R Buteo nitidus #- Gray Hawk 1 1(1) R Buteo swainsoni * Swainson's Hawk Buteo jamaicensis Red-tailed Hawk Charadrius Killdeer vociferus Zenaida macroura Mourning Dove 16 20(4) C Columbina inca Inca Dove Columbina Common Ground-Dove 1 1(1) R passerina Leptotila White-tipped Dove verreauxi Coccyzus Yellow-billed Cuckoo 1 2(1.7) R americanus Geococcyx Greater Roadrunner californianus Crotophaga Groove-billed Ani sulcirostris Tyto alba Barn Owl Megascops Western Screech-Owl kennicottii Megascops asio Eastern Screech-Owl Bubo virgnianus Great Horned Owl Glaucidium gnoma Northern Pygmy-Owl Chordeiles Lesser Nighthawk acutipennis Lampornis Blue-throated Hummingbird 1 1(1) R clemenciae Calothorax Lucifer Hummingbird lucifer Archilochus Black-chinned Hummingbird 7 7(2.9) R alexandri Selasphorus Broad-tailed Hummingbird platycercus Megaceryle Ringed Kingfisher 5 5(2.6) R torquata + Chloroceryle Green Kingfisher 14 14(3.6) C americana Melanerpes Golden-fronted Woodpecker 30 39(4.7) C aurifrons Picoides scalaris Ladder-backed Woodpecker 18 20(4) C Camptostoma Northern imberbe #- Beardless-Tyrannulet Sayornis Black Phoebe 11 11(3.4) U nigricans Pyrocephalus Vermilion Flycatcher 7 10(3.3) U rubinus Myiarchus Ash-throated Flycatcher 8 11(3.4) U cinerascens Myiarchus Brown-crested Flycatcher 31 44(4.8) C tyrannulus Pitangus Great Kiskadee 19 26(4.3) C sulphuratus Tyrannus couchii Couch's Kingbird 13 14(3.6) C + Tyrannus Cassin's Kingbird vociferans Vireo griseus White-eyed Vireo 11 14(3.6) U Vireo bellii Bell's Vireo 3 4(2.4) R Cyanocorax yncas Green Jay + Corvus sp. Raven 8 15(3.7) U Corvus Chihuahuan Raven cryptoleucus Corvus corax Common Raven Hirundo rustica Barn Swallow Baelopnus Black-crested Titmouse 28 37(4.6) C atricristatus Auriparus Verdin flaviceps Thryothorus Carolina Wren 68 102(5.6) C ludovicianus Thryomanes Bewick's Wren 2 3(2.1) R bewickii Polioptila Blue-gray Gnatcatcher 1 1(1) R caerulea Mimus polyglottos Nothern Mockingbird Toxostoma Long-billed Thrasher 2 3(2.1) R longirostre Toxostoma Curve-billed Thrasher curvirostre Geothlypis Common Yellowthroat 3 3(2.1) R trichas Myioborus pictus Painted Redstart Basileuterus Rufous-capped Warbler rufifrons + Icteria virens Yellow-breasted Chat 13 13(3.6) C Piranga flava Hepatic Tanager Piranga rubra Summer Tanager 50 98(5.6) C Arremonops Olive Sparrow 24 27(4.3) C rufivirgatus Chondestes Lark Sparrow grammacus Amphispiza Black-throated Sparrow bilineata Cardinalis Northern Cardinal 21 33(4.5) C cardinalis Cardinalis Pyrrhuloxia sinuatus Passerina Blue Grosbeak 6 7(2.9) R caerulea Passerina ciris Painted Bunting 14 20(4) C Agelaius Red-winged Blackbird 2 2(1.7) R phoeniceus Quiscalus Great-tailed Grackle mexicanus Mololhrus aeneus Bronzed Cowbird Molothrus ater Brown-headed Cowbird Icterus spurius Orchard Oriole 4 5(2.6) R Icterus Hooded Oriole cucullatus Icterus bullockii Bullock's Oriole Icterus Audubon's Oriole graduacauda Carpodacus House Finch 1 1(1) R mexicanus Carduelis Lesser Goldfinch 19 39(4.7) C psaltria Scientific Common Name SJS Name FO A (ln + 1) OT Dendrocygna Black-bellied 21.6 78(5.4) C autumnalis + Whistling-Duck Cairina moschata *+ Muscovy Duck 1.1 1(1) R Anas platyrhynchos Mallard 3.4 5(2.6) R Meleagris gallopavo Wild Turkey * Colinus virginianus Northern Bobwhite Tachybaptus Least Grebe dominicus * Podilymbus podiceps Pied-billed Grebe Phalacrocorax Neotropic Cormorant 3.4 4(2.4) R brasilianus Ardea herodias + Great Blue Heron Ardea alba + Great Egret 1.1 2(1.7) R Egretta thula Snowy Egret Bubulcus ibis Cattle Egret Butorides virescens Green Heron 4.5 5(2.6) R Nyctanassa violacea Yellow-crowned 9(3.2) U 1.4 + Night-Heron Coragyps atratus Black Vulture 3.4 4(2.4) R Cathartes aura Turkey Vulture 5.7 7(3) U Elanus leucurus + White-tailed Kite 2.3 3(2.1) R Buteogallus Common Black-Hawk anthracinus *#- Parabuteo unicinctus Harris's Hawk 1.1 1(1) R * Buteo linealus + Red-shouldered Hawk 3.4 4(2.4) R Buteo nitidus #- Gray Hawk 2.3 3(2.1) R Buteo swainsoni * Swainson's Hawk 1.1 1(1) R Buteo jamaicensis Red-tailed Hawk Charadrius Killdeer vociferus Zenaida macroura Mourning Dove 25.0 31(4.4) C Columbina inca Inca Dove 1.1 1(1) R Columbina passerina Common Ground-Dove 3.4 5(2.6) R Leptotila verreauxi White-tipped Dove Coccyzus americanus Yellow-billed Cuckoo 3.4 3(2.1) R Geococcyx Greater Roadrunner californianus Crotophaga Groove-billed Ani sulcirostris Tyto alba Barn Owl 1.1 2(1.7) R Megascops Western Screech-Owl kennicottii Megascops asio Eastern Screech-Owl Bubo virgnianus Great Horned Owl 1.1 1(1) R Glaucidium gnoma Northern Pygmy-Owl Chordeiles Lesser Nighthawk acutipennis Lampornis Blue-throated Hummingbird clemenciae Calothorax lucifer Lucifer Hummingbird Archilochus Black-chinned Hummingbird 6.8 6(2.8) R alexandri Selasphorus Broad-tailed Hummingbird platycercus Megaceryle torquata Ringed Kingfisher 4.5 6(2.8) R + Chloroceryle Green Kingfisher 17.0 16(3.8) C americana Melanerpes Golden-fronted Woodpecker 52.3 75(5.3) C aurifrons Picoides scalaris Ladder-backed Woodpecker 13.6 14(3.6) C Camptostoma imberbe Northern #- Beardless-Tyrannulet Sayornis nigricans Black Phoebe 35.2 40(4.7) C Pyrocephalus Vermilion Flycatcher 1.1 1(1) R rubinus Myiarchus Ash-throated Flycatcher 3.4 5(2.6) R cinerascens Myiarchus Brown-crested Flycatcher 13.6 14(3.6) C tyrannulus Pitangus Great Kiskadee 13.6 15(3.7) C sulphuratus Tyrannus couchii + Couch's Kingbird 3.4 3(2.1) R Tyrannus vociferans Cassin's Kingbird Vireo griseus White-eyed Vireo Vireo bellii Bell's Vireo 6.8 7(3) U Cyanocorax yncas + Green Jay 3.4 3(2.1) R Corvus sp. Raven 3.4 3(2.1) R Corvus cryptoleucus Chihuahuan Raven Corvus corax Common Raven Hirundo rustica Barn Swallow Baelopnus Black-crested Titmouse 36.4 69(5.2) C atricristatus Auriparus flaviceps Verdin Thryothorus Carolina Wren 53.4 74(5.3) C ludovicianus Thryomanes bewickii Bewick's Wren 4.5 4(2.4) R Polioptila caerulea Blue-gray Gnatcatcher Mimus polyglottos Nothern Mockingbird Toxostoma Long-billed Thrasher 2.3 2(1.7) R longirostre Toxostoma Curve-billed Thrasher curvirostre Geothlypis trichas Common Yellowthroat Myioborus pictus Painted Redstart Basileuterus Rufous-capped Warbler rufifrons + Icteria virens Yellow-breasted Chat 26.1 36(4.6) C Piranga flava Hepatic Tanager Piranga rubra Summer Tanager 43.2 58(5.1) C Arremonops Olive Sparrow 36.4 44(4.8) C rufivirgatus Chondestes Lark Sparrow grammacus Amphispiza Black-throated Sparrow bilineata Cardinalis Northern Cardinal 34.1 53(5) C cardinalis Cardinalis sinuatus Pyrrhuloxia Passerina caerulea Blue Grosbeak 3.4 5(2.6) R Passerina ciris Painted Bunting 8.0 7(3) U Agelaius phoeniceus Red-winged Blackbird Quiscalus mexicanus Great-tailed Grackle 1.1 5(2.6) R Mololhrus aeneus Bronzed Cowbird Molothrus ater Brown-headed Cowbird 1.1 4(2.4) R Icterus spurius Orchard Oriole Icterus cucullatus Hooded Oriole 3.4 3(2.1) R Icterus bullockii Bullock's Oriole Icterus graduacauda Audubon's Oriole Carpodacus House Finch mexicanus Carduelis psaltria Lesser Goldfinch 36.4 57(5) C Scientific Common Name S Name FO A (ln + 1) OT Dendrocygna Black-bellied 13.5 22(4.1) C autumnalis + Whistling-Duck Cairina moschata *+ Muscovy Duck 1.4 1(1) R Anas platyrhynchos Mallard 5.4 6(2.8) R Meleagris gallopavo Wild Turkey 1.4 2(1.7) R * Colinus virginianus Northern Bobwhite 1.4 2(1.7) R Tachybaptus Least Grebe dominicus * Podilymbus podiceps Pied-billed Grebe Phalacrocorax Neotropic Cormorant 12.2 18(3.9) U brasilianus Ardea herodias + Great Blue Heron Ardea alba + Great Egret 5.4 5(2.6) R Egretta thula Snowy Egret 2.7 4(2.4) R Bubulcus ibis Cattle Egret 1,1 1(1) R Butorides virescens Green Heron 5.4 4(2.4) R Nyctanassa violacea Yellow-crowned 2(1.7) R + Night-Heron Coragyps atratus Black Vulture Cathartes aura Turkey Vulture 16.2 16(3.8) C Elanus leucurus + White-tailed Kite 1.4 1(1) R Buteogallus Common Black-Hawk anthracinus *#- Parabuteo unicinctus Harris's Hawk * Buteo linealus + Red-shouldered Hawk 4.1 4(2.4) R Buteo nitidus #- Gray Hawk Buteo swainsoni * Swainson's Hawk 1.4 1(1) R Buteo jamaicensis Red-tailed Hawk Charadrius Killdeer 4.1 5(2.6) R vociferus Zenaida macroura Mourning Dove 21.6 24(4.2) C Columbina inca Inca Dove Columbina passerina Common Ground-Dove 6.8 9(3.2) U Leptotila verreauxi White-tipped Dove 1.4 1(1) R Coccyzus americanus Yellow-billed Cuckoo Geococcyx Greater Roadrunner 1.4 1(1) R californianus Crotophaga Groove-billed Ani 2.7 2(1.7) R sulcirostris Tyto alba Barn Owl Megascops Western Screech-Owl kennicottii Megascops asio Eastern Screech-Owl Bubo virgnianus Great Horned Owl Glaucidium gnoma Northern Pygmy-Owl Chordeiles Lesser Nighthawk 1.4 1(1) R acutipennis Lampornis Blue-throated Hummingbird clemenciae Calothorax lucifer Lucifer Hummingbird Archilochus Black-chinned Hummingbird 12.2 10(3.3) U alexandri Selasphorus Broad-tailed Hummingbird platycercus Megaceryle torquata Ringed Kingfisher 12.2 9(3.2) U + Chloroceryle Green Kingfisher 14.9 12(3.5) C americana Melanerpes Golden-fronted Woodpecker 82.4 102(5.6) C aurifrons Picoides scalaris Ladder-backed Woodpecker 21.6 19(4) C Camptostoma imberbe Northern #- Beardless-Tyrannulet Sayornis nigricans Black Phoebe 18.9 19(4) C Pyrocephalus Vermilion Flycatcher 2.7 4(2.4) R rubinus Myiarchus Ash-throated Flycatcher 8.1 8(3.1) U cinerascens Myiarchus Brown-crested Flycatcher 17.6 18(3.9) C tyrannulus Pitangus Great Kiskadee 13.5 12(3.5) C sulphuratus Tyrannus couchii + Couch's Kingbird 9.5 11(3.4) U Tyrannus vociferans Cassin's Kingbird 4.1 5(2.6) R Vireo griseus White-eyed Vireo 24.3 22(4.1) C Vireo bellii Bell's Vireo 10.8 8(3.1) U Cyanocorax yncas + Green Jay Corvus sp. Raven 12.2 19(4) U Corvus cryptoleucus Chihuahuan Raven Corvus corax Common Raven Hirundo rustica Barn Swallow Baelopnus Black-crested Titmouse 27.0 26(4.3) C atricristatus Auriparus flaviceps Verdin 4.1 6(2.8) R Thryothorus Carolina Wren 55.4 48(4.9) C ludovicianus Thryomanes bewickii Bewick's Wren 18.9 18(3.9) C Polioptila caerulea Blue-gray Gnatcatcher Mimus polyglottos Nothern Mockingbird Toxostoma Long-billed Thrasher 4.1 4(2.4) R longirostre Toxostoma Curve-billed Thrasher curvirostre Geothlypis trichas Common Yellowthroat Myioborus pictus Painted Redstart Basileuterus Rufous-capped Warbler rufifrons + Icteria virens Yellow-breasted Chat 35.1 34(4.5) C Piranga flava Hepatic Tanager Piranga rubra Summer Tanager 31.1 37(4.6) C Arremonops Olive Sparrow 32.4 28(4.3) C rufivirgatus Chondestes Lark Sparrow grammacus Amphispiza Black-throated Sparrow bilineata Cardinalis Northern Cardinal 50.0 50(4.9) C cardinalis Cardinalis sinuatus Pyrrhuloxia Passerina caerulea Blue Grosbeak 5.4 5(2.6) R Passerina ciris Painted Bunting 8.1 7(3) U Agelaius phoeniceus Red-winged Blackbird 12.2 19(4) U Quiscalus mexicanus Great-tailed Grackle 1.4 4(2.4) R Mololhrus aeneus Bronzed Cowbird Molothrus ater Brown-headed Cowbird 1.4 2(1.7) R Icterus spurius Orchard Oriole 2.7 2(1.7) R Icterus cucullatus Hooded Oriole Icterus bullockii Bullock's Oriole 4.1 3(2.1) R Icterus graduacauda Audubon's Oriole Carpodacus House Finch 5.4 7(3) U mexicanus Carduelis psaltria Lesser Goldfinch 9.5 9(3.2) U * Species under Mexican law protection (NOM-059-SEMARNAT-2001, DOF 2002); # Species Listed as threatened for Texas (TPWD 2003); + New records for Coahuila (Ruvalcaba-Ortega & Gonzalez-Rojas 2009). Table 2. List of non-breeding species in phylogenetic order (AOU 1998, 2000; Banks et al. 2002-2007); their residency status (R): WR=Winter Resident; T=Transient; and O=Occasional. Density (D, birds/hectare) is shown per species. Olmstead Tukey Dominance for wintering season (OT- W): C=Common; U= Uncommon; R=Rare. Species in bold were used for quantitative analysis. R D OT-W Non-breeding Species Scientific Name Common Name Aix sponsa Wood Duck WR/PR? 0.45 U Anas strepera Gadwall WR 0.14 R Anas discors Blue-winged Teal T 0.24 U Anas cyanoptera Cinnamon Teal T Anas crecca Green-winged Teal T Phalacrovorax auritus Double-crested T Cormorant Egretta tricolor Tricolored Heron O 0.02 R Nycticorax nycticorax Black-crowned Night-Heron WR 0.10 R Plegudix chihi # White-faced Ibis T Myaeria americana *#+ Wood Stork O Circus cyaneus Northern Harrier O Accipiter striatus * Sharp-shinned Hawk WR 0.07 R Accipiter cooperii * Cooper's Hawk WR 0.07 R Buteo albicattdatus *# White-tailed Hawk O 0.02 R Falco sparverius American Kestrel T 0.03 R Faico cohuvbarius Merlin WR? Grus canadensis * Sandhill Crane T? 0.07 R Actilis macularius Spotted Sandpiper WR 0.95 C Calidris minutilla Least Sandpiper WR 0.17 U Gailinago delicata Wilson's Snipe WR Zsiraicla asiatica White-winged Dove O? Ara mititaris + Military Macaw O? Megaceryle alcyon Belted Kingfisher WR 0.54 C Sphyrapicus varius Yellow-bellied WR 0.17 U Sapsucker Sphyrapicus nuchalis Red-naped Sapsucker WR 0.07 R Colaples auratus Northern Flicker WR 0.03 R Contopus cooperi Olive-sided Flycatcher T 0.14 R Coniopus sordidulus Western Wood-Pewee T 0.03 Contopus virens Eastern Wood-Pewee T Empidonax sp. Flycatcher T 0.07 R Empidonax minimus Least Flycatcher T Empidonax wrightii Gray Flycatcher WR Empidonax oberholseri Dusky Flycatcher T Sayornis phoebe Eastern Phoebe WR 1.90 C Sayornis saya Say's Phoebe WR Tyrannus forficatus Scissor-tailed T Flycatcher Lanius tudovicianus Loggerhead Shrike WR? 0.03 R Vireo vicinior Gray Vireo T? 0.07 R Vireo cttssinii Cassin's Vireo T 0.03 R Vireo solitarius Blue-headed Vireo WR 0.14 R Stelgidopteryx Northern Rough-winged serripennis Swallow WR/PR? 0.61 C Troglodytes aedon House Wren WR 0.78 C Cistothorus palustris Marsh Wren WR Regulus satrapa Golden-crowned Kinglet WR 0.24 U Regulus calendulu Ruby-crowned Kinglet WR 2.58 C Sialia sialis Eastern Bluebird WR 0.58 U Catltarus guttatus Hermit Thrush WR 0.03 R Turdus grayi + Clay-colored Robin O? Tardus migratorius American Robin WR Anthns rubescens American Pipit WR Bombycilla cedrorttm Cedar Waxwing T 0.48 C Vermivora celata Orange-crowned Warbler WR 0.41 U Vermivora ruficapilla Nashville Warbler T 0.14 R Dendroica petechia Yellow Warbler T 0.10 R Dendroica coronata Yellow-rumped Warbler WR 5.27 C Dendroica nigrescens Black-throated Gray T 0.03 R Warbler Dendroica virens Black-throated Green T 0.03 R Warbler Dendroica townsendi Townsend's Warbler T 0.07 R Dendroica occidentalis Hermit Warbler T Dendroica dominica Yellow-throated O 0.02 R Warbler Dendroica pinus Pine Warbler O 0.02 R Mniotilta varia Black-and-white WR 0.07 R Warbler Seiartts aurocapilla Ovenbird T 0.03 Seiurus noveborucensis Northern Waterthrush T Oporornis tolmiei * MacGillivray's Warbler T 0.03 R Wilsonia pusilla Wilson's Warbler WR 0.24 U Piranga ludoviciana Western Tanager T 0.14 R Spizella passerina Chipping Sparrow WR Spizella pallida Clay-colored Sparrow WR 0.03 R Spizella pusilla Field Sparrow WR 0.78 U Pooecetes gramineus Vesper Sparrow WR Passerculus Savannah Sparrow WR sandwichensis Melospiza melodia Song Sparrow WR? Melospiza lincolnii Lincoln's Sparrow WR 1.29 C Melospiza georgiana Swamp Sparrow WR 0.37 U Zonotrichia White-crowned Sparrow WR 0.24 U leucophrys Pheucticus Black-headed Grosbeak T melanocephalus Icterus galbula Baltimore Oriole T Carduelis pinus Pine Siskin T 0.14 R * Species under Mexican law protection (NOM-059-SE-MARNAT-2001, DOF 2002); # Species listed as threatened for Texas (TPWD 2003); + New records for Coahuila (RLivalcaba-Ortega & Gonzalez-Rojas 2009).
To demonstrate that the sampling effort generated species accumulation curves reached the asymptote, the EstimateS program (Colwell 2006) was used (Mao Tau's Model, Colwell et al. 2004). Log-normal (truncated) and log-series models were assessed for goodness-of-fit (Kolmogorov-Smirnov test) to the observed species abundance distribution of the whole community (e.g., Fisher et al. 1943; Preston 1948).
Density (D) was calculated as the number of birds per hectare. Frequency of occurrence (FO) was also obtained based on the percentage of point counts at which each species was observed. In both variables, a total of 443 point counts was considered for permanent residents and occasional species, 234 point counts for winter residents and transients (Oct-Mar), and 209 point counts for summer residents (Apr-Aug). In order to rank the species by dominance, two Olmstead-Tukey Diagrams were used for the whole community (Sokal & Rohlf 1995), one for species present during the breeding season (Apr-Aug) and one for those observed during the migratory-wintering season (Sep-Mar). The average values of FO and abundance (expressed as In + 1) are used as discriminators for four classes. Common (or dominant) species are those with values equal to or greater than abundance and FO averages. Frequent (or constant) species are those with a value less than the abundance average, but another equal to or greater than FO average. Uncommon (or occasional) species are those with a value less than the FO average, but another equal to or greater than abundance average. Finally, rare species are those with values less than both averages.
Olmstead-Tukey Diagrams were used to compare communities among sections during the breeding season. Also, for an unbiased comparison of number of species, rarefaction curves ([+ or -]95%CI; Mao Tau's Model, Colwell et al. 2004) were obtained for each section using Estimates (Colwell 2006). Finally, Shannon's Diversity Index (1948) and the Bray-Curtis Index of Similarity (1957) were calculated for each section and for the entire community.
RESULTS AND DISCUSSION
A total of 168 species were observed. Of these, 58 were considered as permanent residents, 32 as summer residents, 40 as winter residents, 30 as transients and nine as occasional. Eight confirmed and three potentially new breeding, and nine new non-breeding species were recorded for Coahuila (further discussed in Ruvalcaba-Ortega & Gonzalez-Rojas 2009), emphasizing the little attention previously given to this area. Fifteen of the species are under protection by Mexican laws (NOM-059-SEMARNAT-2001, DOF 2002), such as Muscovy Duck, Wood Stork, and Red-shouldered Hawk. In Texas as well, six of the species are listed as threatened for the state, e.g., White-faced Ibis, Gray Hawk, and Northern Beardless-Tyrannulet (TPWD 2003). Painted Bunting, a near threatened species on the Red List of Endangered Species (IUCN 2007), was also recorded as a common summer breeder in the area (Table 1). Based only on the systematic sampling effort, 126 species (75% of the total) were recorded and used for further quantitative analysis.
The accumulation curve of observed and expected species reached the asymptote assuring a representative sampling (Fig. 2). The species abundance distribution for the whole community was best fitted by the log-series distribution (D=0.035, P>0.05), which is suggested to be associated with a community dominated by one or a few factors (Magurran 2004). This would be expected for a restricted vegetation type, such as the riparian woodlands of northern Mexico, which are generally immersed in a matrix of semi-arid scrubland.
[FIGURE 2 OMITTED]
During the breeding season, 40 common, 12 uncommon, and 42 rare species were observed for the Rio Sabinas bird community (Table 1). The most dominant species were the Carolina Wren (D=5.28 birds/ha; A=173 inds.; FO=62.2%) and Golden-fronted Woodpecker (D=5.19 birds/ha; A= 198 inds.; FO=57.9%) as permanent residents, and Summer Tanager (D=6.36 birds/ha; A=167 inds.; FO=50.2%), as a summer breeder. During the migrating/wintering season, 21 common, 21 uncommon, and 59 rare species were observed (Table 2). The most dominant species were permanent residents such as the Carolina Wren (A=93 inds.; FO= 48.2%), Black-crested Titmouse and Northern Cardinal (both D=0.18 birds/ha; A=76 inds.; FO=39.8%), but wintering residents were also present among common species, e. g., Yellow-rumped Warbler (D=2.78 birds/ha; A=155 inds.; FO=26.5%) and Ruby-crowned Kinglet (D=1.37 birds/ha; A=76 inds.; FO=23.5%).
Important differences among communities were found when separating the analysis by sections. During the breeding season, MM (43 species, 694 individuals) showed the Carolina Wren (A=102 inds.; FO= 68%) and Summer Tanager (A=98 inds.; FO= 50%) as the dominant species; SJS (49 species, 800 individuals) also showed the Carolina Wren as the most dominant species (A=74 inds.; FO= 53.4%) but included the Golden-fronted Woodpecker (A=75 inds.; FO= 52.3%) as the second. On the other hand, S (58 species, 736 individuals) showed a community mostly dominated by the Golden-fronted Woodpecker (A=102 inds.; FO= 82.43%), a species that adjusts well to human-altered environments (Husak & Maxwell 1998). Also, the Painted Bunting was determined to be a common species only for the MM section (A=20 inds.; FO=14%), where as SJS (A=7 inds.; FO= 8%) and S (A=7 inds.; FO= 8.1%) included this species as uncommon (almost rare).
Rarefacted species richness for MM was significantly lower than SJS and S; however SJS and S were not distinct from one another (Fig. 3). A Kruskal-Wallis test among sections, comparing number of species and individuals per point count, showed highly significant differences in both cases (richness: [KW.sub.2,443] = 39.61, p< 0.01; abundance: [KW.sub.2,443] = 27.90, p< 0.01). A posterior Mann-Whitney test between each section showed satistically significant differences in all cases, showing the highest mean number of species and individuals for S, and the smallest for MM (Richness: MM vs. SJS, U=10332, p< 0.05; MM vs. S, U=5418, p< 0.01; SJS vs. S, U=6095, p< 0.01; abundance: MM vs. SJS, U=10196, p< 0.05; MM vs. S, U=5789, p< 0.01; SJS vs. S, U=6645, p< 0.01). Higher numbers of species and individuals in S could be a consequence of a more open habitat with better visibility and a higher detection rate. Also, a more fragmented habitat with a greater influence of arid scrubland species such as the Scissor-tailed Flycatcher, Loggerhead Shrike, and Pyrrhuloxia, which were recorded only in this section.
[FIGURE 3 OMITTED]
Using Bray-Curtis' Index, the highest value of similarity was obtained for the S and SJS sections (66.3%), followed by MM with S (63.7%) and SJS (63.5%). Diversity values showed the same pattern across sections, the highest was S (H' = 3.8, J' = 0.84), followed by SJS (H' = 3.6, J' = 0.83), and M (H' = 3.5, J'=0.82). The whole community showed a higher diversity (H'=3.8), but a slightly lower evenness (J'=0.79), than the individual sections.
Although the MM section did not show the highest value of diversity or evenness, nor the highest number of species or individuals per point count, its bird community shows important differences among species' dominances. It is also the best preserved section, and the one that shows the greatest regeneration of bald cypresses at all stages. In addition, it is the only section with the Painted Bunting as a common species, which had the highest number of individuals and frequency of occurrence. This is noteworthy because the species has shown a negative population trend (1966-2006) in the Breeding Bird Surveys of U. S. (Sauer et al. 2007). On the other hand, the consequences of habitat deterioration in S and SJS sections may not have been fully revealed yet, due to the longevity of Montezuma bald cypresses, causing a possible delay in the consequences of alteration of the riparian habitat for several decades (Rood & Mahoney 1993).
The Rio Sabinas is an important site for breeding (87) and migratory (72) birds. All of the breeding species of the Rio Sabinas are confirmed (82), probable (4), or possible (1) breeders for southern Texas (south of the 31st parallel; Benson & Arnold 2001, Lockwood & Freeman 2004). This was expected due to the fact that these rivers have similar riparian forests dominated by bald cypress, pecan and sycamore, especially in the Plateau Region such as the Nueces, West Nueces, Frio, and South Llano Rivers (El-Hage & Moulton 2007). In northeastern Mexico, as well, there are rivers dominated by bald cypresses such as the Rio Nazas in Durango and Coahuila, and the Rio Sabinas Hidalgo and Rio Ramos in Nuevo Leon; therefore, similarities in avian communities should be expected for these riparian habitats. Twenty-six of 35 common migrant species of the riparian systems of the southwestern U.S. (Skagen et al. 2005) were found in the area, highlighting its importance as a corridor and a stopover site. It is also noteworthy that migrants from both the eastern (i.e., Blue-headed Vireo, Yellow-throated, Pine and Black-throated Green warblers and Yellow-bellied Sapsucker) and western U.S. (i.e., Orange-crowned and Hermit warblers, and Red-naped Sapsucker) were recorded. Finally, these data should promote management plans leading to the conservation and restoration of the riparian habitats and water flow of the Rio Sabinas especially in the disturbed sections of San Juan de Sabinas (SJS) and Sabinas (S).
We thank the North American Wetlands Conservation Act for the funding provided to this research project (MX-N26E1) and the Consejo Ecologico de Participacion Ciudadana de la Region Carbonifera, A. C. (CEPACI) for facilitating the logistics of the fieldwork and the contact with local communities and owners.
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IR-O at: email@example.com
Irene Ruvalcaba-Ortega, Jose I. Gonzalez-Rojas and Ricardo Canales-del Castillo
Laboratorio de Biologia de la Conservation, Facultad de Ciencias Biologicas Vniversidad Autonoma de Nuevo Leon, Apartado Postal 25-F Cd. Universitaria, San Nicolas de los Garza Nuevo Leon, Mexico 66451
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|Author:||Ruvalcaba-Ortega, Irene; Gonzalez-Rojas, Jose I.; Castillo, Ricardo Canales-del|
|Publication:||The Texas Journal of Science|
|Date:||Nov 1, 2008|
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