Effects of Competition and Predation on Prothonotary Warblers and House Wrens Nesting in Eastern Iowa

In a fragmented midwestern floodplain forest, a small Prothonotary Warbler (Protonotaria citrea) population experienced high competition with House Wrens (Troglodytes aedon) and mammalian nest predation in 1988-89. Despite the provision of 3 types of nest boxes and higher water levels, Prothonotary Warblers did not nest successfully and decreased in the fragmented forest in 1990-91. House Wrens used \u3e90% of the nest boxes in both years. Wren territories doubled within the nestbox area, while remaining constant on an unmanipulated area. In contrast, a larger warbler population had high nesting success during 1990-91 in a relatively unfragmented, wetter forest tract. Such forests, which have lower wren densities and less predation pressure, may be crucial for Prothonotary Warbler populations in the Midwest

Range Expansions and New Breeding Records of Birds in Tamaulipas, Mexico

Breeding birds of riparian forests and other habitats in the Ciudad Victoria area were studied, mainly in June 2003 and 2006. Olivaceous woodcreeper (Sittasomus griseicapillus), mangrove swallow (Tachycineta albilinea), and scrub euphonia (Euphonia affinis; nesting) extended their range north to the Ciudad Victoria area. Western kingbird (Tyrannus verticalis) nested for the first time in Tamaulipas and occurred south to the Ciudad Victoria area, and European starlings (Sturnus vulgaris) nested in south-central Tamaulipas for the first time. Great curassow (Crax rubra) and crested guan (Penelope purpurascens) were rediscovered in the Ciudad Victoria area for the first time since 1909. Distributions of many species in the state of Tamaulipas are changing, as tropical species move north and temperate-zone species move south

Effects of Urbanization on Buff-bellied Hummingbirds in Subtropical South Texas

Urbanization and its associated processes affect wildlife in a variety of ways. Understanding how this increasing land use type affects biological communities is important for conservation efforts. Hummingbirds (family Trochilidae) are one taxon that has showed positive responses to varying intensities of urban development. We surveyed for Buff-bellied Hummingbird (Amazilia yucatanensis), a species on its northern range-limits, in urban woodlands, residential, natural, and revegetated habitats. We examined how urbanization is affecting Buff-bellied Hummingbird populations in South Texas with point-count surveys and GIS analysis. We found that Buff-bellied Hummingbirds had greater relative abundances in urban settings when compared with peri-urban habitats, and were more likely to be found with increasing impervious cover. Our results support the growing literature showing how, in some species, urbanization can have positive impacts

Changes in the breeding bird community of subtropical evergreen forest in the lower Rio Grande Valley of Texas, 1970s-1990s

Breeding-bird censuses conducted in 1994-1996 at the Santa Ana National Wildlife, southern Texas were compared to those done on the same site in 1973-1978. The study site was described as subtropical evergreen forest in the 1970s, but is now thorn-forest with remnant evergreen forest. Canopy cover was incomplete and lower and trees were smaller and more densely packed in 1994-1996 than in 1973-1978. Seven bird species typical of thorn-forest and thorn-scrub, which were not present in 1973-1978, made up 20% of the breeding bird community in 1994-1996. Species tolerant of thorn-forest and thorn-scrub made up 76.0% of the breeding bird community in 1994-1996, compared to 54.6% in 1973-1978. Three forest bird species disappeared from the study site. Water management will be needed if subtropical evergreen forest and its bird community are to be restored

Subspecific and breeding status of the Common Yellowthroat (Geothlypis trichas) at Santa Ana National Wildlife Refuge, Hidalgo County, Texas

ABSTRACT—We confirmed the breeding of the Common Yellowthroat (Geothlypis trichas) during 2008–2015 at Santa Ana National Wildlife Refuge and presented measurement evidence that individuals belong to the Brownsville Common Yellowthroat, Geothlypis trichas insperata. This expands the known breeding distribution for this rare and local subspecies. RESUMEN—Se confirm´o la reproducci´on de la mascarita com´un (Geothlypis trichas) durante 2008-2015 en Santa Ana National Wildlife Refuge y se presentaron pruebas de medici ´on que indican que los individuos pertenecen a la subespecie de mascarita com´un, Geothlypis trichas insperata. Esta informaci´on expande la distribuci´on de reproducci´on conocida de esta subespecie rara y local

Differential response by bronzed cowbirds to songs of potential hosts in the lower Rio Grande Valley of Texas

How bronzed cowbirds (Molothrus aeneus) find nests to parasitize is poorly known, especially whether they use host vocalizations as sources of information about nest location and status. We conducted 120 point-count surveys, followed by broadcasts of host songs, at Santa Ana National Wildlife Refuge in the Lower Rio Grande Valley of Texas in 2008 and 2009. Bronzed cowbirds responded to songs of potential host species by flying toward the source of the playback as single females or males or multiple females and males. Bronzed cowbirds responded in greater numbers to the songs of oriole species (Icterus) than to olive sparrow (Arremonops rufivirgatus), a lower-quality host species. Such responses by bronzed cowbirds could facilitate the location of host nests for nests of species difficult to find or to look into

Winter Site Fidelity of Orange-Crowned Warblers (Oreothlypis celata) in the Lower Rio Grande Valley of Texas

Abstract—We documented between-winter site fidelity of orange-crowned warblers (Oreothlypis celata) in the Lower Rio Grande Valley of Texas, between 2004 and 2017. Overall, we recaptured 13.9% of the 201 banded birds in ‡1 subsequent winter season: 20.8% of the 101 birds banded in urban natural areas, and 7.0% of the 100 banded in rural areas. We recaptured 8 birds ‡3 winters after their initial capture, indicating extended winter site fidelity. Resumen—Documentamos la fidelidad al sitio invernal de los chipes olivaceos (Oreothlypis celata) en el Valle del R´ıo Grande Baja de Texas entre 2004 y 2017. En general, se recaptur ´o el 13.9% de los 201 individuos anillados en al menos una temporada invernal posterior: el 20.8% de los 101 individuos anillados en las areas urbanas naturales, y el 7.0% de los 100 anillados en el ´area rural natural. Recapturamos 8 aves tres o m´as inviernos después de su captura inicial, lo que indica la fidelidad prolongada al sitio invernal

Response of Brood-Parasitic Bronzed Cowbird to Playback of the Song of Audubon\u27s Oriole

ABSTRACT—In the Lower Rio Grande Valley of South Texas, Audubon’s orioles (Icterus graduacauda) have declined substantially in the past 50 y, probably due to habitat loss, fragmentation, and brood parasitism by bronzed cowbirds (Molothrus aeneus). Tape playback of the song of Audubon’s oriole, originally intended to better survey the oriole, also attracted bronzed cowbirds. Bronzed cowbirds flew silently into the nearest tree in 14.1% of 234 playbacks, whereas Audubon’s orioles responded vocally or flew toward the recorder in 15.8% of playbacks. Bronzed cowbirds might use vocalizations of Audubon’s oriole as a cue to find breeding pairs or nests of this secretive species, which usually forages and sings within dense foliage. RESUMEN—En el Bajo Valle del Rı´o Grande del sur de Tejas, la poblacio´n de chorcha de cabeza negra (Icterus graduacauda) se ha disminuido de una manera substancial en los u´ltimos cincuenta an˜os. Esto se debe probablemente a la pe´rdida de habitats, fragmentacio´n, o quiza´s al empollamiento parasitario practicado por los pa´jaros vaqueros bronceados (Molothrus aeneus). Grabaciones emitidas del canto de la chorcha de cabeza negra, que inicialmente estaban destinadas a la inspeccio´n de estos pa´jaros, tambie´n llamaron la atencio´n de los vaqueros bronceados. Los resultados indicaron que los vaqueros bronceados volaron silenciosamente al a´rbol ma´s cercano en un 14.1% de las 234 emisiones de las grabaciones del canto de la chorcha de cabeza negra mientras que las chorchas de cabeza negra respondieron vocalmente o volaron hacia la fuente del sonido grabado en un 15.8% del total de las emisiones. Los pa´jaros vaqueros bronceados pueden usar sonidos de la chorcha de cabeza negra como una guı´a para encontrar pares de crı´a o nidos de esta especie de conducta reservada que se alimenta de forrajes y que canta en medio de densos follajes