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F. J. Vilella

Publications and source records attributed to F. J. Vilella.

10 recordsLinked to original sources
USGS2010

Landscape correlates along mourning dove call-count routes in Mississippi

Mourning dove (Zenaida macroura) call-count surveys in Mississippi, USA, suggest declining populations. We used available mourning dove call-count data to evaluate long-term mourning dove habitat relationships. Dove routes were located in the Mississippi Alluvial Valley, Deep Loess Province, Mid Coastal Plain, and Hilly Coastal Plain physiographic provinces of Mississippi. We also included routes in the Blackbelt Prairie region of Mississippi and Alabama, USA. We characterized landscape structure and composition within 1.64-km buffers around 10 selected mourning dove call-count routes during 3 time periods. Habitat classes included agriculture, forest, urban, regeneration stands, wetland, and woodlot. We used Akaike's Information Criterion to select the best candidate model. We selected a model containing percent agriculture and edge density that contained approximately 40% of the total variability in the data set. Percent agriculture was positively correlated with relative dove abundance. Interestingly, we found a negative relationship between edge density and dove abundance. Researchers should conduct future research on dove nesting patterns in Mississippi and threshold levels of edge necessary to maximize dove density. During the last 20 years, Mississippi lost more than 800,000 ha of cropland while forest cover represented largely by pine (Pinus taeda) plantations increased by more than 364,000 ha. Our results suggest observed localized declines in mourning dove abundance in Mississippi may be related to the documented conversion of agricultural lands to pine plantations.

Journal of Wildlife Management↗
USGS2005

Nesting ecology and behavior of Broad-winged Hawks in moist karst forests of Puerto Rico

The Puerto Rican Broad-winged Hawk (Buteo platypterus brunnescens) is an endemic and endangered subspecies inhabiting upland montane forests of Puerto Rico. The reproductive ecology, behavior, and nesting habitat of the Broad-winged Hawk were studied in Ri??o Abajo Forest, Puerto Rico, from 2001-02. We observed 158 courtship displays by Broad-winged Hawks. Also, we recorded 25 territorial interactions between resident Broad-winged Hawks and intruding Red-tailed Hawks (Buteo jamaicensis jamaicensis). Broad-winged Hawks displaced intruding Red-tailed Hawks from occupied territories (P = 0.009). Mayfield nest survival was 0.67 across breeding seasons (0.81 in 2001, N = 6; 0.51 in 2002, N = 4), and pairs averaged 1.1 young per nest (years combined). The birds nested in mixed species timber plantations and mature secondary forest. Nests were placed in the upper reaches of large trees emerging from the canopy. Nest tree DBH, understory stem density, and distance to karst cliff wall correctly classified (77.8%) nest sites. ?? 2005 The Raptor Research Foundation, Inc.

Journal of Raptor Research↗
USGS2005

Raptor abundance and distribution in the Llanos wetlands of Venezuela

The Llanos of Venezuela is a 275 000-km2 freshwater wetland long recognized as an important habitat for waterbirds. However, little information exists on the raptor community of the region. We conducted raptor surveys in the Southwestern and Western Llanos during 2000-02 and detected 28 species representing 19 genera. Overall, areas of the Llanos that we sampled contained 52% of all raptor species and more than 70% of the kites, buteos, and subbuteos known to inhabit Venezuela. Regional differences in the mean number per route for four of the 14 most common species, the Crested Caracara (Caracara plancus), Black-collared Hawk (Busarellus nigricollis), American Kestrel (Falco sparverius), and Osprey (Pandion haliaetus), were significant (P < 0.0018) in relation to the wet or dry seasons. Of the 14 less common species, six were detected in only one season (wet or dry). The Southwestern and Western regions of the Llanos support a rich raptor community composed primarily of nonmigratory wetland-dependent and upland-terrestrial species. ?? 2005 The Raptor Research Foundation, Inc.

Journal of Raptor Research↗
USGS2005

Effects of Hurricane Georges on habitat use by captive-reared Hispaniolan Parrots (Amazona ventralis) released in the Dominican Republic

We radio-tagged and released 49 captive-reared Hispaniolan Parrots (Amazona ventralis) in Parque Nacional del Este (PNE), Dominican Republic, during 1997 and 1998. Our primary objective was to develop a restoration program centered on using aviary-reared birds to further the recovery of the critically endangered Puerto Rican Parrot (A. vittata). Hurricane Georges made landfall over the release area on 22 September 1998 with sustained winds of 224 km/h, providing us with a unique opportunity to quantify responses of parrots to such disturbances. Quantitative data on such responses by any avian species are scarce, particularly for Amazona species, many of which are in peril and occur in hurricane-prone areas throughout the Caribbean. Mean home ranges of 18 parrots monitored both before and after the hurricane increased (P = 0.08) from 864 ha (CI = 689-1039 ha) pre-hurricane to 1690 ha (CI = 1003-2377 ha) post-hurricane. The total area traversed by all parrots increased > 300%, from 4884 ha pre-hurricane to 15,490 ha post-hurricane. Before Hurricane Georges, parrot activity was concentrated in coastal scrub, tall broadleaf forest, and abandoned agriculture (conucos). After the hurricane, parrots concentrated their activities in areas of tall broadleaf forest and abandoned conucos. Topographic relief, primarily in the form of large sinkholes, resulted in "resource refugia" where parrots and other frugivores foraged after the hurricane. Habitat use and movement patterns exhibited by released birds highlight the importance of carefully considering effects of season, topography, and overall size of release areas when planning psittacine restorations in hurricane-prone areas. ?? The Neotropical Ornithological Society.

Ornitologia Neotropical↗
USGS2005

Diversity and abundance of forest frogs (Anura: Leptodactylidae) before and after Hurricane Georges in the Cordillera Central of Puerto Rico

Caribbean hurricanes often impact terrestrial vertebrates in forested environments. On 21 September 1998, Hurricane Georges impacted Puerto Rico with sustained winds in excess of 166 km/hr, causing damage to forests of the island's principal mountain range; the Cordillera Central. We estimated forest frog abundance and diversity from call counts conducted along marked transects before and after Hurricane Georges in two forests reserves of the Cordillera Central (Maricao and Guilarte). We used distance sampling to estimate density of Eleutherodactylus coqui and recorded counts of other species. After the hurricane, the abundance of E. coqui increased in both reserves compared to prehurricane levels while abundance of other frog species decreased. In Maricao, relative abundance of E. richmondi (P = 0.013) and E. brittoni (P = 0.034) were significantly lower after the hurricane. Moreover, species richness and evenness of the Maricao and Guilarte frog assemblages declined after the hurricane. Our results on abundance patterns of the forest frog assemblages of Maricao and Guilarte Forests were similar to those reported from the Luquillo Experimental Forest after Hurricane Hugo in September 1989. Long-term demographic patterns of the forest frog assemblages in the Cordillera Central may be associated with changes due to the ecological succession in post-hurricane forests. Copyright 2005 College of Arts and Sciences.

Caribbean Journal of Science↗
USGS2003

Survival of captive-reared Hispaniolan Parrots released in Parque Nacional del Este, Dominican Republic

We report first-year survival rates of 49 captive-reared Hispaniolan Parrots ( Amazona ventralis ) released in Parque Nacional del Este, Dominican Republic. Our goal was to learn about factors affecting postrelease survival. Specifically, we tested if survival was related to movements and whether modifying prerelease protocols influenced survival rates. We also estimated survival in the aftermath of Hurricane Georges (22 September 1998). Twenty-four parrots, fitted with radio-transmitters, were released between 14 September and 12 December 1997. Twenty-five more were released between 29 June and 16 September 1998. First-year survival rates were 30% in 1997 and 29% in 1998. Survival probability was related to bird mobility. In contrast to birds released in 1997, none of the 25 parrots released in 1998 suffered early postrelease mortality (i.e., 3–5 days after release). Two adjustments to prerelease protocols (increased exercise and reduced blood sampling) made in 1998 may have contributed to differences in mobility and survival between years. The reduction of early postrelease mortality in 1998 was encouraging, as was the prospect for higher first-year survival (e.g., 30% to 65%). Only one death was attributed to the immediate impact of the hurricane. Loss of foraging resources was likely a major contributor to ensuing mortality. Birds increased their mobility, presumably in search of food. Survival rates dropped 23% in only eight weeks posthurricane. This study underscores the value of standardized prerelease protocols, and of estimating survival and testing for factors that might influence it. Inferences from such tests will provide the best basis to make adjustments to a release program.

Parque Nacional del Este↗
USGS2002

Nest poaching in Neotropical parrots

Although the poaching of nestlings for the pet trade is thought to contribute to the decline of many species of parrots, its effects have been poorly demonstrated. We calculated rates of mortality due to nest poaching in 23 studies of Neotropical parrots, representing 4024 nesting attempts in 21 species and 14 countries. We also examined how poaching rates vary with geographic region, presence of active protection programs, conservation status and economic value of a species, and passage of the U.S. Wild Bird Conservation Act. The average poaching rate across all studies was 30% of all nests observed. Thirteen studies reported poaching rates of ≥20%, and four reported rates openface> 70%. Only six studies documented no nest poaching. Of these, four were conducted on islands in the Caribbean region, which had significantly lower poaching rates than the mainland Neotropics. The other two studies that showed no poaching were conducted on the two species with the lowest economic value in our sample ( U.S. retail price). In four studies that allowed direct comparison between poaching at sites with active nest protection versus that at unprotected sites, poaching rates were significantly lower at protected sites, suggesting that active protection efforts can be effective in reducing nest poaching. In those studies conducted both before and after the passage of the U.S. Wild Bird Conservation Act, poaching rates were found to be significantly lower following its enactment than in the period before. This result supports the hypothesis that the legal and illegal parrot trades are positively related, rather than inversely related as has been suggested by avicultural interests. Overall, our study indicates that poaching of parrot nestlings for economic gain is a widespread and biologically significant source of nest mortality in Neotropical parrots.

Conservation Biology↗