Effects of habitat edges and nest-site characteristics on Painted Bunting nest success

Abstract

Declines in populations of Painted Buntings (Passerina ciris) over the past several decades have led to their recent classification as a species of conservation concern. To better assess their status, we investigated factors associated with productivity and abundance of a population in south-central Louisiana during 2010-2011. We monitored 41 Painted Bunting nests, 14 with video cameras, to identify predators, parasitism events, and improve nest success estimates. Vegetation measurements were also collected at nest sites and non-nest sites to quantify habitat characteristics. We used an information-theoretic approach to evaluate support for multiple models evaluating nest success. Highly supported models indicated large negative effects of Brown-headed Cowbird (Molothrus ater) parasitism, and positive effects of increased canopy cover and distance to habitat edge on daily survival rates. Our estimate of daily survival rate was 0.94 ± 0.03 and the probability of survival was 0.25 ± 0.02. Point-count data revealed that densities of Painted Buntings were greater in treeline habitats than in open scrub-shrub and mature forest edge habitats. Furthermore, treelines had higher densities of large trees (>23 cm dbh) and percent canopy cover, variables positively associated with nest success, than open scrub-shrub and forest edge habitats. In general, survival rates and causes of nest failure in southern Louisiana were similar to those determined for breeding populations of Painted Buntings at other sites. Our results suggest that treelines, despite having a high edge-to-area ratio, might be preferred nesting habitat for Painted Buntings in our study area. RESUMEN. Efecto de borde y de las características del lugar de anidamiento en eléxito reproductivo de Passerina cirisDescensos poblacionales del Gorrión Pintado (Passerina ciris), durante lasúltimas décadas, ha llevado a que la especie se considere una de preocupación. Para buscar la forma más apropiada de determinar su estatus, investigamos los factores asociados a la productividad y abundancia de una población en la parte sur-central de Luisiana, durante el 2010-2011. Monitoreamos, con cámaras de video, 41 nidos de el ave para identificar depredadores, parasitismo reproductivo y mejorar los estimados deléxito de anidamiento. Se tomaron datos sobre la vegetación en los lugares de construcción de nidos y lugares no utilizados para cuantificar las características del hábitat. Utilizamos un enfoque de información teórica para evaluar el apoyo de múltiples modelos aléxito de anidamiento. Los modelos con mayor apoyo indicaron efectos negativos del parasitismo reproductivo por parte del Tordo Pardo (Molothrus ater), y efecto positivo, en la supervivencia diaria, de un incremento en la cobertura del dosel y distancia al borde del hábitat. Nuestro estimado de sobrevivencia diaria fue de 0.94 ± 0.03 y la probabilidad de sobrevivir fue 0.25 ± 0.02. Conteos de punto revelaron que la densidad del gorrión era mayor en hábitat de líneas deárboles que en matorrales abiertos y bordes d...

Finer‐scale habitat predicts nest survival in grassland birds more than management and landscape: A multi‐scale perspective

“…Dickcissel nest survival responded to another nest‐site specific covariate, where nest survival decreased when nests were placed further from a non‐grassland edge. Previous studies have found depredation rates increase when nests are closer to habitat edges (Vasseur & Leberg, ), especially near shrubby or woody edges, where midsize mammalian predators appear to be more numerous (Winter, Johnson, & Faaborg, ). The reason we may have found this opposing trend for dickcissel was possibly due to not distinguishing between edge types (Schneider, Low, Arlt, & Pärt, ) when calculating distance to edge.…”

“…Other studies report nest-site and temporal variables often explained more variation in DSR compared to landscape or management variables alone (Adams, Burger, & Riffell, 2013;Lyons, Miller, Debinski, & Engle, 2015). Vegetation density and variance, and most importantly nest height, were positive predictors of blackbird nest survival during the incubation stage, but vegetation above the nest had negative effects on DSR during the nestling stage (Gillespie & Dinsmore, 2014 (Vasseur & Leberg, 2015), especially near shrubby or woody edges, where midsize mammalian predators appear to be more numerous (Winter, Johnson, & Faaborg, 2000). The reason we may have found this opposing trend for dickcissel was possibly due to not distinguishing between edge types (Schneider, Low, Arlt, & Pärt, 2012) when calculating distance to edge.…”

Avian Responses to Vegetation Changes From Post Oak Savanna Restoration Efforts in Eastern Texas

“…Generally, they select habitats with a high edge-to-area ratio with nearby open areas used as foraging sites (Vasseur & Leberg 2015), and occupy edges of tree clusters in otherwise open habitats (Kopachachena & Crist 2000).The mottes were unaltered during the restoration efforts, increasing the edge-to-area ratio at the restored sites. The Downloaded from http://meridian.allenpress.com/jfwm/article-pdf/doi/10.3996/JFWM-20-028/2785665/jfwm-20-028.pdf by guest on 15 March 2021 subsequent oak regeneration increased the woody growth at these sites that are used for singing perches by painted buntings.…”