Resumen. examinamos la ecología de nidificación de Euphagus carolinus a través del monitoreo de 162 nidos para obtener datos de supervivencia de nidos en alaska y de 252 registros adicionales de alaska y canadá para identificar habitats importantes para la nidificación y evaluar si las bajas tasas de éxito de nidos contribuyeron a las disminuciones poblacionales en alaska. en la costa de alaska y a lo largo de canadá, los nidos se encontraron principalmente en coníferas (85% de 212 nidos). todos los nidos en coníferas de alaska y el 80% de los de canadá estuvieron ubicados en ejemplares de Picea spp., principalmente P. mariana. en alaska se identificó un uso selectivo de ejemplares pequeños de Picea (<8 cm dap), resultando en un alto éxito reproductivo-la supervivencia de los nidos incrementó con la densidad de P. mariana, y el éxito de nidos en ejemplares de Picea (79%) fue mayor que el de los nidos ubicados en vegetación decidua (52%). la supervivencia de nidos en ejemplares más altos de Picea disminuyó, posiblemente debido a la depredación por parte de Tamiasciurus hudsonicus. los individuos de E. carolinus nidificaron cerca del agua en el interior (x _ = 8 m) y en el sur centro de alaska (x _ = 30 m), y los ejemplares pequeños de Picea parecieron ser importantes dentro de la mayor parte del área de distribución de la especie. Sin embargo, en el interior de alaska, la mayoría de los nidos se ubicaron en ejemplares de Salix (78%), los que dominaban la vegetación cercana al agua. el éxito de nidos en alaska promedió el 56%, similar a las tasas del mismo periodo en nueva inglaterra pero mayor que las de otras especies de Euphagus de américa del norte. Son necesarios estudios para verificar si la supervivencia de nidos es alta también en canadá y para investigar dónde y cómo el déficit en la supervivencia de adultos o juveniles puede estar limitando el crecimiento poblacional.neSting ecology of the RuSty BlackBiRd in alaSka and canada ecología de nidificación de Euphagus carolinus en alaska y canadá Abstract. we examined the nesting ecology of the Rusty Blackbird (Euphagus carolinus) from 162 nests monitored for nest survival in alaska and 252 incidental records from alaska and canada to identify important habitats for nesting and to test whether low rates of nest success are contributing to populations declines in alaska. in coastal alaska and throughout canada, nests were primarily in conifers (85% of 212 nests). all conifer nests in alaska and 80% of those in canada were placed in spruce (Picea spp.), primarily black spruce (P. mariana). in alaska use of small spruces (<8 cm dbh) was selective and resulted in high reproductive success-nest survival increased with black spruce density, and success of nests in spruce (79%) was higher than that of nests in deciduous vegetation (52%). Survival of nests in taller spruce declined, possibly from predation by red squirrels (Tamiasciurus hudsonicus). Rusty Blackbirds nested near water in interior (x _ = 8 m) and south-central alaska (x _ = 30 m), and small spruces near ...
Abstract. Aging birds often relies on differences in plumage between immatures and adults, and understanding these patterns can improve our ability to discern demographic patterns within populations. We investigated patterns of prebasic molt of the Rusty Blackbird (Euphagus carolinus) in fall at Whitehorse, Yukon Territory, and developed a new technique for aging based on characteristics of the head plumage acquired during prebasic molt. Furthermore, we investigated the possibility of a prealternate molt among wintering Rusty Blackbirds on the basis of captures in Mississippi and museum specimens from across the species' winter range. Finally, we examined how a prealternate molt might affect the aging of winter birds by plumage. Rusty Blackbirds completed their prebasic molt by the end of September, and immature birds had a more prominent eye ring and a paler chin than adults, allowing a reliable age determination. Previously, the Rusty Blackbird was thought to attain its breeding plumage through feather wear exclusively, but we discovered a partial prealternate molt in our examinations of live captures (76% molting) and museum specimens (59% molting). The prealternate molt was observed in all age and sex classes, was concentrated along the feather tracts of the head, and peaked in occurrence from mid-February to mid-March, when nearly 90% of birds were molting. Between mid-December and mid-February, the prealternate molt did not appear to interfere with aging birds in the hand by the pattern of the eye ring and chin in basic plumage. Age determination later in the spring, however, remains to be investigated.Key words: age determination, Euphagus carolinus, Icteridae, molt limit, prealternate molt, prebasic molt, Rusty Blackbird. Implicancias de la Muda Prebasica y de la Previamente No Descripta Muda Prealterna para Determinar la Edad de Euphagus carolinusResumen. La determination de la edad de las aves a menudo se realiza a partir de diferencias de plumaje entre individuos inmaduros y adultos. Entender estos patrones puede mejorar nuestra capacidad de distinguir patrones demograficos dentro de las poblaciones. Investigamos patrones de muda prebasica de Euphagus carolinus durante el otono en Whitehorse, Territorio Yukon, y desarrollamos una nueva tecnica para determinar la edad basada en las caracteristicas de las plumas de la cabeza adquiridas durante la muda prebasica. Ademas, investigamos la posibilidad de una muda prealterna entre individuos de E. carolinus invernantes basandonos en capturas en Mississippi y en especimenes de museo del rango de distribution de invierno de la especie. Finalmente, examinamos como una muda prealterna podria afectar la determination de la edad de las aves invernales a partir del plumaje. E. carolinus completa su muda prebasica para fines de septiembre, y las aves inmaduras tienen un anillo ocular mas prominente y una barbilla mas palida que los adultos, permitiendo una determination confiable de la edad. Anteriormente, se pensaba que E. carolinus alcanzaba su plumaje nuptial exc...
Bank Swallow (<i>Riparia riparia</i>) is a declining insectivorous bird that nests colonially in near-vertical surfaces, including natural banks along waterways as well as those created by industrial excavation. Several threats are likely contributing to the population decline, conservation measures have been recommended, and monitoring methods have been developed. However, little is known of this species in the extensive boreal portion of its breeding range. To assess whether recommendations developed in southern areas are likely to be effective in a more northerly region, we investigated aspects of the nesting ecology of Bank Swallow in southern Yukon during 2013–2017. Nesting activity occurred between 20 May and 21 August. We found an exceptional abundance of nest burrows in natural riverbanks along 46 km of the Yukon River near Whitehorse (326 burrows/km), but relatively low percent burrow occupancy in both natural and artificial habitats compared to studies from other regions. Year-to-year persistence of nest burrows and rates of reuse of burrows were high compared to other studies. We highlight the potential importance of the boreal region for recovery of Bank Swallow in Canada, and the importance of using region-specific estimates of percent occupancy when monitoring Bank Swallow using burrow counts. Further study is needed to determine whether unoccupied burrows contribute to nesting success, and whether there are situations in which Bank Swallow burrows should be protected year-round instead of only during nesting.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.