Postfledging survival of the Worthington's Marsh Wren (Cistothorus palustris griseus)

Abstract

The postfledging period of a passerine bird's life is increasingly recognized as an understudied component of songbird conservation, because the habitat needs of fledglings can differ from nesting adults and survivorship during this period can substantially affect population growth rates. We studied postfledging survival of the Worthington's Marsh Wren (Cistothorus palustris griseus), a state-listed salt marsh songbird subspecies in northeastern Florida, USA, during 2016-2017. Postfledging survival was low during the first 21 d following fledging for the cohort of tracked birds (0.10; 95% confidence interval: 0.01, 0.37). The top a priori model indicated that heavier birds at the time of tagging exhibited greater survival than lighter birds, and birds from larger broods had greater survival than birds from smaller broods. Other covariates not in the top model that also influenced survival included the amount of tall-form smooth cordgrass (Spartina alterniflora) within the natal patch, which positively influenced survival, and the amount of black needlerush (Juncus roemerianus) within the natal patch, which negatively affected survival. The low rates of postfledging survival combined with low rates of nest survival reported elsewhere indicate that Worthington's Marsh Wrens in northeastern Florida require continued protection and warrant further research into management and restoration activities that will improve their habitat. Survie suivant l'envol du nid chez le Troglodyte des marais de Worthington (Cistothorus palustris griseus)RÉSUMÉ. La période suivant l'envol du nid dans la vie d'un passereau est de plus en plus reconnue comme une composante sousétudiée de la conservation des oiseaux chanteurs, parce que les besoins en matière d'habitat des jeunes suivant l'envol sont peut-être différents de ceux des adultes nicheurs et la survie durant cette période peut grandement affecter les taux de croissance des populations. Nous avons étudié la survie suivant l'envol du nid du Troglodyte des marais de Worthington (Cistothorus palustris griseus), une sousespèce de passereau de marais salés désignée au niveau de l'État dans le nord-est de la Floride, États-Unis, en 2016 et 2017. Le taux de survie suivant l'envol du nid était faible durant les 21 jours suivant l'envol chez la cohorte d'oiseaux suivis (0,10; intervalle de confiance à 95 % : 0,01-0,37). Le meilleur modèle a priori a indiqué que les oiseaux plus lourds au moment du marquage avaient une meilleure survie que les oiseaux plus légers, et les oiseaux provenant de couvées plus nombreuses avaient un meilleur taux de survie que les oiseaux issus de couvées moins nombreuses. Les autres covariables ayant un effet sur la survie, mais non inclues dans le meilleur modèle a priori, comprenaient la quantité de spartine alterniflore (Spartina alterniflora) de forme haute dans la parcelle abritant le nid, qui avait un effet positif sur la survie, et la quantité de jonc (Juncus roemerianus) dans la parcelle abritant le nid, qui avait un effet négatif sur la survie. Le faibl...

Habitat selection of nesting and fledgling salt marsh songbirds in northeast Florida

“…Both wren and sparrow nests were associated with taller vegetation and higher stem counts, and nesting wrens and wren fledglings used tall cordgrass more often than short cordgrass, though use of tall cordgrass in fledglings declined as they aged (Figure 6A). Habitat needs of birds can vary across life stages, yet wren fledglings generally stayed close to their natal territories (Cox et al 2019) and selected similar vegetation features to those of nesting adults. Consistent with our predictions, fledglings somewhat shifted away from tall, dense cordgrass as they aged.…”

“…Daily survival of sparrow nests was not associated with any of these habitat features, but there was no way to test the effect of needlerush because we did not find any sparrow nests in needlerush despite extensive searching. Post‐fledging survival for wrens was positively associated with tall cordgrass and negatively associated with needlerush (Cox et al 2019), but again other factors such as weight at tagging had a stronger effect on daily survival. It is likely that we would also see similar patterns of survival and vegetation use by sparrow fledglings, though we were unable to test these assumptions.…”

Fledgling Bachman’s Sparrows in a longleaf pine ecosystem: survival, movements, and habitat selection

“…Predation by snakes was the leading cause of mortality for fledgling Bachman’s Sparrows in our study, when cause of mortality could be identified. Snakes can be the largest organismal clade predating fledgling songbirds (Suedkamp Wells et al 2007, Giovanni et al 2015, Lehman 2017, Young et al 2019) or just one of many clades contributing to predation events (Kershner et al 2004, Jackson 2010, Cox et al 2019). Although relatively few studies of survival of fledgling songbirds have been conducted in the southeastern United States, Lehman (2017) found that snakes accounted for over half of all known predations events on Golden‐winged Warblers ( Vermivora chrysoptera ) in the Cumberland Mountains of Tennessee.…”

Parental benefits and offspring costs reflect parent–offspring conflict over the age of fledging among songbirds

“…Though data for our study were derived from 18 species in eight different locations, methodologies were consistent across studies, with only a few minor differences in field techniques [see SI Appendix, Table S1 for full species list and associated studies (18,27,28,(45)(46)(47)(48)(49)(50) for more details]. For each species, trained field assistants searched for and monitored nests across the breeding season by systematic searching and observing adult behaviors.…”

“…Data Availability. Data for this research are available through previously published manuscripts, dissertations, and theses (18,27,28,(45)(46)(47)(48)(49)(50), and the Supporting Information.…”