Pre‐ to post‐fledging carryover effects and the adaptive significance of variation in wing development for juvenile songbirds

Jones, Teresa S.; Ward, Michael P.

doi:10.1111/1365-2656.13285

Cited by 32 publications

(61 citation statements)

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“…Evidence suggests food availability and agricultural landscapes can be influential to both nestling growth and condition, and yet has only recently received more attention as a possible driver of aerial insectivore declines (Smith and Bruun 1998, Granbom and Smith 2006, Pigeon et al 2013, Almasi et al 2015, Kusack et al 2020, Houle et al 2020). Therefore we assess the possibility that links between agricultural intensification and declining populations of aerial insectivores are not only through a reduction in the number of fledglings, but also through reduced offspring condition, as this may carry over and affect future recruitment and productivity (Stutchbury et al 2011, Naef-Daenzer and Grüebler 2016, Saino et al 2018, Evans et al 2020, Jones and Ward 2020).…”

Section: Introductionmentioning

confidence: 99%

Combined influence of food availability and agricultural intensification on a declining aerial insectivore

Garrett

Pelletier

Garant

et al. 2021

Preprint

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Aerial insectivores show worldwide population declines coinciding with shifts in agricultural practices. Increasing reliance on certain agricultural practices, is thought to have led to an overall reduction in insect abundance that negatively effects aerial insectivore fitness. The relationship between prey availability and the fitness of insectivores may thus vary with the extent of agricultural production. It is therefore imperative to quantify the strength and direction of these associations. Here we used data from an 11-year study monitoring the breeding of Tree swallows (Tachycineta bicolor) and the availability of Diptera (their main prey) across a gradient of agricultural intensification in southern Qu&eacutebec, Canada. More specifically, we evaluated the landscape characteristics affecting prey availability, and how this relationship influences the fledging success, the duration of the nestling period, the fledgling body mass and wing length as these variables are known to influence the population dynamics of this species. Diptera availability was greatest within predominately forested landscapes, yet within principally agricultural landscapes, it was greatest within ones dominated by intensive row crops (corn, soybean and wheat), and, counter to our predictions, lowest within those dominated by forage and pasture fields. Of the measured fitness proxies, only fledging success was positively related to prey availability. The impact of prey availability varied across the agricultural gradient as fledging success improved with increasing prey levels within forage landscapes yet declined in more agro-intensive landscapes. Finally, once conditioning on prey availability, fledging success was lowest, nestling periods were the longest, and wing length of fledglings were shortest within more agro-intensive landscapes. Our results highlight the interacting roles that aerial insect availability and agricultural intensification have on the fitness of aerial insectivores, and by extension how food availability may interact with other aspects of breeding habitats to influence the population dynamics of predators.

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Section: Introductionmentioning

confidence: 99%

Combined influence of food availability and agricultural intensification on a declining aerial insectivore

Garrett

Pelletier

Garant

et al. 2021

Preprint

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“…For many songbirds, parent-offspring conflict appears to mediate earlier fledging in response to higher risks of nest mortality, resulting in key tradeoffs between nest mortality risk and nestling period length observed across songbirds (7,8,40). These tradeoffs, in turn, appear to result in a series of events driving variation in trait development, pre-to postfledging carryover effects, postfledging bottlenecks, and differential postfledging survival which explain life history variation among species (17,18,22). Ultimately, our research highlights how incorporating estimates of fitness and theory on parent-offspring conflict can aid in improving our knowledge of the behavioral ecology of birds and other animals.…”

Section: Discussionmentioning

confidence: 90%

“…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.…”

Section: Methodsmentioning

confidence: 99%

“…After returning them to the nest, we placed a bag over the nestlings for 5 to 10 min, which was enough to calm them down and for them to remain in the nest. As a result, we had occasions where nestlings were force fledged, captured, processed, and then returned to the nest and were resampled (in the nest) the next day (18). To estimate postfledging survival, we tracked individuals every 1 to 3 d after they fledged using a handheld receiver and antenna.…”

Section: Methodsmentioning

confidence: 99%

“…As experimental and comparative postfledging work shows that songbird offspring benefit in terms of development and survival by staying in the nest longer (e.g., refs. 17,18), this raises an important question: If offspring are safer and benefit by staying in the nest, why then, do they fledge so early?…”

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confidence: 99%

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

Jones

Brawn

Ausprey

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Parent–offspring conflict has explained a variety of ecological phenomena across animal taxa, but its role in mediating when songbirds fledge remains controversial. Specifically, ecologists have long debated the influence of songbird parents on the age of fledging: Do parents manipulate offspring into fledging to optimize their own fitness or do offspring choose when to leave? To provide greater insight into parent–offspring conflict over fledging age in songbirds, we compared nesting and postfledging survival rates across 18 species from eight studies in the continental United States. For 12 species (67%), we found that fledging transitions offspring from comparatively safe nesting environments to more dangerous postfledging ones, resulting in a postfledging bottleneck. This raises an important question: as past research shows that offspring would benefit—improve postfledging survival—by staying in the nest longer: Why then do they fledge so early? Our findings suggest that parents manipulate offspring into fledging early for their own benefit, but at the cost of survival for each individual offspring, reflecting parent–offspring conflict. Early fledging incurred, on average, a 13.6% postfledging survival cost for each individual offspring, but parents benefitted through a 14.0% increase in the likelihood of raising at least one offspring to independence. These parental benefits were uneven across species—driven by an interaction between nest mortality risk and brood size—and predicted the age of fledging among species. Collectively, our results suggest that parent–offspring conflict and associated parental benefits explain variation in fledging age among songbird species and why postfledging bottlenecks occur.

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Context‐dependent carryover effects of hypoxia and warming in a coastal ecosystem engineer

Donelan

Breitburg

Ogburn

2021

Ecological Applications

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Organisms are increasingly likely to be exposed to multiple stressors repeatedly across ontogeny as climate change and other anthropogenic stressors intensify. Early life stages can be particularly sensitive to environmental stress, such that experiences early in life can "carry over" to have long-term effects on organism fitness. Despite the potential importance of these withingeneration carryover effects, we have little understanding of how they vary across ecological contexts, particularly when organisms are re-exposed to the same stressors later in life. In coastal marine systems, anthropogenic nutrients and warming water temperatures are reducing average dissolved oxygen (DO) concentrations while also increasing the severity of naturally occurring daily fluctuations in DO. Combined effects of warming and diel-cycling DO can strongly affect the fitness and survival of coastal organisms, including the eastern oyster (Crassostrea virginica), a critical ecosystem engineer and fishery species. However, whether early life exposure to hypoxia and warming affects oysters' subsequent response to these stressors is unknown. Using a multi-phase laboratory experiment, we explored how early life exposure to diel-cycling hypoxia and warming affected oyster growth when oysters were exposed to these same stressors eight weeks later. We found strong, interactive effects of early life exposure to diel-cycling hypoxia and warming on oyster tissue:shell growth, and these effects were context-dependent, only manifesting when oysters were exposed to these stressors again two months later. This change in energy allocation based on early life stress exposure may have important impacts on oyster fitness. Exposure to hypoxia and warming also influenced oyster tissue and shell growth, but only later in life. Our results show that organisms' responses to current stress can be strongly shaped by their previous stress exposure, and that contextdependent carryover effects may influence the fitness, production, and restoration of species of management concern, particularly for sessile species such as oysters.

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Pre‐ to post‐fledging carryover effects and the adaptive significance of variation in wing development for juvenile songbirds

Cited by 32 publications

References 58 publications

Combined influence of food availability and agricultural intensification on a declining aerial insectivore

Combined influence of food availability and agricultural intensification on a declining aerial insectivore

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

Context‐dependent carryover effects of hypoxia and warming in a coastal ecosystem engineer

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