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Abstract Understanding the demographic drivers of range contractions is important for predicting species' responses to climate change; however, few studies have examined the effects of climate change on survival and recruitment across species' ranges. We show that climate change can drive trailing edge range contractions through the effects on apparent survival, and potentially recruitment, in a migratory songbird. We assessed the demographic drivers of trailing edge range contractions using a long‐term demography dataset for the black‐throated blue warbler (Setophaga caerulescens) collected across elevational climate gradients at the trailing edge and core of the breeding range. We used a Bayesian hierarchical model to estimate the effect of climate change on apparent survival and recruitment and to forecast population viability at study plots through 2040. The trailing edge population at the low‐elevation plot became locally extinct by 2017. The local population at the mid‐elevation plot at the trailing edge gradually declined and is predicted to become extirpated by 2040. Population declines were associated with warming temperatures at the mid‐elevation plot, although results were more equivocal at the low‐elevation plot where we had fewer years of data. Population density was stable or increasing at the range core, although warming temperatures are predicted to cause population declines by 2040 at the low‐elevation plot. This result suggests that even populations within the geographic core of the range are vulnerable to climate change. The demographic drivers of local population declines varied between study plots, but warming temperatures were frequently associated with declining rates of population growth and apparent survival. Declining apparent survival in our study system is likely to be associated with increased adult emigration away from poor‐quality habitats. Our results suggest that demographic responses to warming temperatures are complex and dependent on local conditions and geographic range position, but spatial variation in population declines is consistent with the climate‐mediated range shift hypothesis. Local populations of black‐throated blue warblers near the warm‐edge range boundary at low latitudes and low elevations are likely to be the most vulnerable to climate change, potentially leading to local extirpation and range contractions.
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Demography across latitudinal and elevational gradients for range-expanding whelks
Marine species worldwide are responding to ocean warming by shifting their ranges to new latitudes and, for intertidal species, elevations. Demographic traits can vary across populations spanning latitudinal and elevational ranges, with impacts on population growth. Understanding how demography varies across gradients from range center to edge could help us predict future shifts, species assemblages, and extinction risks. We investigated demographic traits for 2 range-expanding whelk species:Acanthinucella spirataandMexacanthina lugubris.We measured reproductive output across environmental (latitudinal and shore elevation) gradients along the coast of California, USA. We also conducted intensive measurements of offspring condition (survival and thermal tolerance) across shore elevation forM. lugubrisat one site. We found no difference in reproductive output, body size, or larval survival across shore heights forM. lugubris,suggesting that egg-laying behavior buffers developing stages from the relatively high level of thermal variation experienced due to daily tidal emersion. However, across latitudes, reproductive output increased toward the leading range edge forA. spirata, and body size increased for both species. Increased vital rates at the leading range edge could increase whelk population growth and expansion, allowing species to persist under climate change even if contractions occur at trailing edges.
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- Award ID(s):
- 1852060
- PAR ID:
- 10515642
- Publisher / Repository:
- MEPS
- Date Published:
- Journal Name:
- Marine Ecology Progress Series
- Volume:
- 728
- ISSN:
- 0171-8630
- Page Range / eLocation ID:
- 115 to 121
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3354/meps14349
