Falling through the policy cracks: implementing a roadmap to conserve aerial insectivores in North America

Nebel, Silke; Casey, James P.; Cyr, Marc-André; Kardynal, Kevin J.; Krebs, Elizabeth; Purves, Elisabeth; Bélisle, Marc; Brigham, R. Mark; Knight, Elly C.; Morrissey, Christy A.; Clark, Robert G.

doi:10.5751/ace-01618-150123

Cited by 10 publications

(3 citation statements)

References 15 publications

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“…Globally, many aerial insectivores have declined in abundance since the mid‐1980s, with steep declines documented for many insectivorous birds (Bowler et al, 2019 ; Nebel et al, 2011 , 2020 ; Powell et al, 2015 ). Declining insect prey has been proposed as a primary driver of the concomitant decline of several avian aerial insectivores (Cox et al, 2019 ; Spiller & Dettmers, 2019 ), but the evidence is equivocal and declines are likely to be multifactorial, with the relative impact of specific factors varying among species (Michel et al, 2016 ).…”

Section: Introductionmentioning

confidence: 99%

Rapidly declining body size in an insectivorous bat is associated with increased precipitation and decreased survival

Davy

Zuben

Kukka

et al. 2022

Ecological Applications

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Reduced food availability is implicated in declines in avian aerial insectivores, but the effect of nutritional stress on mammalian aerial insectivores is unclear. Unlike birds, insectivorous bats provision their young through lactation, which might protect nursing juveniles when prey availability is low but could increase the energetic burden on lactating females. We analyzed a 15-year capture-mark-recapture data set from 5312 individual little brown myotis (Myotis lucifugus) captured at 11 maternity colonies in northwestern Canada, to test the hypothesis that nutritional stress is impacting these mammalian aerial insectivores. We used long-bone (forearm [FA]) length as a proxy for relative access to nutrition during development, and body mass as a proxy for access to nutrition prior to capture. Average FA length and body mass both decreased significantly over the study period in adult females and juveniles, suggesting decreased access to nutrition. Effect sizes were very small, similar to those reported for declining body size in avian aerial insectivores. Declines in juvenile body mass were only observed in individuals captured in late summer when they were foraging independently, supporting our hypothesis that lactation provides some protection to nursing young during periods of nutritional stress. Potential drivers of the decline in bat size include one or both of (1) declining insect (prey) abundance, and (2) declining prey availability. Echolocating insectivorous bats cannot forage effectively during rainfall, which is increasing in our study area. The body mass of captured adult females and juveniles in our study was lower, on average, after periods of high rainfall, and higher after warmer-than-average periods. Finally, survival models revealed a positive association between FA length and survival, suggesting a fitness consequence to declines in body size. Our study area has not yet been impacted by bat white-nose syndrome (WNS), but research elsewhere has suggested that fatter bats are more likely to survive infection. We found evidence for WNSindependent shifts in the body size of little brown myotis, which can inform

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Section: Introductionmentioning

confidence: 99%

Rapidly declining body size in an insectivorous bat is associated with increased precipitation and decreased survival

Davy

Zuben

Kukka

et al. 2022

Ecological Applications

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“…A variety of vertebrate taxa are well known for having a dire conservation status, including but not limited to lemurs, grassland/aerial insectivorous birds, and various amphibians, especially frogs (Grenyer et al 2006;Herkert et al 2003;Morrison et al 2012;Brown et al 2015;Nebel et al 2020). The reasons for the conservation concern, for these and other species is varied, but a reduction in specific resources, limited distribution range, habitat loss due to human activities, active persecution, and climate change, have all been identified and are often the focus of conservation related research.…”

Section: Introductionmentioning

confidence: 99%

A career of bat research: informing and motivating bat conservation

Brigham

Wee

2023

Can. J. Zool.

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Bat conservation has become prevalent over the last few decades due to critical population declines worldwide. Our purpose was to assess whether Brock Fenton’s research career coincided with increasing bat conservation research in Canada and North America. Fenton has made significant contributions to bat research during a long and productive publishing career accompanied by participation in research organizations like the North American Society for Bat Research and the Natural Sciences and Engineering Research Council. His conservation research as well as efforts to raise public awareness about these animals has coincided with work for the Committee on the Status of Endangered Wildlife in Canada and its equivalent (CASSARO) in Ontario. To assess the impact of his career, we quantified the relative amount of his peer reviewed publications with a conservation focus and compared this with the level of conservation related presentations at annual NASBR conferences. In the same manner, we assessed how often conservation focused applications were funded by the Ecology and Evolution section of the NSERC Discovery grant program. Although it cannot be said with authority that Fenton actually initiated the increase in bat conservation research, our results indicate that his research efforts coincide with and presumably had considerable influence in driving this area of research.

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“…Over the 50-year period from 1966 to 2006, birds that feed on flying insects, or aerial insectivores, showed the strongest declines of any songbird group in North America, with long-distance migrants (to South America) showing the most acute negative trends (Nebel et al, 2010;Smith et al, 2015;Rosenberg et al, 2019). To halt these widespread declines, we need policies that identify and minimize loss of critical habitat, account for climate change, and fully integrate biodiversity goals (Butchart et al, 2010;Favaro et al, 2014;Nebel et al, 2020). Such policies can be developed quantitatively by using avian habitat models in landscape simulations to project future habitat conditions under a range of land-use scenarios and natural disturbance events (Mahon et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Forecasting the Cumulative Effects of Multiple Stressors on Breeding Habitat for a Steeply Declining Aerial Insectivorous Songbird, the Olive-sided Flycatcher (Contopus cooperi)

et al. 2021

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To halt ongoing loss in biodiversity, there is a need for landscape-level management recommendations that address cumulative impacts of anthropogenic and natural disturbances on wildlife habitat. We examined the cumulative effects of logging, roads, land-use change, fire, and bark beetle outbreaks on future habitat for olive-sided flycatcher (Contopus cooperi), a steeply declining aerial insectivorous songbird, in Canada’s western boreal forest. To predict the occurrence of olive-sided flycatcher we developed a suite of habitat suitability models using point count surveys (1997–2011) spatially- and temporally-matched with forest inventory data. Flycatcher occurrence was positively associated with small (∼10 ha) 10- to 20-year-old clearcuts, and with 10–100% tree mortality due to mountain pine beetle (Dendroctonus ponderosae) outbreaks, but we found no association with roads or distance to water. We used the parameter estimates from the best-fit habitat suitability models to inform spatially explicit state-and-transition simulation models to project change in habitat availability from 2020 to 2050 under six alternative scenarios (three management × two fire alternatives). The simulation models projected that the cumulative effects of land use conversion, forest harvesting, and fire will reduce the area of olive-sided flycatcher habitat by 16–18% under Business As Usual management scenarios and by 11–13% under scenarios that include protection of 30% of the land base. Scenarios limiting the size of all clearcuts to ≤10 ha resulted in a median habitat loss of 4–6%, but projections were highly variable. Under all three management alternatives, a 50% increase in fire frequency (expected due to climate change) exacerbated habitat loss. The projected losses of habitat in western boreal forest, even with an increase in protected areas, imply that reversing the ongoing population declines of olive-sided flycatcher and other migratory birds will require attention to forest management beyond protected areas. Further work should examine the effects of multiple stressors on the demographic mechanisms driving change in aerial insectivore populations, including stressors on the wintering grounds in South America, and should aim to adapt the design of protected areas and forest management policies to projected climate-driven increases in the size and frequency of wildfires.

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Falling through the policy cracks: implementing a roadmap to conserve aerial insectivores in North America

Cited by 10 publications

References 15 publications

Rapidly declining body size in an insectivorous bat is associated with increased precipitation and decreased survival

Rapidly declining body size in an insectivorous bat is associated with increased precipitation and decreased survival

A career of bat research: informing and motivating bat conservation

Forecasting the Cumulative Effects of Multiple Stressors on Breeding Habitat for a Steeply Declining Aerial Insectivorous Songbird, the Olive-sided Flycatcher (Contopus cooperi)

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