Pre-fledging quality and recruitment in an aerial insectivore reflect dynamics of insects, wetlands and climate

Oecologia ◽  
2021 ◽  
Author(s):  
Lisha L. Berzins ◽  
Andie K. Mazer ◽  
Christy A. Morrissey ◽  
Robert G. Clark
Keyword(s):  
Aerial Insectivore

Phenotypic differences among wild passerine nestlings in relation to early-life rearing environment

2021 ◽  
Author(s):  
Jesús Gómez ◽  
Christy Morrissey ◽  
Sonia Cabezas ◽  
Tracy Marchant ◽  
Robert Clark
Keyword(s):  
Land Use ◽  
Body Condition ◽  
Early Life ◽  
Agricultural Land ◽  
Developmental Stages ◽  
Tree Swallow ◽  
Phenotypic Differences ◽  
Aerial Insectivore ◽  
Fledgling Survival ◽  
Insect Populations

Subtle changes in stress physiology during critical developmental stages have been linked to long-term fitness; however, the biological processes and phenotypic responses to early-life rearing environments such as anthropogenic land use conditions, have not been fully evaluated in insectivorous birds. We manipulated Tree Swallow, Tachycineta bicolor (Vieillot, 1808), brood sizes at sites with contrasting agricultural land use to assess phenotypic changes in body condition and genetic and physiological biomarkers of stress during the sensitive nestling growth phase. We predicted that nestling swallows raised on cropland-dominated sites, especially those in enlarged broods, would have lower body condition, shorter telomeres, and higher feather corticosterone than nestlings raised in smaller broods at grassland sites. Body condition was highest among nestlings raised in reduced broods but was unrelated to land use. Telomere lengths tended to be shorter in nestlings from enlarged broods and at cropland sites. Corticosterone was not related to any factor. Locally-abundant insect populations associated with wetlands may have dampened the effects and/or parent swallows assumed higher costs of reproduction rather than passing these costs to nestlings. Results suggest that food stress could reduce fledgling survival via telomere shortening; a hypothesis that requires further investigation due to its potential importance to population viability in multiple declining aerial insectivore species.

scholarly journals Omega-3 long-chain polyunsaturated fatty acids support aerial insectivore performance more than food quantity

2016 ◽  
Vol 113 (39) ◽  
pp. 10920-10925 ◽  
Author(s):  
Cornelia W. Twining ◽  
J. Thomas Brenna ◽  
Peter Lawrence ◽  
J. Ryan Shipley ◽  
Troy N. Tollefson ◽  
...  
Keyword(s):  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Tree Swallow ◽  
Omega 3 ◽  
Food Quantity ◽  
Aerial Insectivore ◽  
Aerial Insectivores ◽  
Terrestrial Insects ◽  
Long Chain

Once-abundant aerial insectivores, such as the Tree Swallow (Tachycineta bicolor), have declined steadily in the past several decades, making it imperative to understand all aspects of their ecology. Aerial insectivores forage on a mixture of aquatic and terrestrial insects that differ in fatty acid composition, specifically long-chain omega-3 polyunsaturated fatty acid (LCPUFA) content. Aquatic insects contain high levels of both LCPUFA and their precursor omega-3 PUFA, alpha-linolenic acid (ALA), whereas terrestrial insects contain much lower levels of both. We manipulated both the quantity and quality of food for Tree Swallow chicks in a full factorial design. Diets were either high-LCPUFA or low in LCPUFA but high in ALA, allowing us to separate the effects of direct LCPUFA in diet from the ability of Tree Swallows to convert their precursor, ALA, into LCPUFA. We found that fatty acid composition was more important for Tree Swallow chick performance than food quantity. On high-LCPUFA diets, chicks grew faster, were in better condition, and had greater immunocompetence and lower basal metabolic rates compared with chicks on both low LCPUFA diets. Increasing the quantity of high-LCPUFA diets resulted in improvements to all metrics of performance while increasing the quantity of low-LCPUFA diets only resulted in greater immunocompetence and lower metabolic rates. Chicks preferentially retained LCPUFA in brain and muscle when both food quantity and LCPUFA were limited. Our work suggests that fatty acid composition is an important dimension of aerial insectivore nutritional ecology and reinforces the importance of high-quality aquatic habitat for these declining birds.

scholarly journals Interacting effects of cold snaps, rain, and agriculture on the fledging success of a declining aerial insectivore

2021 ◽  
Author(s):  
Daniel Roy Garrett ◽  
Fanie Pelletier ◽  
Dany Garant ◽  
Marc Bélisle
Keyword(s):  
Climate Change ◽  
Agricultural Intensification ◽  
Prey Availability ◽  
Tree Swallow ◽  
Landscape Changes ◽  
Population Declines ◽  
Negative Effects ◽  
Fledging Success ◽  
Inclement Weather ◽  
Aerial Insectivore

Climate change predicts the increased frequency, duration, and intensity of inclement weather periods, such as unseasonably low temperatures and prolonged precipitation. Many migratory species have advanced the phenology of important life history stages, and as a result are likely exposed to these periods of inclement spring weather more often, thus risking reduced fitness and population growth. For declining avian species, including aerial insectivores, anthropogenic landscape changes such as agricultural intensification are another driver of population declines. These landscape changes may affect the foraging ability of food provisioning parents, as well as reduce the probability a nestling will survive periods of inclement weather, through for example pesticide exposure impairing thermoregulation and punctual anorexia. Breeding in agro-intensive landscapes may thus exacerbate the negative effects of inclement weather under climate change. We used daily temperatures related to significant reductions of insect prey availability (cold snaps), combined with measures of precipitation, and assessed their impact on Tree Swallow (Tachycineta bicolor) fledging success, a declining aerial insectivore breeding across a gradient of agricultural intensification. Fledging success decreased with the number of cold snap days experienced by a brood, and this relationship was worsened during periods of prolonged precipitation. We further found the overall negative effects of experiencing periods of inclement weather are exacerbated in more agro-intensive landscapes. Our results indicate that two of the primary hypothesized drivers of many avian population declines may interact to further increase the rate of declines in certain landscape contexts.

Evidence for multiple drivers of aerial insectivore declines in North America

The Condor ◽  
2019 ◽  
Vol 121 (2) ◽  
Author(s):  
Kimberly J Spiller ◽  
Randy Dettmers
Keyword(s):  
North America ◽  
Habitat Loss ◽  
Prey Abundance ◽  
Research Progress ◽  
Current Evidence ◽  
High Quality ◽  
Prey Quality ◽  
Aerial Insectivore ◽  
Starting Point ◽  
Aerial Insectivores

Abstract Aerial insectivores (birds that forage on aerial insects) have experienced significant population declines in North America. Numerous hypotheses have been proposed for these declines, but current evidence suggests multiple factors could be operating in combination during their annual migratory cycles between breeding and nonbreeding areas. Potential drivers include decreased prey abundance, direct or indirect impacts of environmental contaminants, habitat loss, phenological changes due to warming climate, and conditions on migratory stopover or wintering grounds. While no single threat appears to be the cause of aerial insectivore declines, existing evidence suggests that several of these factors could be contributing to the declines at different times in the annual lifecycle. Breeding productivity for most of these species does not appear to be limited by overall prey abundance, contaminants, or habitat loss, which suggests that similar issues on nonbreeding grounds or carryover effects could play important roles. However, a better understanding of the importance of prey quality throughout the lifecycle is critically needed. Based on current evidence, we propose that changes in availability of high-quality prey, with variability across breeding and nonbreeding grounds, reduce various combinations of fledging success, post-fledging survival, and nonbreeding season body condition of aerial insectivores, resulting in species and geographic differences in population trends. We encourage others to use this hypothesis as a starting point to test specific mechanisms by which availability of high-quality prey influences demographic parameters. We suggest that future research focus on defining prey quality, monitoring insect abundance in conjunction with birds, comparing demographic models across local populations experiencing different population growth rates, and using tracking technology to document important migratory and nonbreeding areas. Considerable research progress already has been made, but additional research is needed to better understand the complex web of potential causes driving aerial insectivore declines.

scholarly journals Conversion efficiency of α-linolenic acid to omega-3 highly unsaturated fatty acids in aerial insectivore chicks

2017 ◽  
Vol 221 (3) ◽  
pp. jeb165373 ◽  
Author(s):  
Cornelia W. Twining ◽  
Peter Lawrence ◽  
David W. Winkler ◽  
Alexander S. Flecker ◽  
J. Thomas Brenna
Keyword(s):  
Fatty Acids ◽  
Linolenic Acid ◽  
Conversion Efficiency ◽  
Unsaturated Fatty Acids ◽  
Omega 3 ◽  
Highly Unsaturated Fatty Acids ◽  
Aerial Insectivore

scholarly journals Population trend status of Ontario’s forest birds

2009 ◽  
Vol 85 (2) ◽  
pp. 184-201 ◽  
Author(s):  
Peter J Blancher ◽  
R. Dean Phoenix ◽  
Debra S Badzinski ◽  
Michael D Cadman ◽  
Tara L Crewe ◽  
...  
Keyword(s):  
Agricultural Landscapes ◽  
Forest Birds ◽  
Population Trend ◽  
Individual Species ◽  
Population Declines ◽  
Breeding Bird ◽  
The North ◽  
Aerial Insectivore ◽  
Monitoring Reliability ◽  
Wide Scale

Recent population trends of Ontario’s forest birds were assessed by integrating results across 8 bird surveys to provide an estimate of trend status for all of Ontario, and for 2 forested regions of Ontario separately. Surveys with mid- and longterm trends were relied on most extensively in this assessment. Comparison of the first and second Breeding Bird Atlases was especially important for estimating trends in northern forests, but overall reliability of status assessments in the north was considered poor due to limited coverage and significant potential for bias. Trends of most forest birds were stable or positive at the Ontario-wide scale, with trends at least as positive as forest birds elsewhere in North America, and showing more positive trends overall than birds of agricultural landscapes. Nevertheless, individual species trends ranged from large declines to large increases, and several forest birds have been added to Species at Risk lists largely because of population declines. There were few differences in trend status among forest birds grouped by habitat association or migratory guild, although all 5 aerial insectivore species have declined. Better monitoring coverage of the boreal will be needed if improved reliability of trends is desired in the near future. Key words: Ontario, forest birds, boreal forest, population trend, bird surveys, monitoring reliability

scholarly journals Correction to: Wind and rain are the primary climate factors driving changing phenology of an aerial insectivore

2017 ◽  
Vol 284 (1857) ◽  
pp. 20171168
Author(s):  
Rachel D. Irons ◽  
April Harding Scurr ◽  
Alexandra P. Rose ◽  
Julie C. Hagelin ◽  
Tricia Blake ◽  
...  
Keyword(s):  
Climate Factors ◽  
Aerial Insectivore

scholarly journals Wind and rain are the primary climate factors driving changing phenology of an aerial insectivore

2017 ◽  
Vol 284 (1853) ◽  
pp. 20170412 ◽  
Author(s):  
Rachel D. Irons ◽  
April Harding Scurr ◽  
Alexandra P. Rose ◽  
Julie C. Hagelin ◽  
Tricia Blake ◽  
...  
Keyword(s):  
Climate Change ◽  
Natural Populations ◽  
Climate Change Impacts ◽  
Tree Swallow ◽  
Breeding Phenology ◽  
Climate Conditions ◽  
Aerial Insectivore ◽  
Windy Weather ◽  
Two Measures

While the ecological effects of climate change have been widely observed, most efforts to document these impacts in terrestrial systems have concentrated on the impacts of temperature. We used tree swallow ( Tachycineta bicolor ) nest observations from two widely separated sites in central Alaska to examine the aspects of climate affecting breeding phenology at the northern extent of this species' range. We found that two measures of breeding phenology, annual lay and hatch dates, are more strongly predicted by windiness and precipitation than by temperature. At our longest-monitored site, breeding phenology has advanced at nearly twice the rate seen in more southern populations, and these changes correspond to long-term declines in windiness. Overall, adverse spring climate conditions known to negatively impact foraging success of swallows (wet, windy weather) appear to influence breeding phenology more than variation in temperature. Separate analyses show that short windy periods significantly delay initiation of individual clutches within years. While past reviews have emphasized that increasing variability in climate conditions may create physiological and ecological challenges for natural populations, we find that long-term reductions in inclement weather corresponded to earlier reproduction in one of our study populations. To better predict climate change impacts, ecologists need to more carefully test effects of multiple climate variables, including some, like windiness, that may be of paramount importance to some species, but have rarely been considered as strong drivers of ecological responses to climate alteration.

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