Birds advancing lay dates with warming springs face greater risk of chick mortality

In response to a warming planet with earlier springs, migratory animals are adjusting the timing of essential life stages. Although these adjustments may be essential for keeping pace with resource phenology, they may prove insufficient, as evidenced by population declines in many species. However, even when species can match the tempo of climate change, other consequences may emerge when exposed to novel conditions earlier in the year. Here, using three long-term datasets on bird reproduction, daily insect availability, and weather, we investigated the complex mechanisms affecting reproductive success in an aerial insectivore, the tree swallow (Tachycineta bicolor). By examining breeding records over nearly half a century, we discovered that tree swallows have continuously advanced their egg laying by ∼3 d per decade. However, earlier-hatching offspring are now exposed to inclement weather events twice as often as they were in the 1970s. Our long-term daily insect biomass dataset shows no long-term trends over 25 y but precipitous drops in flying insect numbers on days with low ambient temperatures. Insect availability has a considerable impact on chick survival: Even a single inclement weather event can reduce offspring survival by >50%. Our results highlight the multifaceted threats that climate change poses on migrating species. The decoupling between cold snap occurrence and generally warming spring temperatures can affect reproductive success and threaten long-term persistence of populations. Understanding the exact mechanisms that endanger aerial insectivores is especially timely because this guild is experiencing the steepest and most widespread declines across North America and Europe.

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

10.1101/2021.06.29.450344 ◽

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.

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Interactive influences of fluctuations of main food resources and climate change on long-term population decline of Tengmalm’s owls in the boreal forest

Scientific Reports ◽

10.1038/s41598-020-77531-y ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Marek Kouba ◽

Luděk Bartoš ◽

Jitka Bartošová ◽

Kari Hongisto ◽

Erkki Korpimäki

Keyword(s):

Climate Change ◽

Reproductive Success ◽

Population Decline ◽

Egg Laying ◽

Laying Date ◽

Late Winter ◽

Aegolius Funereus ◽

Increasing Temperature ◽

Tengmalm's Owl

AbstractRecent wildlife population declines are usually attributed to multiple sources such as global climate change and habitat loss and degradation inducing decreased food supply. However, interactive effects of fluctuations in abundance of main foods and weather conditions on population densities and reproductive success have been studied rarely. We analysed long-term (1973–2018) data on Tengmalm’s owl (Aegolius funereus) and the influence of prey abundance and weather on breeding densities and reproductive success in western Finland. We found that fledgling production per breeding attempt declined and laying date of the owl population delayed during the period between 1973 and 2018. The breeding density of the owl population decreased with increasing temperature in winter (October–March), fledgling production increased with increasing temperature and precipitation in spring (April–June), whereas the initiation of egg-laying was delayed with increasing depth of snow cover in late winter (January–March). The decreasing trend of fledgling production, which was mainly due to starvation of offspring, was an important factor contributing to the long-term decline of the Tengmalm’s owl study population. Milder and more humid spring and early summer temperatures due to global warming were not able to compensate for lowered offspring production of owls. The main reason for low productivity is probably loss and degradation of mature and old-growth forests due to clear-felling which results in loss of coverage of prime habitat for main (bank voles) and alternative foods (small birds) of owls inducing lack of food, and refuges against predators of Tengmalm’s owls. This interpretation was also supported by the delayed start of egg-laying during the study period although ambient temperatures increased prior to and during the egg-laying period.

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Endogenous biomarkers reveal diet partitioning among three sympatric species of swallows

The Auk ◽

10.1093/ornithology/ukab078 ◽

2021 ◽

Cited By ~ 1

Author(s):

Kaelyn H Bumelis ◽

Michael D Cadman ◽

Keith A Hobson

Keyword(s):

Isotope Analysis ◽

Sympatric Species ◽

Tree Swallow ◽

Population Declines ◽

Interspecific Differences ◽

Cliff Swallow ◽

Aerial Insectivores ◽

Breeding Grounds ◽

Potential Factors ◽

Δ 15N

Abstract Since the early 1990s, aerial insectivorous birds have shown serious population declines in North America, but it is not clear if factors common to all species within this guild account for these declines. Among sympatric swallows, population trends differ, and this may be due to differences in ecology operating throughout the annual cycle. Although these species all feed on aerial insects, prey taxa can differ tremendously in their “aeroecology” and use by swallows. We examined the potential for dietary differences among three species of swallows, Barn Swallow (Hirundo rustica), Cliff Swallow (Petrochelidon pyrrhonota), and Tree Swallow (Tachycineta bicolor), breeding sympatrically in southern Ontario, Canada. Potential interspecific differences in nestling diet were examined using two endogenous biomarkers, DNA barcoding of nestling feces and stable isotope analysis (δ 2H, δ 13C, δ 15N) of nestling feathers. We found evidence for differences in dietary sources of provisioned young where Barn Swallows provisioned more terrestrial-based prey, Cliff Swallows provisioned an intermediate diet, and Tree Swallows the most aquatic-emergent insect diet. We suggest this information may help to identify potential factors contributing to differential declines of aerial insectivores operating on the breeding grounds, including diet quality.

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Costs of Egg Punctures and Parasitism by Shiny Cowbirds (Molothrus Bonariensis) at Creamy-Bellied Thrush (Turdus Amaurochalinus) Nests

The Auk ◽

10.1093/auk/123.1.23 ◽

2006 ◽

Vol 123 (1) ◽

pp. 23-32 ◽

Cited By ~ 3

Author(s):

Andrea A. Astié ◽

Juan C. Reboreda

Keyword(s):

Reproductive Success ◽

Hatching Success ◽

Nest Survival ◽

Egg Laying ◽

Chick Survival ◽

Egg Survival ◽

Lower Survival Rate ◽

Molothrus Bonariensis ◽

Primary Determinant ◽

The Cost

AbstractMost studies on cowbird parasitism have focused on its effects on parasitized nests, whereas few have considered the costs at nests that cowbirds visit but at which they do not lay eggs. Shiny Cowbirds (Molothrus bonariensis) peck and puncture host eggs both in nests where they lay eggs and in unparasitized nests. We analyzed the effect of egg punctures in unparasitized and parasitized nests of a large host, the Creamy-bellied Thrush (Turdus amaurochalinus; hereafter “thrush”), as well as the costs of Shiny Cowbird eggs and chicks in this host’s nests. We determined thrush egg survival, hatching success, and chick survival in successful nests, and nest survival during the egg and nestling stages. Frequency of parasitism was 60%, and its intensity 1.6 ± 0.1 eggs nest−1. Number of host eggs punctured was positively associated with intensity of parasitism. The host’s eggs were frequently punctured in parasitized nests (71%) and in unparasitized nests (42%). Egg punctures reduced the number of eggs at hatching in 23% and 49% of unparasitized and parasitized nests, respectively. Nests with egg punctures had a lower survival rate than nests without them, but nest survival was not associated with parasitism. Presence of a Shiny Cowbird egg was associated with a decrease in the hatching success of host eggs, but presence of a Shiny Cowbird chick did not have any detrimental effect on either the survival and growth rate of host chicks in successful nests or the survival of the whole nest. Our results show that egg punctures were the primary determinant of thrush reproductive success. Consequently, comparison of unparasitized and parasitized nests gives an incomplete estimation of the effects of Shiny Cowbirds on host reproductive success, because the cost of egg punctures is also important in nests where there is no Shiny Cowbird egg laying.Costos de la Perforación de Huevos y el Parasitismo por Molothrus bonariensis en Nidos de Turdus amaurochalinus

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Cryptic and cumulative impacts on the wintering habitat of the endangered black-faced spoonbill (Platalea minor) risk its long-term viability

Environmental Conservation ◽

10.1017/s0376892917000340 ◽

2017 ◽

Vol 45 (2) ◽

pp. 147-154 ◽

Cited By ~ 2

Author(s):

EVAN J. PICKETT ◽

MELANIE CHAN ◽

WENDA CHENG ◽

JOHN ALLCOCK ◽

SIMBA CHAN ◽

...

Keyword(s):

Climate Change ◽

Habitat Loss ◽

Population Change ◽

Anthropogenic Impacts ◽

Population Viability Analysis ◽

Cumulative Impacts ◽

Population Declines ◽

Distribution Models ◽

Waterbird Species

SUMMARYThe East Asian–Australasian flyway contains some of the most threatened habitats in the world, with at least 155 waterbird species reliant on the tidal habitats it comprises. The black-faced spoonbill (Platalea minor) is an iconic endangered species distributed across the coast of East Asia. Its population suffered a severe decline into the 1990s, but extensive monitoring and conservation interventions have aided a substantial recovery of the species. We used a population viability analysis based on data collected over the past two decades in conjunction with species distribution models to project spatially explicit models of population change for the next 35 years. Over nearly all scenarios of habitat loss and climate change, the global spoonbill population was projected to increase in the short-term due to low population numbers likely well below current population carrying capacities. However, climate change and habitat loss together threaten the recovery of the spoonbill population such that, by 2050, population declines are apparent as a consequence of these cumulative impacts. These threats are also cryptic and represent a challenge to the conservation of species recovering from anthropogenic impacts; observed population increases can hide large reductions in habitat suitability that threaten the long-term viability of species.

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

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2017.0412 ◽

2017 ◽

Vol 284 (1853) ◽

pp. 20170412 ◽

Cited By ~ 10

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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Divorce and breeding dispersal in the dunlin Calidris alpina: support for the better option hypothesis?

Behaviour ◽

10.1163/156853912x626295 ◽

2012 ◽

Vol 149 (1) ◽

pp. 67-80 ◽

Cited By ~ 9

Author(s):

Donald Blomqvist ◽

Lars-Åke Flodin

Keyword(s):

Reproductive Success ◽

Egg Laying ◽

Male Reproductive Success ◽

Breeding Dispersal ◽

Social Monogamy ◽

Calidris Alpina ◽

Pair Bonds ◽

Mate Change ◽

Term Data

AbstractSocial monogamy is a rare mating system among animals, occurring commonly only in birds. In long-lived birds, pair bonds may persist for several seasons in some species, while in others mate change occurs even when both partners are still alive. Here, we test predictions from the adaptive hypotheses for divorce, using long-term data (15 years) on mate change and reproductive success in a long-lived shorebird, the dunlin Calidris alpina. We found that about one quarter of the pairs divorced (23% of 126 breeding attempts). Among the divorcing females, six changed partner more than once (one female changed partner three times). Following divorce, females dispersed longer than males. Start of egg-laying (presumably reflecting arrival time to the breeding ground), previous breeding success, and male age or size did not seem to influence the occurrence of divorce. However, females that changed mate between consecutive breeding attempts achieved higher reproductive success. Moreover, this improvement appeared independent of breeding experience. Since we were unable to detect any effect of divorce on male reproductive success, our results suggest that divorce in the dunlin is best explained by the better option hypothesis.

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Climate change and the demographic demise of a hoarding bird living on the edge

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2006.3667 ◽

2006 ◽

Vol 273 (1603) ◽

pp. 2809-2813 ◽

Cited By ~ 45

Author(s):

Thomas A Waite ◽

Dan Strickland

Keyword(s):

Climate Change ◽

Reproductive Success ◽

Cold Storage ◽

Migratory Bird ◽

Lower Latitude ◽

Subalpine Forest ◽

Population Declines ◽

Perisoreus Canadensis ◽

Local Extinctions ◽

Study Population

Population declines along the lower-latitude edge of a species' range may be diagnostic of climate change. We report evidence that climate change has contributed to deteriorating reproductive success in a rapidly declining population of the grey jay ( Perisoreus canadensis ) at the southern edge of its range. This non-migratory bird of boreal and subalpine forest lives on permanent territories, where it hoards enormous amounts of food for winter and then breeds very early, under still-wintry conditions. We hypothesized that warmer autumns have increased the perishability of hoards and compromised subsequent breeding attempts. Our analysis confirmed that warm autumns, especially when followed by cold late winters, have led to delayed breeding and reduced reproductive success. Our findings uniquely show that weather months before the breeding season impact the timing and success of breeding. Warm autumns apparently represent hostile conditions for this species, because it relies on cold storage. Our study population may be especially vulnerable, because it is situated at the southern edge of the range, where the potential for hoard rot is most pronounced. This population's demise may signal a climate-driven range contraction through local extinctions along the trailing edge.

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Microclimate and resource quality determine resource use in a range-expanding herbivore

Biology Letters ◽

10.1098/rsbl.2021.0175 ◽

2021 ◽

Vol 17 (8) ◽

pp. 20210175

Author(s):

James E. Stewart ◽

Ilya M. D. Maclean ◽

Alice J. Edney ◽

Jon Bridle ◽

Robert J. Wilson

Keyword(s):

Climate Change ◽

Spatial Scales ◽

Good Condition ◽

Biotic Interactions ◽

Egg Laying ◽

Emergent Properties ◽

Ecological Communities ◽

Ambient Temperatures ◽

Resource Condition ◽

Range Dynamics

The consequences of climate change for biogeographic range dynamics depend on the spatial scales at which climate influences focal species directly and indirectly via biotic interactions. An overlooked question concerns the extent to which microclimates modify specialist biotic interactions, with emergent properties for communities and range dynamics. Here, we use an in-field experiment to assess egg-laying behaviour of a range-expanding herbivore across a range of natural microclimatic conditions. We show that variation in microclimate, resource condition and individual fecundity can generate differences in egg-laying rates of almost two orders of magnitude in an exemplar species, the brown argus butterfly ( Aricia agestis ). This within-site variation in fecundity dwarfs variation resulting from differences in average ambient temperatures among populations. Although higher temperatures did not reduce female selection for host plants in good condition, the thermal sensitivities of egg-laying behaviours have the potential to accelerate climate-driven range expansion by increasing egg-laying encounters with novel hosts in increasingly suitable microclimates. Understanding the sensitivity of specialist biotic interactions to microclimatic variation is, therefore, critical to predict the outcomes of climate change across species' geographical ranges, and the resilience of ecological communities.

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Insects and recent climate change

10.1101/2020.03.09.984328 ◽

2020 ◽

Cited By ~ 1

Author(s):

Christopher A. Halsch ◽

Arthur M. Shapiro ◽

James A. Fordyce ◽

Chris C. Nice ◽

James H. Thorne ◽

...

Keyword(s):

Climate Change ◽

Empirical Work ◽

Climate Change Impacts ◽

Natural World ◽

High Elevation ◽

Population Declines ◽

Climatic Fluctuations ◽

Recent Climate Change ◽

Recent Climate

AbstractInsects have diversified through 400 million years of Earth’s changeable climate, yet recent and ongoing shifts in patterns of temperature and precipitation pose novel challenges as they combine with decades of other anthropogenic stressors including the conversion and degradation of land. Here we consider how insects are responding to recent climate change, while summarizing the literature on long-term monitoring of insect populations in the context of climatic fluctuations. Results to date suggest that climate change impacts on insects have the potential to be considerable, even when compared to changes in land use. The importance of climate is illustrated with a case study from the butterflies of Northern California, where we find that population declines have been severe in high-elevation areas removed from the most immediate effects of habitat loss. These results shed light on the complexity of montane-adapted insects responding to changing abiotic conditions and raise questions about the utility of temperate mountains as refugia during the Anthropocene. We consider methodological issues that would improve syntheses of results across long-term insect datasets and highlight directions for future empirical work.Significance statementAnthropogenic climate change poses multiple threats to society and biodiversity, and challenges our understanding of the resilience of the natural world. We discuss recent ideas and evidence on this issue and conclude that the impacts of climate change on insects in particular have the potential to be more severe than might have been expected a decade ago. Finally, we suggest practical measures that include the protection of diverse portfolios of species, not just those inhabiting what are currently the most pristine areas.

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