Influence of agricultural intensification on prey availability and nestling diet in Tree Swallows (<i>Tachycineta bicolor</i>)

Bellavance, Véronique; Bélisle, Marc; Savage, Jade; Pelletier, Fanie; Garant, Dany

doi:10.1139/cjz-2017-0229

Cited by 33 publications

(75 citation statements)

References 81 publications

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“…The effect of date on nestling viability selection was linear and confirmed that nestlings born later in the season had lower survival. This result is consistent with the finding that early laying is beneficial for female tree swallows (Millet et al 2015), as it increases their nesting success; a relationship also found in several other bird species (Garant et al 2007;Verhulst and Nilsson 2008;Porlier et al 2012) and likely related to a decrease in food availability during the breeding season (Rioux Paquette et al 2013;Bellavance et al 2018). The negative relationship between date and fledging probability could thus be explained by a shortage of food toward the end of the breeding season when food resources are less available while food requirements by nestlings are peaking.…”

Section: Effect Of Sex and Date On Survival And Selectionsupporting

confidence: 89%

“…Previous studies have also reported a positive effect of extensive cultures on nestling survival in our study system (Ghilain and Bélisle 2008;Porlier et al 2009). Weaker selection in extensive cultures could be explained by many factors including a greater availability of insects later in the season in these habitats (Rioux Paquette et al 2013;Bellavance et al 2018). In landscapes dominated by extensive cultures, prey availability generally increases throughout the whole season, while in intensive cultures it increases until mid-June and then decreases quickly in early July (Rioux Paquette et al 2013;Bellavance et al 2018).…”

Section: Land Cover Effects On Survival and Selectionsupporting

confidence: 52%

“…Weaker selection in extensive cultures could be explained by many factors including a greater availability of insects later in the season in these habitats (Rioux Paquette et al 2013;Bellavance et al 2018). In landscapes dominated by extensive cultures, prey availability generally increases throughout the whole season, while in intensive cultures it increases until mid-June and then decreases quickly in early July (Rioux Paquette et al 2013;Bellavance et al 2018). This effect could exacerbate the differences in fledging between areas with different cultures by modulating food access for nestlings at a critical time of their development.…”

Section: Land Cover Effects On Survival and Selectionmentioning

confidence: 99%

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Impacts of environmental heterogeneity on natural selection in a wild bird population*

et al. 2020

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Natural selection has been studied for several decades, resulting in the computation of thousands of selection estimates. Although the importance of environmental conditions on selection has often been suggested, published estimates rarely take into account the effects of environmental heterogeneity on selection patterns. Here, we estimated linear and nonlinear viability selection gradients on morphological traits of 12‐day old nestlings in a wild population of tree swallows (Tachycineta bicolor) across a large‐scale heterogeneous study system in southern Québec, Canada. We assessed the environmental drivers of nestling survival and evaluated their effects on strength and direction of selection gradients. Separate analyses of environmental variables showed that high temperatures and heavy rainfall caused stronger positive linear selection on morphological traits. Weaker linear selection was also measured in more extensively cultivated areas. Both strength and shape of nonlinear quadratic and correlational components of selection were modified by environmental variables. Considering all environmental variables revealed that precipitation since hatching affected patterns of linear selection on traits, while temperatures since hatching shaped nonlinear selection patterns. Our study underlines the importance of quantifying linear and nonlinear natural selection under various environmental conditions and how the evolutionary response of traits may be affected by ongoing human‐induced environmental changes.

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Section: Effect Of Sex and Date On Survival And Selectionsupporting

confidence: 89%

Section: Land Cover Effects On Survival and Selectionsupporting

confidence: 52%

Section: Land Cover Effects On Survival and Selectionmentioning

confidence: 99%

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Impacts of environmental heterogeneity on natural selection in a wild bird population*

et al. 2020

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“…Insect traps were a combined window/water-pan flight trap. Traps were made by bisecting two plexiglass sheets (11.5 cm × 30 cm), and then fixing them on top of a yellow bucket 15 cm deep and 21 cm in diameter (Rioux Paquette et al 2013, Bellavance et al 2018). Traps were then attached to a stake one meter above the ground and filled with approximately one liter of a saltwater and soap solution.…”

Section: Methodsmentioning

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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“…Pesticides have also been implicated in declines in abundance or reproductive success for some other species that were more abundant on organic farms in some provinces (e.g. Song Sparrow in Ontario: Girard, Mineau, & Fahrig, ; Vesper Sparrow: Mineau & Whiteside, ; Tree Swallow: Bellavance, Bélisle, Savage, Pelletier, & Garant, ; Stanton, Morrissey, & Clark, ). Other species favouring organic farms also included species at risk (e.g.…”

Section: Discussionmentioning

confidence: 99%

Organic farming benefits birds most in regions with more intensive agriculture

Kirk¹,

Martin

Lindsay

2020

Journal of Applied Ecology

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Organic farming is considered beneficial for biodiversity conservation in agricultural landscapes but the role of agricultural land use intensity (‘agricultural intensity’), particularly at regional scales, has often been neglected. We used breeding season bird abundance estimates from paired organic‐conventional fields in Saskatchewan (31 pairs), Ontario (36) and Québec (15), Canada to test two alternative predictions: that the positive effect of organic farming on bird abundance was (a) smaller when controlling for overall effects of local‐ and landscape‐scale agricultural intensity (accounting for main effects on abundance); or (b) increases with local‐ or landscape‐scale agricultural intensity (an interaction effect of intensity × organic farming). We also evaluated whether positive effects of organic farming were stronger in regions with greater agricultural intensity. The effect of organic farming on the cross‐species abundance of birds was only statistically supported in Ontario when not accounting for agricultural intensity. However, the estimated effect of organic farming was the same whether or not we controlled for agricultural intensity in Saskatchewan (supported positive effect) and Québec (unsupported effect). Little support existed for more positive effects of organic farming on abundance in areas with greater local‐ or landscape‐scale agricultural intensity. In Ontario, there was a trend for more positive effects of organic farming in more intensively farmed landscapes. Our results showed, for the first time in North America, an effect of regional‐scale agricultural intensity on the potential benefit of organic farms. The influence of organic farming on abundance was most positive in the region with the most intensive agriculture (Saskatchewan) and least positive in the region with the least intensive agriculture (Québec). Additionally, we showed that benefits of organic farming can be overestimated if the effects of local‐ and landscape‐scale agricultural intensity are not considered. However, positive effects of organic farming on cross‐species abundance and the abundance of individual species were still detectable when we controlled for agricultural intensity at local‐ and landscape‐scales. Synthesis and applications. When evaluating impacts of organic farming on biodiversity, it is important to consider the intensity of surrounding agricultural practices at local to regional scales. Our cross‐regional comparison showed that organic farming had the most positive effect on abundance of birds in the region with the most intensive agriculture (Saskatchewan) and least positive effect in the region with the least intensive agriculture (Québec). This demonstrates that birds can benefit from organic farming and this effect can be most pronounced in regions with more intensive agriculture, implying that birds may benefit most from expansion of the area of organic farming in regions where farming is most intensive.

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Influence of agricultural intensification on prey availability and nestling diet in Tree Swallows (Tachycineta bicolor)

Cited by 33 publications

References 81 publications

Impacts of environmental heterogeneity on natural selection in a wild bird population*

Impacts of environmental heterogeneity on natural selection in a wild bird population*

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

Organic farming benefits birds most in regions with more intensive agriculture

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