Agricultural land cover does not affect the diet of Tree Swallows in wetland-dominated habitats

Michelson, Chantel I.; Clark, Robert G.; Morrissey, Christy A.

doi:10.1650/condor-18-16.1

Cited by 31 publications

(20 citation statements)

References 47 publications

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“…Variation in landscape contexts may also have resulted in Tree swallows feeding on diets differing not in prey species composition, but also in nutritive value. Indeed, the diet of Tree swallows varies across the agricultural intensification gradient covered by our study area (Bellavance et al 2018; see also (Nocera et al 2012, Michelson et al 2018)). In the period during which Tree swallows provide food to nestlings, they eat more Diptera and less Ephemeroptera in landscapes dominated by row crops than in landscapes mostly devoted to forage crops and pastures (Bellavance et al 2018).…”

Section: Discussionmentioning

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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Section: Discussionmentioning

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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“…Between May and July of 2017 and 2018, we visited wetlands at 5 sites, 2 dominated by grassland (including tamed pasture) and 3 dominated by agriculture (cropland), near Saskatoon, Saskatchewan, Canada. These sites were chosen because of their accessibility and historical use by other researchers (Stanton et al ; Michelson et al ) and are named as follows: Allan, Saskatchewan, Canada (grassland, 51.6260 N, –105.9717 W); St. Denis National Wildlife Area (grassland, 52.2153 N, –106.0770 W); Burr, Saskatchewan, Canada (cropland, 51.9809 N, –105.0774 W); Colonsay, Saskatchewan, Canada (cropland, 52.0264 N, –105.9217 W); and Humboldt, Saskatchewan, Canada (cropland, 52.1993 N, –105.2883 W). At Humboldt, approximately half of the site was acquired by Ducks Unlimited in 2016 and has undergone some habitat restoration (R. Clark, Environment and Climate Change Canada, Saskatoon, Saskatchewan, Canada, personal communication).…”

Section: Methodsmentioning

confidence: 99%

Section: Study Area and Sample Collectionmentioning

confidence: 99%

Detecting Amphibians in Agricultural Landscapes Using Environmental DNA Reveals the Importance of Wetland Condition

Ruso

Morrissey

Hogan

et al. 2019

Enviro Toxic and Chemistry

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Amphibians are declining worldwide, in part because of large‐scale degradation of habitat from agriculture and pervasive pathogens. Yet a common North American amphibian, the wood frog (Lithobates sylvaticus), ranges widely and persists in agricultural landscapes. Conventional survey techniques rely on visual encounters and dip‐netting efforts, but detectability limits the ability to test for the effects of environmental variables on amphibian habitat suitability. We used environmental DNA to determine the presence of wood frogs and an amphibian pathogen (ranavirus) in Prairie Pothole wetlands and investigated the effects of 32 water quality, wetland habitat, and landscape‐level variables on frog presence at sites representing different degrees of agricultural intensity. Several wetland variables influenced wood frog presence, the most influential being those associated with wetland productivity (i.e., nutrients), vegetation buffer width, and proportion of the surrounding landscape that is comprised of other water bodies. Wood frog presence was positively associated with higher dissolved phosphorus (>0.4 mg/L), moderate dissolved nitrogen (0.1–0.2 mg/L), lower chlorophyll a (≤15 µg/L), wider vegetation buffers (≥10 m), and more water on the landscape (≥0.25). These results highlight the effects of environmental factors at multiple scales on the presence of amphibians in this highly modified landscape—namely the importance of maintaining wetland water quality, vegetation buffers, and surrounding habitat heterogeneity. Environ Toxicol Chem 2019;38:2750–2763. © 2019 SETAC

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“…Imlay et al (2017) found that low insect abundance was not related to a decrease in nestling survival and mass, as adults are able to increase their foraging efforts. Using isotopic analysis, Michelson et al (2018) found high diversity and annual variation in the nestling Tree Swallow diet, but insects from aquatic orders were consumed in greater proportion than insects from terrestrial orders. Our study is unable to determine if aquatic insects were included in the diet in larger proportions during earlier stages of nestling development, which would require the collection of boluses.…”

Section: Discussionmentioning

confidence: 99%

Tree Swallow (Tachycineta bicolor) nest success and nestling growth near oil sands mining operations in northeastern Alberta, Canada

2019

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Industrial development and contaminant exposure may affect reproductive success and food quality for birds. Tree Swallows (Tachycineta bicolor (Vieillot, 1808)) nesting near oil sands development in northern Alberta (Canada) potentially experience elevated environmental stressors that could influence reproduction. We measured reproductive and growth endpoints in Tree Swallows, predicting reduced reproductive success and nestling growth near oil sands operations compared with reference sites. We also identified the invertebrate prey in the stomach contents of nestlings to understand variability in the diet and its potential effect on growth and survival of nestlings. From 2012 to 2015, clutch initiation varied among years but was not influenced by proximity to oil sands operations. Hatching and fledging success decreased in response to increased precipitation, regardless of location. Measurements of nestling growth reflected the variation associated with nestling sex and possibly asynchronous hatching. The composition of the nestling diet was significantly different; birds near oil sands development consumed Odonata, whereas birds at reference sites consumed Ephemeroptera. Nestlings from all sites consumed relatively high quantities of terrestrial insects. Our results demonstrate that factors such as weather conditions, diet, hatching order, and nestling sex are important when interpreting the potential effects of oil sands development on nest success and nestling growth.

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Agricultural land cover does not affect the diet of Tree Swallows in wetland-dominated habitats

Cited by 31 publications

References 47 publications

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

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

Detecting Amphibians in Agricultural Landscapes Using Environmental DNA Reveals the Importance of Wetland Condition

Tree Swallow (Tachycineta bicolor) nest success and nestling growth near oil sands mining operations in northeastern Alberta, Canada

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