Habitat and weather conditions influence reproductive rates of suburban and rural Red‐shouldered Hawks Buteo lineatus

Abstract

Both habitat and weather can strongly influence reproductive rates of birds. We measured reproductive rates of suburban and rural Red‐shouldered Hawks Buteo lineatus in southern Ohio, USA, from 1997 to 2016, and then tested how weather conditions and habitat in the areas surrounding the nest‐sites were related to two measures of reproductive rate. Reproductive rates of Red‐shouldered Hawks did not differ between the suburban and rural study areas, and were relatively stable from year to year. Suburban Red‐shouldered Hawks produced 2736 young in 1773 nesting attempts (i.e. nest with eggs) at 302 territories (1.54 young per nesting attempt), and rural‐nesting Hawks produced 996 young in 640 nesting attempts at 108 territories (1.56 young per nesting attempt). Annual nesting success averaged 58.9 ± 1.1% for suburban birds and 58.9 ± 2.1% for rural birds. Several factors influenced Red‐shouldered Hawk reproductive rates, measured as either the number of young per nesting attempt or the percentage of nesting attempts that were successful. Higher air temperatures during May (the nestling period) and increasing amounts of coniferous forest were associated with higher reproductive rates, whereas increasing April air temperatures and increasing amount of grassland cover had the opposite effect. Land cover variables associated with suburban landscapes, such as the amount of residential development, did not influence the number of young per nesting attempt or nesting success, suggesting that Red‐shouldered Hawks are welladapted to human‐dominated landscapes in southern Ohio. Our study also illustrates the value of long‐term datasets for improving our understanding of factors that affect raptors’ demographic parameters.

Breeding Phenology of Red-Shouldered Hawks (Buteo lineatus) Is Related to Snow Cover and Air Temperature During the Pre-Laying Period

“…Likewise, the variation in mean March temperature was moderate, ranging from -0.2 o C to 7.7 o C, although the variation in the number of days with snow cover was somewhat larger, ranging from 0 to 23 (total for February and March together; Figure 1). Our study areas in southern Ohio occupy the center of the eastern range of the species and reproductive rates here are mid-range to high (Dykstra et al, 2020), with relatively little year-to-year variation (Dykstra et al, 2021). Though climate change is occurring here (Frankson et al, 2017), our results indicated that effects were not detectable in February-March over the time period of 1997 to 2020, though temperatures in April and May did increase during that period in our study area (Dykstra et al, 2021).…”

“…Our study areas in southern Ohio occupy the center of the eastern range of the species and reproductive rates here are mid-range to high (Dykstra et al, 2020), with relatively little year-to-year variation (Dykstra et al, 2021). Though climate change is occurring here (Frankson et al, 2017), our results indicated that effects were not detectable in February-March over the time period of 1997 to 2020, though temperatures in April and May did increase during that period in our study area (Dykstra et al, 2021). Despite the fairly modest amount of variation, we documented significant influence of snow cover and air temperature on breeding phenology in a long-term study.…”

“…Investigation of breeding phenology requires a long-term dataset, such as exists for Red-shouldered Hawks (Buteo lineatus) nesting in southern Ohio (Dykstra et al, 2019(Dykstra et al, , 2021. A dietary generalist, the Red-shouldered Hawk inhabits forested areas (e.g., Titus and Mosher, 1981;Bosakowski et al, 1992;Bosakowski and Smith, 1997) and urban/suburban landscapes (Bloom and McCrary, 1996;Dykstra et al, 2000Dykstra et al, , 2018Dykstra et al, , 2021 in the eastern half of North America, with a separate subspecies in the far west (Dykstra et al, 2020). In southern Ohio, where, the species is resident year round and has been studied since 1997, birds nesting in urban/suburban areas have reproductive rates equal to those in a nearby natural forested region (Dykstra et al, 2009(Dykstra et al, , 2021.…”

“…A dietary generalist, the Red-shouldered Hawk inhabits forested areas (e.g., Titus and Mosher, 1981;Bosakowski et al, 1992;Bosakowski and Smith, 1997) and urban/suburban landscapes (Bloom and McCrary, 1996;Dykstra et al, 2000Dykstra et al, , 2018Dykstra et al, , 2021 in the eastern half of North America, with a separate subspecies in the far west (Dykstra et al, 2020). In southern Ohio, where, the species is resident year round and has been studied since 1997, birds nesting in urban/suburban areas have reproductive rates equal to those in a nearby natural forested region (Dykstra et al, 2009(Dykstra et al, , 2021. Weather influences reproductive output in both populations: warmer mean temperatures in May (the nestling-rearing period) are associated with higher productivity (young per nesting attempt) and greater nesting success (Dykstra et al, 2021).…”

“…In southern Ohio, where, the species is resident year round and has been studied since 1997, birds nesting in urban/suburban areas have reproductive rates equal to those in a nearby natural forested region (Dykstra et al, 2009(Dykstra et al, , 2021. Weather influences reproductive output in both populations: warmer mean temperatures in May (the nestling-rearing period) are associated with higher productivity (young per nesting attempt) and greater nesting success (Dykstra et al, 2021).…”