Partial Incubation and Hatching Asynchrony in the Red-Shouldered Hawk (Buteo lineatus)1

Partial Incubation and Hatching Asynchrony in the Red-Shouldered Hawk (Buteo lineatus)

“…One of these 12 nests experienced partial hatching failure, in which only one of three eggs hatched, so this nest (Adams) was excluded from the calculation of hatching intervals. At the Retswood nest, three eggs of the 4-egg clutch hatched, but the first-laid egg failed to hatch, likely due to exposure to freezing temperatures during which time the egg was not incubated (Miller 2013). Eggs in the other three nests failed to hatch due to depredation of the female parent by a Great Horned Owl (Bubo virginianus) at the Harrison-Grog nest (4 eggs), disturbance from an eastern gray squirrel at the Clough nest (3 eggs), and the unexplained disappearance of the female parent at the Linton nest (3 eggs; see Miller et al 2015 for details).…”

“…In our study, air temperatures may have influenced incubation behavior during egg-laying. The two nests (Paxton and Linton) where hawks approached or achieved full incubation at the beginning of egg-laying experienced isolated events of near-or below-freezing overnight ambient temperatures at the beginning of egg-laying (Miller 2013), which may explain their earlier onset of full incubation (Fig. 2, Supplemental Figure S1).…”

Sibling Aggression, Feeding Rates, and Hatch Rank of Nestling Red-Shouldered Hawks (Buteo lineatus)

“…We visited previously known Red-shouldered Hawk territories (Dykstra et al 2000(Dykstra et al , 2009 from mid-February until the end of March to locate nests and determine occupancy. We considered a nest occupied if it had been improved with fresh sticks or green vegetation (Dykstra et al 2000), and active if there was evidence that eggs had been laid, such as an incubating parent, small down feathers around the edge of the nest, or broken eggshells below the nest (Miller et al 2015(Miller et al , 2020.…”

“…Video Monitoring. In 2011 and 2012, we installed video cameras at selected occupied nests either before eggs were laid or after eggs hatched in active nests (Miller et al 2015(Miller et al , 2020. We selected the camera nests based on the suitability of the tree/nest for a camera placement that allowed a good view of nest contents, safe access for climbers, and permission from landowners; these nests represented a small fraction of the known occupied nests in our study area (generally .100 per year; Dykstra et al 2009Dykstra et al , 2021a.…”

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“…Technological advances in cameras, power sources, and recording/broadcasting devices have greatly enhanced the opportunities for generating detailed, high-quality data linked to Volume 53, Number 1, 2022 parental care while reducing disturbance below the level possible with direct observation of raptors from blinds (Reif and Tornberg 2006). This improved capacity reflects progress from the initial time-lapse camera work of Temple (1972) to the highly effective and more affordable digital video surveillance that is becoming commonplace (e.g., Kross et al 2012, Sonerud et al 2014, Miller et al 2020.…”