![]() ![]() We used Program MARK to evaluate the influence of land cover on nest success. During 2014, 7 of 10 active nests fledged 22 chicks (3.1 chicks/successful nest) overall, 29 (2.9 chicks/successful nest) nestlings fledged in our study area. During the 2013 breeding season, 3 of 12 active nests fledged 7 chicks (2.3 chicks/successful nest). Apparent nest success was 25% in 2013, and 70% in 2014. n = 3), and residual corn ( Zea mays n = 1). Most northern harrier nests were in seasonal or permanent wetlands with cordgrass ( Spartina spp n = 12), bulrush ( Scirpus spp. During breeding seasons in 20, one breeding pair of northern harrier was found every 370.6 km 2. No golden eagle nest was documented in ED. Cottonwood ( Populus deltoides) was the sole tree of choice for nesting golden eagles in WD (n = 30) followed by steep cliff-side (n = 5). Overall, 41 golden eagle chicks successfully fledged 1.4 chicks/successful nest (SE = 0.09). Active nests of golden eagles were placed on two different substrates (i.e., steep cliff-side and trees ) and apparent nest success was 62% in 2013, 94% in 2014, and 87% in 2015. In WD golden eagle pairs were documented with one nest every 1740.4 km 2 for the duration of the study. Overall, 101 ferruginous hawk chicks fledged in ED 2.4 fledglings/successful nest, and 100 chicks fledged in WD 2.6 fledglings/successful nest. In ED, all ferruginous hawk nests were in trees, and apparent nest success was 62% in 2013, 94% in 2014, and 87% in 2015. In WD, we documented one breeding pair in 315 km 2. In a more suitable subset of 4420 km 2 in ED, we found one pair per 340 km 2. In ED, one pair of ferruginous hawk was found every 655 km 2. Using ground and aerial surveys, we located and monitored active ferruginous hawk, golden eagle, and northern harrier nests (ferruginous hawk, n = 55 golden eagle. During the breeding season from 2013–2015, we investigated the influence of factors associated with the landscape on survival and nest-site selection of ferruginous hawks, golden eagles, and northern harriers in the northern Great Plains (north-central South Dakota, south-central North Dakota hereafter, Eastern Dakota, and northwestern South Dakota hereafter, Western Dakota ). Northern harriers ( Circus cyaneus) prefer relatively open grasslands and wetland areas of various natures. Population trends of golden eagles in western United States are unclear although long-term monitoring of populations shows declines in occupancy and breeding performance. Golden eagles ( Aquila chrysaetos) are long-lived raptors with high nest-site fidelity and relatively low reproductive success. Their population reportedly declines in number if more than 30% of an area is cultivated and they rarely nest in areas dominated by croplands. Ferruginous hawks ( Buteo regalis) are a grassland and shrubland obligate nesting raptor and prefer lightly grazed pasture or idle areas for nesting.
0 Comments
Leave a Reply. |