B. J. McCaffery | Geology Reports

USGS2010

Detection probability of cliff-nesting raptors during helicopter and fixed-wing aircraft surveys in western Alaska

We conducted repeated aerial surveys for breeding cliff-nesting raptors on the Yukon Delta National Wildlife Refuge (YDNWR) in western Alaska to estimate detection probabilities of Gyrfalcons (Falco rusticolus), Golden Eagles (Aquila chrysaetos), Rough-legged Hawks (Buteo lagopus), and also Common Ravens (Corvus corax). Using the program PRESENCE, we modeled detection histories of each species based on single species occupancy modeling. We used different observers during four helicopter replicate surveys in the Kilbuck Mountains and five fixed-wing replicate surveys in the Ingakslugwat Hills near Bethel, AK. During helicopter surveys, Gyrfalcons had the highest detection probability estimate (p^;p^ 0.79; SE 0.05), followed by Golden Eagles (p^=0.68; SE 0.05), Common Ravens (p^=0.45; SE 0.17), and Rough-legged Hawks (p^=0.10; SE 0.11). Detection probabilities from fixed-wing aircraft in the Ingakslugwat Hills were similar to those from the helicopter in the Kilbuck Mountains for Gyrfalcons and Golden Eagles, but were higher for Common Ravens (p^=0.85; SE 0.06) and Rough-legged Hawks (p^=0.42; SE 0.07). Fixed-wing aircraft provided detection probability estimates and SEs in the Ingakslugwat Hills similar to or better than those from helicopter surveys in the Kilbucks and should be considered for future cliff-nesting raptor surveys where safe, low-altitude flight is possible. Overall, detection probability varied by observer experience and in some cases, by study area/aircraft type.

Alaska↗

USGS2009

Behavior and reproductive success of rock sandpipers breeding on the Yukon-Kuskokwim river delta, Alaska

We studied Rock Sandpiper ( Calidris ptilocnemis ) breeding behavior and monitored reproductive success from 1998 to 2005 on the Yukon-Kuskokwim River Delta, Alaska, USA. We banded 24 adults and monitored 45 nests. Annual return rate of adults ranged between 67 and 100%. Six pairs of Rock Sandpipers bred at our study site for ≥2 years, and among these we did not observe mate change (i.e., when both members of a pair returned and each mated with a new individual). Nests were typically initiated by mid-May and 53% of females laid second clutches if first clutches were lost through mid-June. Males regularly incubated clutches during the morning (0800–1259 hrs AKDT) and afternoon (1300–1759 hrs) and rarely during the evening (1800– 2300 hrs), whereas female incubation was relatively consistent throughout the day. Apparent nest success (percent of known nests successfully hatching >1 chick) among first and second nests was 19 and 44%, respectively ( n = 45). A minimum of 44% of hatching nests fledged at least one young. Males cared for young but half of females deserted mate and brood 1–7 days post-hatch. This first description of North American Rock Sandpiper breeding behavior from a color-marked population complements previous work on this species on the Chukotsky Peninsula, Russia.

Wilson Journal of Ornithology↗