The Peregrine Falcon (Falco peregrinus) became extirpated during the 1960s, while the Prairie Falcon (Falco mexicanus) increased on a sympatric nesting range along a section of river in Alberta, Canada. Following the release of 233 captive-reared juvenile peregrines in 1992–96, some peregrines returned to the river to breed, reaching a high of seven pairs in 2000, but declining again to two pairs in 2006. In an inverse relationship, the number of Prairie Falcon nests dropped from five to two and then went back up to four. We hypothesize that the peregrine's failure to reach former densities in the study area was due to habitat deterioration which resulted in a reduced prey base compared to pre-1960s conditions. Interspecific strife with Prairie Falcons was common at contested nest sites. The Peregrine Falcons were the dominant aggressors, replacing pairs of Prairie Falcons at some, but not all, historical cliff eyries.

I studied breeding habitat selection by sympatric Grey-faced Buzzards (Butastur indicus) and Northern Goshawks (Accipiter gentilis) at local (0.1 ha circles) and landscape (1017 ha circles) scales in Zuojia Nature Reserve, Jinlin province, China from 1995–1999. Compared to paired random plots, Grey-faced Buzzards selected nest sites with dense shrubs and steep slopes with a northerly slope aspect. They nested in sites with fewer open areas that were relatively far from the nearest forest edge and nearest disturbance, compared to random plots. Northern Goshawks selected nest sites with taller trees and denser shrubs than those in the random plots. Goshawk nest sites also were relatively far from the nearest forest edge and the nearest disturbance, compared to random plots. Comparing nests of Grey-faced Buzzards to those of Northern Goshawks, I found that most nest sites of the Grey-faced Buzzards were located on the upper third of the slope while most Northern Goshawk nest sites were on the lower portion of the slope. Grey-faced Buzzards were associated with smaller nest trees on steeper slopes than were Northern Goshawks. Buzzard nest landscape-scale plots had larger forest patch size, smaller amounts of open areas, greater distance to the nearest forest edges, and less human disturbance, compared to Northern Goshawk plots.

Swainson's Hawks (Buteo swainsoni) are listed as state-endangered in Illinois but virtually nothing is known about the small population persisting in the northeastern corner of the state. This population is separated from the nearest western populations by about 355 km. We estimated the size of the Illinois population at 10–16 adults in 2003 and conducted a preliminary study of the genetic relationship between the Illinois population and birds from Idaho near the western edge of their geographic range. We found slight but significant differentiation between the two populations. Band-sharing was high within (80–85%) and between (81%) populations suggesting fairly recent (within 150 yrs) isolation of the Illinois population.

The regional population of the Grey-headed Fish-Eagle (Ichthyophaga ichthyaetus) in Southeast Asia is thought to be in recent decline and its conservation status under threat. We undertook a systematic survey in a flooded swamp forest at the Tonle Sap Lake in Cambodia and recorded 32 pairs of eagles in an area of approximately 80 km². Three species of water snakes were identified as eagle prey items, previously unrecorded for this species. We suggest that this eagle population has significant regional importance and discuss potential anthropogenic threats to population stability, such as water snake harvesting and construction of upstream hydropower dams.