Progress in restoring the aplomado falcon to southern Texas

Abstract

The northern aplomado falcon (Falco femoralis septentrionalis) was once fairly common in the savannas of southern Texas and in other parts of the American Southwest but virtually disappeared by the 1950s north of the Mexican border. It was federally listed as endangered in 1986. The Peregrine Fund established a captive breeding program based on 25 nestlings obtained from eastern Mexico during 1977‐1988. Following a pilot release project in 1985‐1989, a full‐scale release effort in the southern Texas plain began in 1993 employing techniques similar to those we developed for the peregrine falcon (Falco peregrinus). We produced 923 fledgling aplomado falcons, of which 812 were released in Texas on both federal wildlife refuges and private property. We observed released falcons breeding in the wild for the first time in 1995, and by 2002, 37 pairs were known and at least 87 wild young had fledged over an 8‐year period. Predation by raccoons (Procyon lotor) was a frequent cause of nest failure, and the great horned owl (Bubo virginianus) was the principal source of death in fledglings at hack sites, a factor that may limit aplomado falcon recovery in some areas of its former range. Enrollment of more than 5,500 km2 of private land under federally mediated “Safe Harbor” agreements encouraged landowner goodwill and cooperation and provided essential access to private property by affording relief from potential liability associated with the Endangered Species Act.

Effect of Sex and Age at Release on the Independence of Hacked Harpy Eagles

“…Our 70% hacking success when releasing younger eagles (5-7 mo old) was comparable to the survival rates of hacked juvenile raptors such as the Mauritius Kestrel (F. punctatus, 73%), Peregrine Falcon (75%), Aplomado Falcon (F. femoralis, 67%) and White-tailed Eagle (Haliaeetus albicilla, 73%; Barclay and Cade 1983, Green et al 1996, Jenny et al 2004, Nicoll et al 2004. Our 100% success rate for older (18-22 mo old) Harpy Eagles was likely a consequence of the shorter length of the dependence period and reduced risk of mortality that the dependence period entails.…”

Bayesian hierarchical model assessment of nest site and landscape effects on nest survival of aplomado falcons

“…We observed aplomado falcon breeding pairs during January to June 2002–2004. Most or all individuals were derived from captive stock resulting from a long‐term release program conducted by The Peregrine Fund (Jenny et al 2004). We found territorial pairs and identified banded individuals before the onset of breeding activities to minimize observer impact on behavior.…”

“…Little is known about possible effects of anthropogenic disturbances on the behavior or demography of the northern aplomado falcon ( Falco femoralis septentrionalis ) in its reintroduced range of southern Texas (Jenny et al 2004). The larger of the 2 known reestablished populations has inhabited a heterogeneous region of the Rio Grande Valley since 1992.…”

Prey Use and Provisioning Rates of Urban-nesting Mississippi Kites in West Texas

“…Health and growth of nestlings is likely dependent upon a relatively constant input of adequate nutrition. For example, to maximize their health and growth, captive-reared nestling raptors are fed 4 to 5 times daily (Fox 1995, Krijgsveld et al 1998, Jenny et al 2004. Although there was a 38.9% increase in biomass delivery rate in our study in 2011, prey delivery rate by number decreased by 156%; thus, some Mississippi Kite nestlings may have received the occasional ''large'' meal in 2011, but not a satisfactory amount of regularly delivered daily nutrition to facilitate growth and development.…”