Birder's Guide

OCT 2014

Birder's Guide is the American Birding Association's newest publication. Each issue focuses on a key subject, providing tips from experienced birders on a wide variety of topics like Travel, Listing & Taxonomy, Gear, and Conservation & Community.

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Page 43 of 57

36 Birder's Guide to Listing & Taxonomy | October 2014 Aplomado Falcons in the ABA Area ings in 1980 in Proceedings of the 17th International Ornithological Congress, avail- able at . A more recent study reported by Miguel A. Mora and colleagues in 2008 (Environment International 34:44–50) in- dicated that DDE and other toxic con - taminants may no longer be a threat to Aplomado Falcon reproduction in south Texas, but they may still be having nega- tive effects on Chihuahuan populations. No study has been suffciently extensive to assess the degree of DDE contamination and possible reproductive failure in the species as a whole. C ould the Aplomado Falcon possibly be restored in some portion of its original U.S. range? A large-scale at- tempt at restoration began in the early 1990s, led by The Peregrine Fund (the organization famed for its role in increas- ing the Peregrine Falcon's numbers). The story of this major conservation effort is summarized in a 2013 review by W. Grainger Hunt and 12 coauthors in The Journal of Raptor Research (47:335–351). More than 1,800 Aplomado fedglings bred in captivity by The Peregrine Project were released in their natural habitat by hacking during a decade-long period. In coastal south Texas, 839 were released at 21 sites during 1993–2004, supple- mented by releases of 35 individuals split between two additional sites in 2012. In western Texas, 637 birds were hacked at 11 sites during 2002–2011. In southern New Mexico, 337 birds were released at 10 sites during 2006–2012. Hunt, a senior scientist at The Peregrine Fund, says that reproduction has tended to be good in south Texas, with yearly averages of 1.5 to 1.9 fedglings per ter- ritorial pair, and that perhaps at least 500 young have fedged since 1995. Much of the success in south Texas is attributed to a novel design of artifcial nest structures that prevent predation by Great Horned Owls, another factor thought to be in - volved in failures of Aplomado nests. Geographically, the success has differed notably. Numbers in two coastal Texas populations have remained fairly stable since 2008. A Matagorda Island popula- tion and a Brownsville area population each had 14 pairs in 2013. But the story is discouragingly different in west Texas and New Mexico, where not one pair could be found by 2012. Correspondingly, future conservation efforts must differ, according to Hunt and his colleagues: • They believe that the Matagorda Island population near Rockport is likely secure as it is presently managed. However, they warn that the Brownsville area pop- ulation is threatened by human develop- ment and predation by brush-associated raptors. This latter area requires new protection and habitat management, as well as establishment of additional large areas of open savanna in coastal Texas. (The densest Aplomado aggregation lies between Brownsville and Texas Highway 100 west of Port Isabel—many birders' favorite location for fnding the species.) • By contrast, the authors believe programs in western Texas and southern New Mexico cannot succeed under current environmental conditions. Their conclu- sion is that "Given long-term predictions of increasing drought, it is questionable whether Aplomados can regain their former distribution in the Chihuahuan Desert." Thus, reintroduction may have failed in that region at least partly be- cause of low prey availability. Artifcial nest structures, called hacking platforms, protect young Aplomados from predators such as Great Horned Owls. This structure is in New Mexico. Photo © Nick Dunlop

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