Competition may lead to declines in American Kestrel (Falco sparverius) nest box use at the Ridgefield National Wildlife Refuge and its implications for management. (Murdock College Science Research Program Conference November 4-5, 2016 Spokane WA )
Declines in raptor populations have been well documented based on several measures. These collectively indicate long-term declines of American Kestrel (Falco sparverius) populations in numerous regions of North America. We report data from 13 years of nest box monitoring at the Ridgefield National Wildlife Refuge (Clark County) in southwest Washington, USA. American Kestrels occupied boxes 31 times while European Starlings attempted to use boxes 66 times over this period. Of the 31 nesting attempts by American Kestrels 22 were successful (65.7 %) over the thirteen year period. Kestrels laid 4.5 ±0.96 eggs per box. American Kestrel populations at the Ridgefield National Wildlife Refuge have declined steadily since 2005 as measured by nest box occupation and productivity. Our data suggests that one reason American Kestrels are declining on the refuge is due to the increase in competition for nesting cavities by European Starlings (Sturnus vulgaris). Management implications indicate eviction of starlings can increase American kestrel nesting attempts.
Investigating Genetic or Social Monogamy in American Kestrels (Falco sparverius)
While most species of raptor are listed as monogamous, it is unclear whether these are genetically monogamous (genetically exclusive parings for the season to rear young) or socially monogamous parings (for the season to rear young, with extra pair fertilization). Many passerines that were once believed to be genetically monogamous have been confirmed as socially monogamous. Limited data is available for raptors.
We have placed nest boxes appropriate for America Kestrels on the Ridgefield National Wildlife Refuge. Genetic analysis will be performed from blood samples taken and parental exclusion (Decker et al.1993, Marks, 1999) will be performed to determine the relatedness of the parents and offspring. All subjects will be banded with U.S. Fish and Wildlife Service bands to allow for the confirmed identification of individual birds within the study parameters.
We have placed nest boxes suitable for American Kestrel on the Ridgefield National Wildlife Refuge (WA). While most of our nest boxes are on closed areas of the refuge, two boxes are visible on the auto-tour rout on the "River-S Unit".
Ridgefield National Wildlife Refuge