Ten Years of Raptor Nest Surveys in the Great Basin

HWI recently completed a comprehensive report based on annual raptor nest surveys in northwestern Utah from 1998-2007.  The objective of this report was to provide land managers with baseline raptor inventory and nest-monitoring data from the region and establish a scientifically defensible basis for making management decisions that help maintain ecosystem integrity and the area’s nesting raptors.  The data resulted in some significant findings and management recommendations.  For the full report, click here.

SPECIES OF FOCUS AND DESIGNATIONS:IMG_1471

  • Golden Eagle (Aquila chrysaetos)
  1. Although Golden Eagles are not yet afforded any special status, long-term nesting studies in the Snake River region of Idaho and in north-central Utah, as well as regional migration-count indices, confirm significant declines in nesting activity and overall populations, with large-scale loss and degradation of native shrubsteppe habitat believed to be the principal cause of declines in the Intermountain region.
  • Ferruginous Hawk (Buteo regalis)
  1. Listed as a Wildlife Species of Concern in Utah
  2. Recognized by the PIF North American Landbird Conservation Plan for the Basin & Range Physiographic Area as priority species in relation to conservation of shrubsteppe, sagebrush grassland, and pinyon-juniper habitats
  • Red-tailed Hawk (Buteo jamaicensis)
  • Swainson’s Hawk (Buteo swainsoni)
  1. At the onset of the study listed as a species of concern in Utah and it is still recognized as a Partners in Flight (PIF) Continental Watch List species
  2. Recognized by the PIF North American Landbird Conservation Plan for the Basin & Range Physiographic Area as priority species in relation to conservation of shrubsteppe, sagebrush grassland, and pinyon-juniper habitats
  • Peregrine Falcon (Falco peregreinus)
  • Prairie Falcon (Falco mexicanus)
  1. Recognized by the PIF North American Landbird Conservation Plan for the Basin & Range Physiographic Area as priority species in relation to conservation of shrubsteppe, sagebrush grassland, and pinyon-juniper habitats
  • Burrowing Owl (Athene cunicularia)
  1. Listed as a Wildlife Species of Concern in Utah

 

 

 

STUDY AREA:gbrns_web_map

  • The study area in northwestern Utah was roughly bounded to the south by I-80, to the north by the Idaho border, to the west by the Nevada border, and to the east by the western margins of the Great Salt Lake.

 

CONCLUSIONS AND MANAGEMENT IMPLICATIONS:

Based on the results of the long-term surveys, HWI recommends:

  • The importance of a territory focus for the monitoring and/or protection of nesting raptors, as individual nests typically are not independent entities.  Additionally, our documentation of both regular inter-annual nest fidelity and gaps in activity of three or more years has important implications for the management of individual nests.  Our results suggest that extending 5-years of protection to inactive nests (from the last documented activity) may be a reasonable management prescription; however, longer between-use intervals are fairly common.  More importantly, we strongly encourage adoption of standards that stipulate equivalent protection for all known alternate nests within a territory regardless of which nest was used most recently.
  • Highlights the difficulties of adequately monitoring Burrowing Owls with typical, community-level raptor nest-monitoring protocols.  We suggest that, in the absence of a more advanced understanding of individual territory dynamics, surveyors focus on the overall occupancy, activity, etc. of entire “burrow complexes” (i.e., spatially clumped burrows distinct from other burrow clumps). 
  • We suggest that local land managers pay particular attention to the relatively high raptor nesting activity in the Grouse Creek Valley and Prohibition Springs area, and consider educating local private landowners about the importance of their lands for nesting raptors.
  • Additional research into the complicated relationships between invasive vegetation and Ferruginous Hawk and Burrowing Owl nesting ecology warrant further investigation
  • Further advance our collective, detailed understanding of the ecology of the northwest Utah raptor community, which will require the addition of an extensive and rigorous program to simultaneously monitor prey abundance in the region.