PS 10-13 - Comparing productivity and nest success in Lewis woodpeckers Melanerpes lewis between grazed and ungrazed aspen Populus tremuloides stands

Tuesday, August 9, 2016
ESA Exhibit Hall, Ft Lauderdale Convention Center
Anna R. Miera, Jamie Jarolimek and Kerri T. Vierling, Department of Fish and Wildlife Science, University of Idaho, Moscow, ID

Lewis’ woodpeckers (Melanerpes lewis) often nest in the cavities of aspen trees (Populus tremuloides) and will utilize the aspen stand and surrounding area to gather the resources to fledge nestlings. Cattle released for grazing also make use aspen stands and immediate area, browsing on the understory vegetation. Cattle grazing has the potential to impact the nesting success and/or productivity of Lewis’ woodpeckers by overgrazing the vegetation that serves as vital habitat for the insects that are the woodpecker’s primary food source. Nest success is the percent of nests that successfully fledge at least one hatchling. Productivity is the proportion of fledged hatchlings out of total offspring hatched in a nest. While there have been studies comparing nest success and daily survival rate across types of habitats, there has been no study directly comparing nest success between grazed and ungrazed sites of the same habitat type for Lewis’ woodpeckers. Overgrazing could lead to the decline of nest success and productivity in Lewis’ woodpeckers. We observed nine Lewis’ woodpecker nests over a period of five weeks in 2015 to track nest success and productivity.


Our result showed that the average productivity was similar in ungrazed sites (0.375) compared to grazed sites (0.317), but nest success was higher in grazed sites (83%) than in ungrazed sites (67%). Information regarding the impacts of cattle on Lewis’ woodpeckers is vital to inform the management of livestock in sensitive areas of aspen habitat so as to ensure survival of the species.