PS 18-46 - Red-naped sapsucker nest cavity selection in City of Rocks

Tuesday, August 8, 2017
Exhibit Hall, Oregon Convention Center
Isabel Robles, Jamie Jarolimek and Kerri T. Vierling, Department of Fish and Wildlife Science, University of Idaho, Moscow, ID

We conducted this study at City of Rocks National Reserve in southern Idaho. The red-naped sapsucker (Sphyrapicus nuchalis: RNSA) is one of the woodpeckers that inhabits the area and creates nest cavities in quaking aspen (Populous tremuloides: POTR). Previous studies have focused on the heartwood decay of nest cavity trees, but there is limited information about how the vegetation surrounding these trees influences the RNSA nest cavity tree selection. This study investigates whether the surrounding tree communities influence which trees RSNA select for their nest cavities. We predicted that POTR with RNSA cavities will be surrounded by fewer trees than POTR without cavities. Also, we predicted that the trees surrounding focal trees with cavities would be smaller than the trees surrounding focal trees without cavities. We sampled 36 POTR total, 18 with active nest cavities and 18 random trees without nest cavities. From each of these focal trees we measured a 11.3m radius. We counted all trees within this radius and measured their diameter at breast height (DBH).


We analyzed the data using general logistic modeling in the program R. We found no significant relationship between the number of trees surrounding focal POTR and RNSA choice of tree to create cavities in. Similarly, we did not find a significant relationship between the size of trees surrounding the focal tree and RNSA tree selection. This data does not support our hypothesis that RNSA select trees that are surrounded by fewer trees. A possible explanation for this could be that being surrounded by more trees can provide RNSA more opportunity to create sap wells, their primary food source in City of Rocks, in trees near the cavities.