Nest-scale Habitat Use by Pinyon Jay and Gray Vireo in the BLM Farmington Resource Area 2013−2014 Final Report Kristine Johnson1, Lynn Wickersham2, Jacqueline Smith1, Nathan Petersen,1 and John Wickersham2 1Biology Department, University of New Mexico & 2 Animas Biological Studies, Durango, CO Natural Heritage New Mexico Publication number 15-GTR-386 March 2015 Contents List of Figures ................................................................................................................................. 3 List of Tables .................................................................................................................................. 3 Abstract ........................................................................................................................................... 4 Introduction ..................................................................................................................................... 6 Pinyon-Juniper Habitat Declines ................................................................................................ 6 Recent Research on Habitat Use by Pinyon-Juniper Birds ......................................................... 6 2014 Accomplishments ............................................................................................................... 7 Methods........................................................................................................................................... 7 Study Areas ................................................................................................................................. 7 Field Methods ............................................................................................................................. 9 Derived and GIS Measurements ............................................................................................... 12 Analysis..................................................................................................................................... 12 Results ........................................................................................................................................... 13 Pinyon Jays ............................................................................................................................... 13 Gray Vireos ............................................................................................................................... 22 Discussion ..................................................................................................................................... 34 Pinyon Jays ............................................................................................................................... 34 Gray Vireos ............................................................................................................................... 35 Management Recommendations ............................................................................................... 36 Acknowledgments......................................................................................................................... 39 Literature Cited ............................................................................................................................. 39 2 List of Figures Figure 1. Pinyon Jay and Gray Vireo nesting areas at Farmington BLM, 2013−2014. ................. 8 Figure 2. Walk-in pigeon trap used to capture Pinyon Jays. ........................................................ 10 Figure 3. Modified Australian crow trap used to capture Pinyon Jays. ........................................ 10 Figure 4. Pinyon Jay with transmitter. .......................................................................................... 11 Figure 5. Pinyon Jay nests found at Rawhide Canyon in 2013 and 2014. .................................... 14 Figure 6. Pinyon Jay nests found at Old Rawhide, 2012−2013, and Crow Mesa, 2013-2014. .... 15 Figure 7. Tree RCDs on Pinyon Jay nest and random plots. ........................................................ 17 Figure 8. Tree heights on Pinyon Jay nest and random plots. ...................................................... 18 Figure 9. Locations of Pinyon Jays between 15 April and 14 October 2014. .............................. 21 Figure 10. Gray Vireos observed at Aztec, 2013 and 2014. ......................................................... 23 Figure 11. Gray Vireos observed at Crow Mesa, 2013 and 2014. ................................................ 25 Figure 12. Gray Vireos and nests observed at Mount Nebo, 2013. .............................................. 26 Figure 13. Gray Vireos observed at Pump Canyon and Pump Mesa, 2013 and 2014. ................. 27 Figure 14. Gray Vireo nests at Aztec, 2013 and 2014. ................................................................. 28 Figure 15. Gray Vireo nests at Crow Mesa, 2013 and 2014. ........................................................ 29 Figure 16. Gray Vireo nests at Pump Canyon and Pump Mesa, 2013 and 2014. ......................... 30 Figure 17. Distribution of tree density on Gray Vireo nest plots in the BLM Farmington Resource Area, 2013−2014. .......................................................................................................... 31 List of Tables Table 1. Summary statistics for Pinyon Jay nest and center random plot trees. ........................... 16 Table 2. Variables and attribute type in final model set for Pinyon Jay nest vs. random plot analysis. ......................................................................................................................................... 18 Table 3.Candidate model set of conditional logistic regression models discriminating Pinyon Jay nest plots from unused plots, 2012−14. ........................................................................................ 19 Table 4. Parameter estimates from best candidate conditional logistic regression model discriminating Pinyon Jay nest plots from random plots, 2012-14. ............................................. 19 Table 5. Transmitters attached to Pinyon Jays in 2014. ............................................................... 20 Table 6. Number of Gray Vireo territories and nests identified in the BLM Resource Area study sites, 2013–2014. .......................................................................................................................... 24 Table 7. Nest tree height and mean canopy width for Gray Vireo nests in the BLM Farmington Resource Area, 2013−2014. .......................................................................................................... 31 Table 8. Topographic and infrastructure variables of Gray Vireo nest locations in the BLM Resource Area study sites, 2013–2014. ........................................................................................ 32 Table 9. Candidate model set of conditional logistic regression models discriminating Gray Vireo nest plots from random plots.. ............................................................................................ 33 Table 10. Parameter estimates from the best candidate conditional logistic regression model discriminating Gray Vireo nest from random plots in the BLM Farmington Resource Area, 2013−2014. ................................................................................................................................... 34 3 Abstract We studied nest-scale habitat requirements of Pinyon Jay and Gray Vireo in the BLM Farmington, NM Resource Area. Pinyon Jays nested at Rawhide Canyon and Crow Mesa from 2013−2014 and one additional site near Rawhide Canyon in 2012−2013. Pinyon Jays placed nests (n=56) in roughly equal proportions in pinyon and juniper trees. Using conditional logistic regression, we compared habitat on BBIRD plots at nests to random plots within nesting colonies. The best model comparing nest to random plots indicated that Pinyon Jay nest trees were significantly taller and larger in diameter than central trees on random plots, but the jays did not nest in the very tallest, emergent trees. The use of larger-than-random trees for nests is consistent with our results in a previous study on DoD installations, except that in that study, canopy cover at the nest plot and litter under the nest tree were included in the best nest-scale model. The density of trees on nest plots in the DoD study was over twice that at BLM. We attached transmitters to 11 Pinyon Jays and collected data on their locations from 10 June−14 October. These provided 44 transmitter-weeks of data and 81 detection points, a mean of 7.4 detections per bird. These location data provided three estimates of home range area for the Rawhide flock from mid-April to mid-October: 3102.88 ha (MCP), 4033.66 ha (95% Kernel Density Estimator), and 4200 ha (all 100-ha detection blocks and interconnecting blocks). These areas are larger than most home ranges reported in the literature. We recorded 229 detections of Gray Vireos at the five study sites in 2013 and 2014, including males, females, pairs, and fledglings. We found 120 territories in 2013 and 95 in 2014 at all sites. Juniper dominated the Aztec, Pump Canyon, and Pump Mesa Gray Vireo territories, with mean juniper to pinyon proportion of 0.95, 0.82 and 0.80, respectively. Territories on Crow Mesa were dominated by pinyon (mean nest plot juniper to pinyon proportion, 0.32). Combining years and sites, 53 (82%) Gray Vireo nests were in juniper