Wintering Bird Occupancy and Detection in Response to Proximity to Water and Eastern Screech-Owl Call Playback

Transcription

1 Wintering Bird Occupancy and Detection in Response to Proximity to Water and Eastern Screech-Owl Call Playback Megan King Jens Kosch Kristen Lewey Mary Osborn April Boggs Amber Bledsoe

2 Introduction Dr. Thomas Quay s research studied winter bird communities in varying habitats in Raleigh, NC Our work continued the study of winter bird species Tested covariates to further understand bird species population dynamics Screech Owl playback 715/EntryId/95/The-Christmas-Bird-Count-is-On.aspx Distance to water source

3 Background Information on Covariates Distance to Water: Species richness in riparian areas have yielded mixed results (McDonald et al. 2006). Potential correlation between songbird abundance and the order of streams adjacent to riparian forest patches (Beyeler 2009). Eastern Screech Owl playback: Mobbing call playback did increase the detection rates for some species it also decreased the detection rates for other species (Rea et al. 2015). Alarm calls and mobbing calls lead to alarm calls of other prey species in the area (Magrath et al. 2007).

4 Hypotheses Screech Owl playback increases detection probability of birds. As distance to water decreases, occupancy of birds increases.

5 Points were randomly selected using ArcGIS and data from Wake COunty GIS Methods Location: William B Umstead State Park and Schenck Forest 20 points surveyed 3 times each Point count survey 5 minutes each Half surveys with owl playback at beginning Half surveys without owl playback Presence/Absence recorded for each species seen or heard in unlimited radius of sampling point

6 Map of Sampling Locations

7 Assumptions Independent sampling points Each point is random Equal detection and occupancy probability for each species Each sampling site is closed

8 Statistical Analysis Used R to analyze results using library unmarked Tested occupancy and detection on the covariates Owl playback Distance to water AIC Models used to find best model for occupancy Species of interest: Mourning Dove Carolina Wren Carolina Chickadee Tufted Titmouse Red-Bellied Woodpecker Pine Warbler (Fiske and Chandler 2011, Fiske et al. 2015, MacKenzie et al. 2002)

9 Naive Occupancy and Detection Species Overall Naive Occupancy Rate Naive Occupancy Rate for Visit 1 Naive Occupancy Rate for Visit 2 Naive Occupancy Rate for Visit 3 Total Number of Detections Mourning Dove Carolina Wren Carolina Chickadee Tufted Titmouse Red-Bellied Woodpecker Pine Warbler

10 Best Models for Each Species Bird Species AIC AICwt Occupancy Estimate Detection Estimate Best Model Mourning Dove Null Model Carolina Wren Null Model Carolina Chickadee Null Model Eastern Tufted Titmouse Red-bellied Woodpecker Screech Owl on Detection Distance to Water on Occupancy Pine Warbler Distance to Water on Occupancy

11 Results: Screech Owl Playback Lower detection of Eastern Tufted Titmouse with Screech Owl playback No significant difference in occupancy with Screech Owl playback for other species of interest.

12 Results: Distance to Water

13 Results: Distance to Water Red-bellied Woodpecker occupancy was negatively associated with distance to water Pine Warbler occupancy was positively associated with distance to water Other species of interest showed no significant correlation with occupancy

14 Discussion: Screech Owl Playback It was hypothesized that birds would respond to Screech Owl playback with alarm calls, thus increasing detectability (Courter and Ritchison 2012) Tufted Titmouse less likely to be detected with owl

15 Discussion: Distance to Water Woodpecker and Pine warbler results consistent with typical habitat River bottoms and wetlands habitat for Red-Bellied Woodpeckers More suitable pines farther from water sources or meet their water needs through their habitat in other ways (Winkler and Christie 2010; The Cornell Lab of Ornithology; Animal Diversity Web; Schroeder 1982)

16 Possible Sources of Error Variable observer skill Level Loud Screech Owl playback m ay have im peded the observers ability to hear calls in the first 2 minutes. There m ay be ephem eral water sources that are not accounted for. We may have accounted for water sources that are not permanent

17 Conclusion Overall trend is native wintering birds surveyed did not occupy sites based on the proximity of the site to water With the increased fragmentation of forests, monitoring the response of the bird communities is important Future studies: Habitat selection for particular species of native wintering birds Fragmentation of habitat

18 Questions?

19 Citations Beyeler, S.C. (2009). Factors affecting songbird richness, abundance, and nest survival in riparian forests in a midwestern agricultural landscape. Ph. D. dissertation, University of Illinois at Urbana-Champaign, Urbana, IL, USA. Courter, J. and G. Ritchison (2012). Asymmetries in mobbing behavior among nuclear flockmates. The Wilson Journal of Ornithology 124(3): Available from: Fiske, I. and R. B. Chandler (2011). Unmarked: An R package for fitting hierarchical models of wildlife occurrence and abundance. Journal of Statistical Software 43:1 23. Fiske, I., R. Chandler, D. Miller, A. Royle, M. Kery, J. Hostetler, R. Hutchinson (2015). Package unmarked (Models for Data from Unmarked Animals). Web. Available from: MacDonald, S.E., B. Eaton, C.S. Machtans, C. Paszkowski, S. Hannon, and S. Boutin (2006). Is forest close to lakes ecologically unique?: Analysis of vegetation, small mammals, amphibians, and songbirds. Forest Ecology and Management 223(1-3): doi: /j.foreco MacKenzie, D. I., J. D. Nichols, G.B. Lachman, S. Droege, J.A. Royle, and C. A. Langtimm (2002). Estimating site occupancy rates when detection probabilities are less than one. Ecology. 83(8): Magrath, R.D., B.J. Pitcher, and J.L. Gardner (2007). A mutual understanding? Interspecific responses by birds to each other s aerial alarm calls. Behavioral Ecology 18: "Pine Warbler." N.d. Life History, All About Birds. The Cornell Lab of Ornithology. Web. 07 Apr < Rae, L.F., D.M. Whitaker, and I.G.Warkentin (2015). Variable effect of playback of chickadee mobbing calls on detection probability of boreal forest birds. Journal of Field Ornithology. 86(1): doi: /jofo "Red-bellied Woodpecker." N.d. Life History, All About Birds. The Cornell Lab of Ornithology. Web. 07 Apr < Schroeder, R.L. (1982). Habitat suitability index models: Pine Warbler. U.S. Fish and Wildlife Service, Biological Services Program and Division of Ecological Services FWS/OBS-82/ pp