DEER CAMERA SURVEYS: HELPING MANAGERS AVOID THE PITFALLS SETH BASINGER M.S. CANDIDATE UNIVERSITY OF TENNESSEE - FWF MAY 7, 2013 12:30 PM ROOM 160 PBB
OUTLINE Deer population estimators Why camera surveys??? Basic fundamentals of camera surveys Management benefits Deriving population estimates Assumptions Potential biases with camera surveys Literature and preliminary research Management impacts What managers should do
DEER POPULATION ESTIMATORS Track counts Spotlight counts Ground thermal infrared imaging (GTIR) Aerial vertical-looking infrared (aerial VLIR) Fecal pellet counts Camera surveys Odocoileus virginianus
DEER CAMERA SURVEYS Jacobson et al. (1997) Here to stay Private landowners: Easy to use Cheaper than most methods Visual documentation Used in Quality Deer Management Population trends (sex ratios, density) Herd health Fawn recruitment (predation) Harvest decisions Hunter excitement/involvement
SETTING UP A CAMERA SURVEY Pre- or post-hunting season 1 camera per 100 acres Bait attractants at camera sites Pre-bait ( 7 days), run cameras 10-14 days Tally # of bucks, does, fawns in pictures Determine # of unique bucks by antler characteristics
DERIVING POPULATION ESTIMATES Scenario: landowner has 300 acres Site 1 Bucks - 100 Does - 150 Fawns - 50 Site 2 Bucks - 60 Does - 25 Fawns - 25 Site 3 Bucks - 115 Does - 175 Fawns - 100 Total Bucks - 275 Does - 350 Fawns - 175 # of individual bucks = 15 Sex ratio = 350/275 = 1.27 doe:buck Does = 15*1.27 = 19 Fawns = 9 Total deer = 43 Deer density = 1 deer per 7 acres
ASSUMPTIONS BAITED SURVEY 1. Deer using the property are attracted to the survey bait sites 2. Relative attractiveness of the bait is similar each year 3. Bucks and does are equally attracted to the bait sites 4. Every unique buck photographed is identified accurately by the surveyor 5. A significant majority of deer using the property are photographed Jacobson et al. 1997, Edwards 2010
TRIGGERED CAMERA DELAY Surveys usually conducted between 5-15 min delay What if delay time changed from year to year??? Motion sensor Would this affect buck or doe capture detection??? Setup/delay switch
LIMITED RESEARCH Few have studied detection probability relative to delay time Jacobson et al. (1997) Potential bias in capture rate Sex-related vulnerability to trapping Acker SEDSG - 2012 Differences in detection probability for does relative to bucks with 5- min vs 10-min delay Weckel et al. (2011) On average, tagged does were photographed twice as often as bucks and fawns
SEX RATIO RELATIVE TO DELAY TIME Doe:buck Sex Ratio 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 1 min 5 min 10 min 20 min 30 min Delay Time
HETEROGENEITY BIASES Could differ from site to site, population to population: Camera placement/density Home range characteristics Nutritional demands Herd demographics
MANAGEMENT IMPACT Doe:buck ratio 2 1.5 1 0.5 0 1 min 5 min 10 min 20 min 30 min 1-min delay Doe:buck ratio: 2.21 33 identified bucks 73 derived does 42 derived fawns 148 total deer 1 deer per 5.4 acres 10-min delay Doe:buck ratio: 2.83 33 identified bucks 94 derived does 55 derived fawns 182 total deer 1 deer per 4.4 acres Actual Survey Results
CONSISTENCY IS KEY!!! Keep the same: delay time bait types camera sites survey timing & length Need consistency with trend data!
FUTURE DIRECTION More research with tagged & GPS-collared deer feeding time site visitation rates home range relations For now, stick to consistency
PICTURE REFERENCES www.knowyourwildlife.com www.floridastateparks.org www.blog.stickemarchery.com www.nrem.okstate.edu www.fivepointfarmcorn.com www.seedworldusa.com www.theinterneteducator.com Ryan Basinger Jared Beaver
LITERATURE REFERENCES Acker, P. K., S. Ditchkoff, C. Newbolt. 2012. Seeking improved efficiency of camera survey techniques for white-tailed deer. Proceedings of the 35 th Annual Meeting of the Southeast Deer Study Group. Destin, Florida, USA. Edwards, D. 2010. Introduction to trail-camera surveys. Pp. 100 121 in Deer cameras: The science of scouting. L. Thomas Jr, editor. Quality Deer Management Association, Bogart, Georgia, USA. Jacobson, H. A., J. C. Kroll, R. W. Browning, B. H. Koerth, and M. H Conway. 1997. Infrared-triggered cameras for censusing white-tailed deer. Wildlife Society Bulletin 25:547 556. Weckel, M., R. F. Rockwell, and F. Secret. 2011. A modification of Jacobson et al. s (1997) individual branch-antlered male method for censusing white-tailed deer. Wildlife Society Bulletin 35:445 451.
ACKNOWLEDGEMENTS Dr. Craig Harper Arnold Air Force Base Ryan Basinger Peter Acker Jared Laufenberg Daniel Hamm
QUESTIONS??? Seth Basinger pbasinge@utk.edu