Behavior & cause-specific mortality of Mule Deer (Odocoileus hemionus) fawns on the National Rifle Association Whittington Center of North Central New Mexico

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2013-08

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Abstract

Declining trends have been reported in most mule deer (Odocoileus hemionus) populations in New Mexico and other western states. This includes the Rocky Mountain mule deer (Odocoileus hemionus hemionus) population on the National Rifle Association Whittington Center (WC) in north-central New Mexico where our study was conducted. Our objectives were to determine causes of mortalities of mule deer fawns and estimate seasonal survival rates. We hypothesized low fawn survival rates due to high predation rates by Black bears (Ursus Americana). We radio marked fawns (n=50) born on the WC during 2011 and 2012. We applied a series of biological covariates (age, sex, birth weight, resistance, stability, vocalization, total body length, chest girth and habitat types) to estimate survival rates at 14 days post capture and weekly survival through summer and fall. Survival analyses were performed using Program MARK (6.2). We implemented corrected Akaike’s information criteria (AICc) to determine covariates that were significant to survival. Our observations suggested the habitat types where fawns were captured might have been correlated to survival, but we failed to detect a significant relationship. Predation was the major source of neonate mortality accounting for 86.8% of deaths. Black bear were the highest source of predation on fawns ( 57.5%, n=19) and total mortality (49.9%), verifying our hypothesis. Coyotes (Canis latrans) were the second highest predation source ( 36.3%, n=12) and total mortality (31.6%). Eight month mean survival estimate was 24.4%. These survival estimates are slightly higher than those from a previous investigation in the same area. We also observed and analyzed behaviours of fawns from parturition to two weeks of age that influenced mortality rates. I intended to develop recommendations that landowners and game agencies can use to manage habitats and help reduce declines of mule deer populations.

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Keywords

Mule deer, Fawn, Neonate mortality, New Mexico, NRA Whittington center, Predation, Survival, Habitat type, Fawn behaviour, Doe-fawn pair

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