Low risk of marking-induced abandonment in free-ranging white-tailed deer neonates

Abstract

Marking-induced abandonment has been suggested as the most common cause of mark- ing-induced mortality of free-ranging, newborn ungulates in North America. However, there has been no direct study of marking-induced abandonment in free-ranging ungu- lates, and its relevance to neonate survival is inconclusive. We describe our capture, marking, and monitoring of white-tailed deer (Odocoileus virginianus) neonates born to radiocollared dams in north-central Minnesota over 5 springs (1997, 1999–2002), as it relates to marking-induced or natural abandonment. We assumed that all neonates dying within 4 days post-marking were possible occurrences of abandonment. We captured 89 neonates; 6 (7%) died within 4 days (4 to predation, 2 to unknown causes). We found no conclusive evidence of marking-induced abandonment. Handling had no impact on neonate survival, even though nearly 40% of neonates were handled >15 minutes. Time of marking (post-parturition) was similar among survivors and nonsurvivors; 48% of sur- viving neonates were captured <24 hours after birth. Eleven neonates (12%) were chased prior to capture, and all survived >4 days post-capture. Hematology, serum indices of nutritional restriction, and body fat content of dams were similar among all neonates. Dams of nonsurviving fawns were older than dams of survivors (8.5 ± 2.1 vs. 5.6 ± 0.4 years). Neonates traveled a mean distance of 162 ± 8 m from their capture site <4 days post-marking, and 76% of all radiocollared dam locations (n = 245) were <200 m from their neonates. Mean distance traveled between capture and mortality sites for nonsur- vivors (159 ± 69 m, n = 6) was similar to mean travel distance of the surviving, radio- tracked neonates (162 ± 8 m, n = 18) within 4 days post-marking. Our findings suggest that risk of marking-induced abandonment in white-tailed neonates is minimal; thus, omission or censoring of suspected cases of marking-induced abandonment in white- tailed neonate survival studies may underestimate natural mortality rates.