Does Predation Influence the Seasonal and Diel Timing of Moose Calving in Central Ontario, Canada?

Abstract

Birth synchrony is well documented among ungulates and is hypothesised to maximize neonate survival, either by minimizing the risk of predation through predator swamping or by synchronising birthing with increased seasonal food availability. We used encapsulated vaginal implant transmitters to locate and capture neonatal moose calves and document the seasonal and diel timing of parturition in two adjacent study areas with different predation pressure in central Ontario, Canada. We tested the hypothesis that predation promotes earlier and more synchronous birth of moose calves. Across both areas, proportionately more births occurred during the afternoon and fewer than expected occurred overnight. Mean date of calving averaged 1.5 days earlier and calving was also more synchronous in the study area with heavier predation pressure, despite average green-up date and peak Normalized Difference Vegetation Index date occurring 2 days later in this study area than in the area receiving lighter predation pressure. We encourage analysis of data on timing of parturition from additional study areas experiencing varying degrees of predation pressure to better clarify the influence of predation in driving seasonal and diel timing of parturition in temperate ungulates.

Fig 1. Location of study sites in Algonquin Provincial Park (APP) and Wildlife Management Unit 49 (WMU49) in central Ontario, Canada.

The 2 study sites are hatched.

Fig 2. Parturition date of radio-collared adult female moose, in Algonquin Provincial Park (APP) and Wildlife Management Unit 49 (WMU49) in central Ontario, Canada, 2007–09.

Fig 3. Diel time of parturition for 39 radio-collared adult female moose, central Ontario, Canada, 2007–09.

Fig 4. Age distributions of radio-collared female moose in Algonquin Provincial Park (APP) and Wildlife Management Unit 49 (WMU49), central Ontario, Canada, 2006–07.