Notes on neonatal captures

Welcome to the Washington Predator-Prey Project Website. While various components of this research have been underway since 2016, we began large-scale data collection across the project this summer.  

For my research on carnivore-ungulate interactions, this was the second season of collaring white-tailed deer fawns, and the first season collaring elk calves. Thanks to the hard work of our field crew and collaborators, we deployed 27 radio-tracking collars on fawns and 16 collars on elk calves this year. Combined with the 19 collars deployed on fawns last year, we have monitored a total of 62 neonates for the project so far.

So how do we find these newborn animals to study? Sometimes, we can identify if a doe or cow has young by closely observing her behavior, which can indicate the general location of a fawn or calf. We also monitor the locations of GPS (Global Positioning Satellite) collared adult deer and elk, and can often pinpoint a birth site by a substantial reduction in maternal movement. A subset of GPS collared does and cows are fit with transmitters that alert us when they’ve given birth and mark the location of the birth site. By carefully searching these areas we may find the newborn fawn to collar and study.

Last year, Dr. Melia DeVivo, Dr. Matt Vander Hagen and I were on the search for one such birth site, in hopes of finding a fawn there. We followed a radio telemetry signal toward a transmitter marking the birth bed half a kilometer away. Bushwhacking through the thick understory, Melia heard a small grunt and froze mid-step. Inches in front of her boots, a speckled newborn fawn lay nestled under a snowberry shrub. With its tawny hide and white spots mimicking dappled sunlight on dry pine needles, the fawn was perfectly camouflaged. We got lucky that day and were able to collar this fawn and the one we were looking for.

Here, a white-tailed deer fawn hides in the understory after a capture. While deer and elk have precocious young, they’re still too slow to outrun many threats for the first week of life. So, they rely on cryptic hiding as a defense strategy. The mother will feed at a distance, keeping an eye on her hidden young. This is the reason many well-intentioned people find solitary fawns, assume they are abandoned and try to rescue them if the mother is out of sight.

Folds in the collar and elastic material will allow the collar to expand as this white-tailed deer fawn grows. We use blindfolds and cotton earplugs during the collaring to minimize stimulation and help keep the animals calm.

One of the questions we commonly receive about our efforts is how we ensure these collars continue to fit the fawns and calves as they grow. The collars we use are made from an elastic band. This band is folded over in pleats which are lightly stitched closed. Over time, the stitching wears out and the collars expand to fit growing necks. After about a year, the material wears out completely and the collars drop off the animals. The collars weigh less than 3% of the animal’s weight so that their activities are not impeded.

Once an animal has been collared, we listen to the radio signal periodically to locate the fawn or calf and check if it is alive. When the collar hasn’t moved for a pre-programmed period of time, the frequency of the radio signal changes to indicate a mortality or dropped collar. We follow this signal to locate the collar and investigate any mortalities to identify the cause of death. Incorporating these data into population models can help us identify which pressures the populations are most sensitive to.
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For the next year, we will continue to monitor these and adult ungulate and investigate patterns of mortality and habitat use. Stay tuned to follow our progress get updates from the rest of the team.
- Taylor Ganz