Deer-Elk Ecology Research Project

Transcription

1 Deer-Elk Ecology Research Project 2016 Summer Update Spring helicopter captures for the DEER Project wrapped up in late April this year. Given concerns about potentially missing migratory animals that move into the Greater Little Mountain area for summer, captures were later than normal; spring capture work is typically mid-march. During our capture efforts, we finished deploying collars on adult female mule deer and elk. We also re-deployed collars from adult mortalities that occurred over the winter months. This capture brought our sample size up to 53 adult female mule deer and 35 adult female elk. During capture events, we assessed body condition using ultrasonography and a palpation score. Ultrasonography, with a device similar to what you might see at a doctor s office, is used to assess the amount of fat reserves and thickness of various muscles. A combination of ultrasound and body palpation scoring Helicopter transporting a recaptured deer (top) and a Vaginal Implant Transmitter (bottom). allow us to estimate the percent body fat of individuals and to evaluate how it has fared over the winter months. We also evaluate pregnancy and if pregnant, we fit females with Vaginal Implant Transmitters (VIT). The transmitters allow us to determine when and where animals give birth, and help in capturing fawns. Once measurements are collected and collars are fit, animals are released and typically return to where they were captured within a day.

2 Dr. Kevin Monteith measuring body condition of a mule deer (left). Comparison of average (± SE) mule deer body fat between the November 2015 and April 2016 captures (bottom). Spring captures showed that mule deer lost over 50% of their body fat reserves between November 2015 and April Given that we were capturing animals in relatively late-term of pregnancy, it was challenging to determine the number of fetuses because of their size. Pregnancy rate was 98% and estimated fetal rate, using ultrasonography coupled with data from fawn captures, was 1.4 for mule deer in the Greater Little Mountain Area (GLMA). This corresponds with roughly 73 fawns being born to our collared animals. One key reason we captured in late April was to attempt to collar any migrants as they arrived back on summer range in the GLMA. The movements we have observed thus far seem to indicate that the collared animals in this system migrate short distances. Nonetheless, these newly collared animals will help demonstrate the full range of migratory patterns as they head to winter ranges this fall. Elk (left panel) and mule deer (right panel) since May 1, Note the migrations by mule deer across the Greater Little Mountain Area.

3 Collared mule deer fawn inspecting researchers before laying back down to hide. Timing of mule deer fawn captures in the Greater Little Mountain Area. The field crew, led by PhD student Matt Hayes, arrived in the field in late May to prepare for fawn capturing and fecal sample collection. Fawn capture and collaring is aimed at understanding survival of fawns, recruitment into the population, sex ratio and, if fawns die, determine why. We captured a total of 55 fawns from 36 adult deer (~70% of the pregnant deer). Of those, 55 fawns, 32 were females and 23 were males. We observed 14 mortalities thus far. The biggest proximal cause of fawn mortality at this time was predation (9 mortalities linked to predation), with the leading predator being coyotes (5 mortalities). We have observed two feline and one bear related mortality as well as a currently unknown predator. Two fawns were stillborn or died shortly after birth and three were either related to accidents (e.g., brush entanglement) or the cause of death will be determined by necropsy. Fawn mortalities by: witnessed coyote attack (left), accidental lodging in sage brush (middle) and feline predation (right).

4 Locations of fawn captures (blue pins) and fawn mortalities (red symbols) in the GLMA. Average distances between collared animals and aspen stands during parturition in Interestingly, collared mule deer rarely were using aspen stands during parturition events or during the month of parturition. This is in contrast to what might be expected given previous research and local knowledge. It is thought that aspen stands play a critical role for mule deer, particularly during parturition. On average, our collared mule deer were over half a mile from aspen stands during parturition while our collared elk were nearly a mile from aspen stands. This is not to say that aspen is not important to mule deer, rather that more remains to be understood as to the role that aspen plays in this and perhaps other systems. Though we have yet to analyze the movement data, there appears to be more going on behind the scenes that we hope to elucidate. During the month of June, we have also kept a close eye on where elk have been. Although we did not deploy VITs in elk, we coarsely looked at where elk were at on the landscape during the parturition time window. There appears to be a high degree of separation between where deer and elk are spending their time during parturition. Density of elk (red) and mule deer (black) in the GLMA during June 2016.

5 With the fawn captures behind us, the field crew is now focusing efforts on collecting fecal samples from both our collared deer and collared elk ranges. Fecal samples will be analyzed to examine dietary overlap between elk and deer. In addition we are collecting any incidental fecal samples, including: pronghorn, feral horse and livestock. The goal is to collect three rounds of fecal samples per year to detail dietary overlap throughout the summer months. Fresh elk fecal sample used to determine dietary overlap with mule deer. Presumably, diets will shift as moisture decreases, plants senesce, and their relative quality and abundance changes. Once we analyze fecal samples to identify diet composition, subsequent summers we also will be collecting plant samples from key forage species to measure nutritional quality of those plants. With a single round of fecal samples collected, we have obtained nearly 900 individual fecal samples across the GLMA. Knowledge of diet composition will be key to evaluating potential dietary overlap among ungulate species, but also to help understand what key forage items help to grow mule deer in this arid landscape. Mule deer fawn twins, female on the left and male on the right (top). One of only two mule deer fawns captured in an aspen stand (left).

6 The Deer-Elk Ecology Research Project would not be possible without generous contributions and continued support from the Wyoming Game and Fish Department, Muley Fanatic Foundation Headquarters, the Southwest, Kemmerer, and Casper Chapters of the Muley Fanatic Foundation, Wyoming Governor s Big Game License Coalition, Bureau of Land Management, and Bowhunters of Wyoming. A special thanks to those hunter-conservationists that have invested in the DEER Project through the grass-roots fundraising efforts led by the Muley Fanatic Foundation. For more information: University of Wyoming Wyoming Game and Fish Kevin Monteith Matthew Hayes Patrick Burke Mark Zornes kevin.monteith@uwyo.edu mhayes1@uwyo.edu patrick.burke@wyo.gov mark.zornes@wyo.gov Kevin Spence kevin.spence@wyo.gov