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November 2016 Captures

Fall 2016 captures occurred the first week of November, where we deployed or recaptured 53 collars on adult female mule deer, and 35 collars on adult female elk. We also captured and collared 15 adult mule deer bucks to better understand their habitat use and movement during different times of the year.

During fall capture events, we assess body condition using ultrasonography and a palpation score. Ultrasonography is used to assess the amount of fat reserves and thickness of various muscles. A combination of ultrasound and body palpation scoring allows us to estimate the percent body fat of individuals and to evaluate how much fat they accumulated on summer range.




Mule Deer Bucks

The GLMA is a popular destination for mule deer hunters, but despite its popularity, evidence from Wyoming Game and Fish surveys suggest that buck:doe ratios have decreased in the past decade. Additionally, anecdotal evidence from locals suggest that mule deer bucks are harder to find during hunting season than previous years. This spurred increased interest in determining what is happening with mule deer bucks in this population and adds to the ongoing work of the DEER Project. So, during the November 2016 helicopter captures of the DEER Project, we kicked off the buck portion of our work. We captured and collared 15 mule deer bucks between 1 and 5 years old, and plan to collar an additional 25 new bucks each year of the project.

While we don’t know what is happening with the male segment of the population, our capturing and collaring efforts will yield significant evidence as to what might be going on. One possible explanation for the apparent lack of males observed in this system could be either dispersal movements or early migrations to neighboring areas or states just prior to hunting seasons. As we obtain more data and increase our sample size, we’ll be able to better understand the recruitment and movement of the male segment of the population. Stay tuned for more information as it becomes available!




Summer 2016 Fawn Season Recap

We captured 55 fawns from 36 adult deer (~70% of the pregnant deer). Of the 55 fawns captured, 32 were females and 23 were males. Between the date of parturition and the end of our intensive monitoring period in August 2016, we observed 30 mortalities (54% loss). 15 of those fawn loses were due to predation events including: coyotes, feline, and one bear-related mortality. Several other fawns died from malnutrition or disease with a few accidental mortalities, 1 stillborn and 4 unknown. Unknown mortalities occur when there is not enough of the fawn remaining to make a confident decision on cause of death.

We could not ascertain cause of death of several fawn mortalities, so we sent them to the Wyoming State Veterinary Lab (WSVL) for necropsies. So far, necropsy results suggest that a single fawn was infested with an exotic louse, which may have contributed to its death, but the ultimate cause of death is unknown. Additionally, several fawns that were killed by predators also tested positive for adenovirus in bone marrow. Therefore, it is possible that infection of adenovirus may have predisposed these animals to mortality from predation, a scenario similar to what we have observed in the Wyoming Range as well.

Fawn monitoring was lessened between the end of August and November 2016 captures because the frequency of fawn mortality is typically concentrated near birth. By November captures, 15 of the 30 fawns from Augusts were still alive, meaning we received a pulse of mortality in autumn where 15 fawns died during September and October. Overall, 73% of fawns had died by November captures. It is still unclear as to why the 2016 season produced such a high mortality rate, but we will continue to monitor these patterns in the 2017 and 2018 field seasons, and as this project continues, we will be able to disentangle important roles of predation, nutrition, and disease on fawn survival.

DeadFawns WebsiteFawns



Mule Deer and Elk Population Sizes

Mule deer have had a complex history throughout the western United States. In the days of the early settlers and pioneers, mule deer were a relatively rare species. At the beginning of the 20th century mule deer numbers were drastically reduced in number due to overharvest, market hunting, and overgrazing. Protections were placed on mule deer causing numbers to drastically increase and peak between 1940s and 1960s throughout the western US.

Present day, with a lens to examine population fluctuations over the past 40+ years, a clear pattern has emerged. Populations in Wyoming appear to go through a cycle of increase followed by sharp declines. In Wyoming, although we observe this see-saw in population numbers, there is a general declining trend in population numbers since at least the 1970s; on average, Wyoming has seen a roughly 20% reduction in population numbers across the state.  The population swings and general decline has been difficult to understand; a variety of factors have been proposed including: overharvest, harsh winters, habitat, drought, predation, and disease. A question has been raised as to why there are viable and growing elk populations while mule deer in the same systems continue to struggle. Questions arise regarding potential competition between mule deer and elk, or the conditions that have fostered growth of elk while being detrimental for deer

The complexity of these questions and the difficulty in answering them has meant that gaining a more complete understanding of the reasons for fluctuations or stagnant growth in populations has been elusive.  Without a solid understanding of the why and how associated with population fluctuations, it is incredibly difficult for targeted management to achieve desired outcomes.





Deer/Elk moving to summer ranges

As we prepare to get out and capture fawns, just wanted to leave a quick update on where animals are and what is going on.

We finished helicopter capture efforts in late April. This brings our sample size up to 51 female mule deer and 35 female elk. Shortly after captures, animals appeared to begin migrating or possibly complete migration. The reason that we are capturing so late, we typically like to capture in March, is due to somewhat abnormal migration patterns witnessed by locals for this population. We know that some animals begin fall migration in September but spring migration was a bit unknown. It is possible that some of the animals we caught spend most of the winter in neighboring states but summer in Wyoming.

All that aside, animals appear to be on summer ranges or, in some cases, as close as they can currently get with some snow on higher peaks. The maps below show mule deer and elk densities across the study area. Black lines are roads and white names are approximate labels of geographical features. Darker colors indicate higher densities.

Stay tuned for some updates once fawn captures begin!