Science Updates

We are currently collecting data for the first Snapshot Wisconsin Bird Edition season. We will update this page with bird-specific results when data collection is complete. Below are results from the main Snapshot Wisconsin project. Click here to access the main Snapshot Wisconsin page.

How has the data you’ve classified contributed to science? There are numerous ways that Snapshot Wisconsin data has been used to help monitor and manage Wisconsin’s wildlife populations and habitat. Below are several examples. Currently our data set contains nearly 38 million photos, and their content is a vital component of the Snapshot Wisconsin project. In the graph above, we display which species appear in our photos. Deer are by far the most common species, appearing in about two-thirds of photos, followed by squirrels, raccoons, turkey, cottontail rabbits, coyotes, and elk. The remaining 8 percent of animal tags are divided up across 34 categories. Elk may have a higher proportion of triggers than expected because Snapshot Wisconsin cameras are placed more densely in the elk reintroduction areas than in other areas of the state.

Snapshot Wisconsin Data and White-Tailed Deer Population

Wisconsin is renowned for being home to a well-established population of white-tailed deer. They are an undeniably important part of Wisconsin’s forests and farmland and are the animal that appears most frequently on Snapshot Wisconsin trail cameras. Since its inception in 2016 the project has accrued a massive supply of deer photos. This vital cache of information offers researchers the opportunity to make population-level observations about things like movement and activity patterns, and how these change with the seasons.

Out of a sample of 1.4 million Snapshot Wisconsin trail camera photos of deer, antlerless deer take the lead at 63%. The remaining 37% comprises antlered (13%), adult unknown (15%) and fawns (8%). In their ongoing analyses of these photos, scientists at the Wisconsin DNR have noted that deer show strong crepuscular patterns near both the summer and winter solstices. The word crepuscular refers to the interim between night and day, or both dawn and dusk. Deer are more active closer to sunrise and sunset than they are at any other time of day across any season. In winter, there is an observable preference toward sunset – most likely because afternoon is the warmest time of the day, and therefore the best for foraging. The opposite goes for the longer days in summer, when deer seem to prefer sunrise, as it is cooler and foraging at that time is less energetically expensive.

During the summer, antlered deer are the most likely to stick to this crepuscular pattern. On the other hand, antlerless deer and fawns are a little more unpredictable. Fawns are generally more active throughout the day, as are antlerless deer, though to a lesser extent. Antlerless deer are also more active through the night. Assuming that most antlerless deer are does, their deviation from the crepuscular pattern can be attributed to their need to move to and from spots where they drop their fawns in the time following birth. Despite their penchant for daytime activity, after the first 12 weeks fawns begin to mirror the activity of their mothers, gradually falling into the recognizable crepuscular pattern.

As for winter, both antlered and antlerless deer are seen to be most active at sunset. At this point, fawns are indistinguishable from does and are therefore not differentiated from the rest of the population in the analysis. During the winter, antlered deer are more active during the night and less active during the day than antlerless. Predictably, the annual rut drives a significant uptick in activity for male deer in late October, a pattern familiar to Wisconsin drivers who may be liable to encounter deer more frequently around the same time.

Snapshot Wisconsin’s growing cache of deer photos sheds light on deer activity as it varies through the seasons and even day-to-day. Recognizing these patterns bolsters our knowledge of how deer interact with and move through the landscape. These photos are also used to investigate population dynamics and determine fawn-to-doe ratios to better track the growth of the herd. Such a plentiful supply of information on an important species like deer is of great value to our researchers, whose analyses are a critical component of wildlife management decision-making at the Wisconsin DNR.

One of the major contributions Snapshot Wisconsin makes is providing data essential to understanding Wisconsin’s white-tailed deer population. Fawn-to-doe ratios, or FDRs, are a measure of recruitment or how many individuals are added to the population each year. FDRs are found by dividing the number of fawns by the number of does seen during the summer months. In total, three programs currently contribute to FDR estimates: Snapshot Wisconsin, Operation Deer Watch and the Summer Deer Observation Survey. An advantage of using Snapshot Wisconsin data in these estimates is Snapshot cameras tend to be placed in areas of more natural habitat, whereas the other two collection methods are opportunistic, meaning they’re biased toward counting deer seen near roadways.

One challenge associated with trail camera data is that the same individual animals may walk by the camera multiple times throughout the data collection period. To account for this, we average the total number of does seen in photos with at least one doe, and then do the same with fawns. We then take the average number of fawns and divide it by the average number of does.

2017 and 2018 Snapshot Wisconsin cameras contributing to FDR estimates

The above maps show the camera sites that contributed to FDR estimates in 2017 and in 2018. Photos from exclusively July and August were analyzed. A site only contributes to the estimate if there were 10 doe observations in one of the two months, but can be counted twice if it had at least 10 doe observations in both months. Statewide, 897 cameras contributed to 2018 FDR estimates, a 44% increase from the 622 sites that contributed in 2017.

2017 and 2018 Snapshot Wisconsin FDR estimates

Above are the results of the 2017 and 2018 FDR estimates using Snapshot Wisconsin data. Only deer management units with a minimum of 5 camera sites were included in the analysis. In 2018, the range of FDR was 0.75 – 1.2, which is an overall increase from the range of 0.62 – 1.13 in 2017. Snapshot Wisconsin was launched statewide in August 2018, meaning most cameras in the newly open counties were not deployed until after the data collection period. We expect that the number of cameras in the 2019 analysis will increase again, which would give us even more accurate estimates.

Investigating wildlife-habitat relationships

UW Madison has used Snapshot Wisconsin data, in partnership with NASA, to compare camera based observations to satellite derived measurements. UW Madison has also used Snapshot Wisconsin data to understand spatial and temporal patterns of wildlife state variables of interest. One way this has been accomplished was by evaluating spatial and temporal patterns in deer vigilance and foraging behaviors. This helped pinpoint important habitat types that have greater capacity to support deer, and to understand how inhospitable weather and predation pressure in northern Wisconsin might mechanistically interact to suppress deer abundance.

Figure 2. The prevalence of deer behaviors (conditional upon occurrence) averaged across the year

Informing Wolf Tracking Efforts

The Wisconsin DNR uses annual winter wolf tracking and territory mapping survey efforts to establish a minimum count of the number of packs and wolves in Wisconsin. Snapshot Wisconsin data of confirmed wolf observations have been used to direct tracking effort and supplement data. Confirmed locations have helped volunteer trackers focus their efforts in areas with known wolf sightings, thereby increasing survey efficiency.

Figure 3. Observed number of wolves per camera per year summarized by wolf management units. Snapshot Wisconsin camera locations (gray dots) and relative abundance (red dots) are shown with the number of camera locations in each wolf management (e.g. n=20).

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