Temporal Overlap Between Deer and Their Predators Throughout Western Nebraska

Payto Geschke Author

04/04/2021 Added

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Comparing the temporal overlap between coyotes/humans and different categories of deer.

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[00:00:00.750]Hello.
[00:00:01.230]My name is Payton Geschke and my UCARE study is titled Temporal Overlap
[00:00:04.950]Between Deer and Their Predators Throughout Western Nebraska.
[00:00:09.620]So.
[00:00:10.130]This study mainly looked at mule deer mule deer are an ecologically important
[00:00:13.880]species because they act as prey for a variety of predators.
[00:00:17.000]They're also large enough herbivores to have an influence on plant communities,
[00:00:20.690]and they are also an important hunted species.
[00:00:23.420]The mule deer population in Nebraska is highly variable with some members doing
[00:00:27.140]well. And some that are declining.
[00:00:29.390]The study wanted to examine the temporal overlap between mule deer and their
[00:00:32.600]predators.
[00:00:33.140]As it will help us to understand the behavioral patterns that may influence
[00:00:36.770]population dynamics in mule deer. When looking at a temporal pattern,
[00:00:40.790]we can see what times of day an animal is active in a certain area.
[00:00:44.210]If we see an animal showing a strong temporal pattern over a 24 hour cycle,
[00:00:47.900]this might be a behavioral technique. When looking at temporal overlap,
[00:00:51.950]we are looking at the amount of time that two variables such as deer and coyotes
[00:00:56.540]spend in the same area. We can then compare the two animals' temporal patterns.
[00:01:00.980]If there is little overlap between these two patterns,
[00:01:03.950]we can think of it as avoidance in response to the predators,
[00:01:07.370]which would hopefully reduce mortality and competition between the species.
[00:01:13.160]So we wanted to examine the amount of temporal overlap between mule deer and
[00:01:17.000]their predators. Specifically looking into coyotes and humans.
[00:01:20.630]Evaluating temporal activity of predators and prey will facilitate a better
[00:01:24.080]understanding of how prey respond to predation risk across landscapes with the
[00:01:28.400]presence of their predators.
[00:01:31.550]So our study looked at
[00:01:31.940]two different hypothesis.
[00:01:34.160]The first hypothesis we looked at is that deer will be less active during
[00:01:37.700]periods when coyotes are active,
[00:01:39.440]but that the temporal activity patterns of deer will vary by the sex, age, and
[00:01:43.490]reproductive condition of the deer.
[00:01:45.920]Our second hypothesis is that similarly to coyotes deer will be present less
[00:01:50.570]often when humans are,
[00:01:51.950]or were recently present as they likely respond equally to the risk from both
[00:01:55.790]predators.
[00:01:58.340]So I will quickly.
[00:01:59.090]go over our camera setup that allowed us to get the photos that we use for our
[00:02:01.940]analysis. As shown here, we used a grid like pattern of motion-detecting
[00:02:05.660]cameras across Southwestern, Nebraska.
[00:02:08.600]The cameras were each roughly a kilometer apart from each other.
[00:02:11.210]So they covered a fairly large area and they were active for 24 hours a day.
[00:02:14.960]For around six months. We used 20 of these cameras for the study,
[00:02:18.860]ending up with thousands of photos for analysis.
[00:02:23.450]So.
[00:02:23.930]For our first hypothesis,
[00:02:25.580]we looked at how the age, sex, and reproductive status of the deer affected the
[00:02:29.150]amount of overlap with coyotes.
[00:02:31.130]We predicted that adult deer would exhibit less overlap with coyotes than any
[00:02:34.670]younger deer, as older deer have had more experience with the coyotes.
[00:02:38.300]We also predicted that does with fawns would have even less temporal overlap
[00:02:42.590]than does without fawns.
[00:02:44.060]And we thought this because does with fawns should be more protective and
[00:02:46.910]cautious around coyotes than does without fawns.
[00:02:50.420]So the first graph is looking at the patterns across different ages and genders
[00:02:54.920]of the mule deer. We compared these patterns against the coyotes pattern,
[00:02:58.520]which is red in these graphs,
[00:03:00.670]the spikes in the graphs show high activity and the dip show low activity.
[00:03:04.780]It's interesting to see here that the only significant difference in temporal
[00:03:07.870]patterns is between the coyotes and yearlings, which are only around a year old,
[00:03:12.340]no other category of adult deer alone showed a significantly different temporal
[00:03:16.390]pattern from the coyotes.
[00:03:18.280]The second graph is comparing the patterns of does both with and without fawns
[00:03:22.600]against coyotes.
[00:03:23.950]And this interestingly shows no significant difference between either group of does.
[00:03:30.670]Our second hypothesis,
[00:03:31.800]we looked at how the age, sex, and reproductive status of the deer affected the
[00:03:35.190]amount of overlap with humans.
[00:03:37.290]We predicted that deer would react similarly to humans as they did coyotes.
[00:03:41.970]However,
[00:03:42.390]it is possible that the deer would use humans to shield from the coyotes.
[00:03:45.930]And this basically means that coyotes will be avoiding humans,
[00:03:49.320]so the deer may feel safer around the humans since they know there'll be no
[00:03:52.980]coyotes around. All right,
[00:03:55.230]so the deer are still blue and the humans are green in these graphs.
[00:03:59.280]Unlike with coyotes,
[00:04:00.270]we found a large and significant difference in temporal patterns between all
[00:04:03.630]categories of deer against the humans. And that includes the does with
[00:04:07.410]and without fawns in the second graph.
[00:04:11.160]It is also interesting to note that contrary to the human shield hypothesis
[00:04:14.430]presented earlier, the deer seem to be avoiding humans,
[00:04:17.610]even when coyotes are also avoiding humans.
[00:04:20.130]And this would reject that hypothesis, that the deer use humans as a shield.
[00:04:26.010]So.
[00:04:26.310]In our conclusions,
[00:04:27.390]our first hypothesis mainly resulted in accepting the null in almost all
[00:04:31.140]predictions.
[00:04:32.130]We didn't find any significant differences in the temporal patterns between deer
[00:04:35.700]in general and coyotes, just the yearlings.
[00:04:38.580]And we think this may be because coyotes are mainly a threat to weekend or
[00:04:41.730]injured deer. The deer we observed appeared healthy and agile,
[00:04:45.120]and this may not need to spend their time trying to avoid a temporal overlap
[00:04:48.330]with coyotes. However,
[00:04:50.010]we did find significantly less overlap between yearlings and coyotes.
[00:04:53.970]And we think that this may be because yearlings are not around the protection of
[00:04:57.870]their mother, as much as when they were younger.
[00:05:00.150]So they have to be more aware of their surroundings and any predators in the
[00:05:02.850]same space.
[00:05:04.950]Our second hypothesis showed all deer having different temporal patterns to
[00:05:09.090]humans.
[00:05:10.080]This may be because deer and humans are naturally active at different times,
[00:05:13.560]or maybe deer just view humans as more of a threat than coyotes.
[00:05:16.890]More research would need to be done to confirm that. Additionally,
[00:05:21.000]we are interested in expanding this research to look into the functional
[00:05:24.240]consequences of predation risk in terms of the trade-offs that prey make between
[00:05:28.500]foraging efficiency and safety. We hope to eventually be able to use these data
[00:05:32.910]to examine the proportion of time that deer spend being vigilant and looking for
[00:05:37.140]predators compared to the time that they spend for foraging for food.
[00:05:42.630]I would like to take this time to acknowledge and thank these organizations for
[00:05:45.840]funding my project. I could not have done it without them. And that is it.
[00:05:50.490]Thank you!

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Temporal Overlap Between Deer and Their Predators Throughout Western Nebraska

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