Evaluation of Wildlife Space Use Across a Nebraskan Agricultural Landscape

Jana Malene Author

08/04/2020 Added

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This video presentation is about research conducted to evaluate wildlife space use in agricultural landscapes by estimating the home ranges of 12 animals in central Nebraska. The research was conducted through UNL's UCARE program in the summer of 2020.

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[00:00:00.211]Hello everyone, today my poster will be
[00:00:04.313]discussing an evaluation of wildlife space
[00:00:07.054]use across a Nebraskan agricultural
[00:00:09.344]landscape.
[00:00:10.681]An animal’s home range is commonly defined
[00:00:13.451]as “the area traversed by an individual in
[00:00:16.049]its daily routines such as finding food,
[00:00:18.707]mates, caring for young and other resource
[00:00:22.679]acquirement activities".
[00:00:24.984]Knowledge of an animal’s home range allows
[00:00:28.466]for estimation of habitat selection,
[00:00:30.753]population densities, and further insights
[00:00:33.393]on space use by individuals in a region.
[00:00:38.148]As a popular source of hunting revenue in
[00:00:41.387]Nebraska, most types of landscape-level
[00:00:43.859]data on white-tailed deer is useful for
[00:00:46.751]managers regulating deer populations.
[00:00:50.001]The reclusive nature of bobcats and the
[00:00:52.376]limited amount of movement data available
[00:00:55.241]for red-tailed hawks signifies gaps
[00:00:57.638]present in our understanding of red-tailed
[00:01:00.177]hawk and bobcat home ranges. This research
[00:01:04.690]aims to analyze and compare the home range
[00:01:07.625]sizes of 12 individual animals across 3
[00:01:10.724]species through the use of Autocorrelated
[00:01:13.980]Kernel Density Estimations, also known as
[00:01:17.105]"AKDEs".
[00:01:19.301]In this study, I utilized existing spatial
[00:01:21.827]data collected in previous unrelated
[00:01:24.415]studies through Dr. Dustin Ranglack's
[00:01:26.735]lab at University of Nebraska Kearney.
[00:01:29.940]The GPS spatial data used are that of a
[00:01:32.740]bobcat 3 red-tailed hawks & 8 white-tailed
[00:01:35.306]deer located south of Kearney, NE and were
[00:01:39.085]analyzed using R and ArcGIS to determine
[00:01:43.202]wildlife home ranges. The method of
[00:01:47.250]AKDEs relaxes assumptions of independence
[00:01:52.424]& enables a greater compatibility of
[00:01:54.839]individuals with different location
[00:01:56.908]sampling schedules than standard KDEs.
[00:02:00.660]To estimate space use AKDEs account for
[00:02:03.379]the inherent autocorrelation structure of
[00:02:06.439]relocation data by fitting continuous time
[00:02:09.203]movement models. This improves accuracy in
[00:02:13.114]home range estimation over traditional
[00:02:15.466]techniques.
[00:02:18.537]Before utilizing the AKDEs I resampled the
[00:02:21.651]GPS fix rates & standardized them around
[00:02:24.500]specific time intervals through
[00:02:26.702]evaluation of the fix rate intervals
[00:02:28.789]between GPS locations
[00:02:30.459]of each animal & then grouped them
[00:02:32.896]together by species, A predefined time
[00:02:36.245]ranges known as a 'flex' was added to both
[00:02:39.038]sides of the resampled fix rate to include
[00:02:41.698]GPS locations with timestamps that don't
[00:02:44.537]quite match the resampled fix rate enough
[00:02:47.878]but still fall within the flex range of
[00:02:50.228]timestamps.
[00:02:53.155]As seen in figure 1, the map projections
[00:02:56.295]show the standardized GPS locations of 3
[00:02:59.217]animals from the study; 1 of each species.
[00:03:03.387]The purple location points are those of
[00:03:06.080]Deer 7, the orange points represent Red-
[00:03:08.812]Tailed Hawk 1 & the white points represent
[00:03:11.639]movements of the bobcat. The standardized
[00:03:15.405]fix rate of the 8 whitetailed deer was 1.5
[00:03:19.679]hours with a flex of 27 minutes.
[00:03:22.840]The standardized fix rate of the 3 red-
[00:03:25.493]tailed hawks was 1 hour with a flex of 24
[00:03:28.482]minutes, and the bibcat's standardized GPS
[00:03:31.916]fix rate was 5 hours with a flex of 120min
[00:03:36.128]These 3 tables display results of the AKDE
[00:03:43.769]the upper & lower confidence intervals of
[00:03:46.626]the estimations, & the number of GPS
[00:03:49.393]locations of each animal. The home ranges
[00:03:53.032]are given in hectares (ha) and the 95th
[00:03:55.371]percentile is considered the most accurate
[00:03:58.466]estimation.
[00:04:00.415]Note that the # of GPS locations cannot
[00:04:03.295]only be influenced by the time intervals
[00:04:05.734]between GPS fix rates, but also by the
[00:04:10.490]duration of time the animal is wearing the
[00:04:13.064]collar, as well as the possibility of the
[00:04:15.465]GPS collar malfunctioning while worn.
[00:04:20.346]In figure 2, part (a) shows small scale
[00:04:25.027]projections of the home range of Deer 7 in
[00:04:27.881]purple & the home range of Red-Tailed Hawk
[00:04:31.840]1 in orange. As you can see in part (b) of
[00:04:36.096]Figure 2, the home ranges of Deer 7 and
[00:04:39.211]Red-tailed Hawk one, which are scaled to
[00:04:41.877]size, are completely dwarfed by the home
[00:04:44.404]range of Bobcat 1, seen in blue. For ease
[00:04:47.890]of comparison to the AKDE table summaries,
[00:04:51.738]I included the ratio of hectares to
[00:04:54.542]kilometers squared, which is
[00:04:52.755]1 hectare (ha) = .01 km^2.
[00:05:02.717]The whitetailed deer exhibited the largest
[00:05:06.077]variations in home range size, and the 3
[00:05:09.432]red-tailed hawks had, on average, the
[00:05:11.820]smallest confidence intervals. Overall,
[00:05:14.423]home ranges with a smaller number of
[00:05:17.623]standardized GPS locations were shown to
[00:05:20.034]have larger confidence intervals (CI). The
[00:05:22.769]bobcat's home range was, notably, more
[00:05:26.261]than twice as large as the home ranges of
[00:05:29.010]the other 11 animals combined, further
[00:05:31.875]highlighting differences between species
[00:05:34.347]behavior, space use, & movement patterns.
[00:05:38.999]These home ranges, when paired with
[00:05:41.367]additional spatial analyses such as
[00:05:43.100]habitat resource selection, could lead to
[00:05:45.674]a stronger understanding of community-
[00:05:48.064]level space use by wildlife living in
[00:05:50.735]Nebraskan agricultural landscapes.
[00:05:55.641]I would like to acknowledge that my
[00:05:57.666]research would not have been possible
[00:05:59.431]without the support & patience shown to me
[00:06:01.960]by my advisor Dr. Andrew Little of UNL and
[00:06:04.889]by Dr. Dustin Ranglack of UNK.

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Evaluation of Wildlife Space Use Across a Nebraskan Agricultural Landscape

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