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Fine-scale Movement Patterns of Coyotes (Canis latrans) on the INEEL in Idaho.

Background

Coyote depredation has been a persistent problem to the livestock industry in the intermountain west for decades. As a pest species, they can also pose problems to species other than domestic livestock, such as game and sensitive species. While current depredation mitigation programs are effective and clearly needed, a more complete understanding of how coyotes move and use space provides a more solid framework for managers to alter current techniques to increase efficiency and effectiveness. Therefore, advancing our understanding of coyote space-use and movement patterns is a crucial step in the management of this intractable predator.

Traditional methods for understanding space-use and movement patterns of coyotes (and other medium to large sized carnivores) have relied on VHF radio telemetry and quantitative techniques for home range estimation. This approach has been criticized due to the fact that home range estimation often does not examine meaningful hypotheses about an animal's movements and behavior (Kernohan et al. 2001). Recent advancements in technology now provide the means to record fine-scale location data on coyotes at a rate (e.g. every 5 minutes) and volume (e.g. 12,000 locations/coyote/sampling period) that only a few years ago were unattainable. This new approach provides a unique dataset that allows for more meaningful investigations into coyote movement patterns and the internal anatomy of their home ranges.

Objectives

The overall goal of this project is to better understand how coyotes actually move within their home ranges, paying special attention to the temporal component of the dataset. The 2004 year represents the first field season for this project, and specific goals for the year included the following:

  • Capture and radio-collar 30-40 coyotes that reside in several contiguous territories in the study area on the INEEL.
  • Test four4 new drop-off Global Positioning System (GPS) Lotek collars and analyze the data from retrieved collars to determine the appropriate sampling scheme necessary to gather meaningful fine-scale (temporal) data.
  • Using the information from objective # 2, recapture resident coyotes and deploy 16 GPS collars to gather fine-scale data.
  • Test the efficacy of new collaring scheme that increases the success of recapturing specific animals via helicopter net gunning.

Accomplishments through 2004

  • Thirty adult coyotes (16 females/14 males) were opportunistically captured during late January 2004 via helicopter and net-gun. Each coyote was processed and fitted with a 65 gram VHF radio collar. Two pairs of coyotes from adjacent packs were also fitted with a GPS collars set to record locations every 5 minutes. Figure 9-3 shows the distribution of territories monitored during the 2004 season.  (See Capture Technique)
  • The testing of the GPS collars showed exceptional accuracy (avg. error < 25 meters) and performance with an average acquisition success in the high 90th percent. Most missing locations were preceded and followed by accurate locations very near den sites, suggesting that the animals were underground and out of satellite view.
  • Given the roughly inverse relationship between the absolute number of locations and the sampling interval of the collars, the data were sub-sampled to determine which interval provided the best data set for future sampling periods. It was concluded that although collecting locations every 5 minutes utilizes battery life rather-quickly, it also provides the most accurate and useful data for the question of interest (i.e. fine-scale space-use and movements). Even the most conservative re-sample (i.e. every 10 minutes) frequently resulted in interactions between coyotes and re-visitation to point locations being missed. Figure 9-4 shows the difference in total straight-line distance traveled for a single coyote at different sampling intervals during a single sampling period. Figure 9-5 shows an example of how different sampling intervals change the shape of an individual's movement path.
  • The use of two separate collars (one VHF and GPS) is a rather new approach to monitoring wildlife species. The idea is to keep radio contact with animals after the GPS collars drop-off, and to increase the probability and efficiency of recapturing specific coyotes multiple times by homing in on the VHF frequencies with the helicopter during capture. The second capture in early December 2004 showed the success of such an approach. With 16 GPS collars available for deployment, 12 collared animals were able to be recaptured. GPS only had to be deployed on four unknown animals (three of which proved to be pack associates of previously collared animals).

Results

The project is still in the data collection phase, although a few preliminary results have been provided below for those interested.

  • Home ranges for coyotes on the INEEL site appear to be relatively large compared to previous studies. While this trend is true for most territories monitored, one pair of elderly coyotes (approximately 10 years old) appear to be an exception with their comparatively small home range (see Figure 9-3).
  • Using serial locations to examine coyote movement patterns allows one to visualize how coyotes actually travel within their home ranges. Figure 9-6 shows the 5-minute GPS data (approximately 12,000 locations) and travel paths superimposed on the home range for a single coyote. A computer algorithm was used to divide locations into either "stationary" or "moving." This allows us to group locations into unique continuous "movement paths" and "resting spots" for further analyses (Figure 9-7).

Plans for Continuation

  • Two additional captures are scheduled for 2005 (Spring and Fall/Winter) with plans to deploy between 16 and 24 GPS collars during each period. This should generate roughly 500,000 coyote locations.

Investigators and Affiliations

Mike Ebinger, graduate student, Department of Forestry, Range, and Wildlife Science, Utah State University, Logan, UT

Mike Jaeger, Research Zoologist, USDA/APHIS/WS/National Wildlife Research Center, Predator Ecology Field Station, Logan, UT.

Funding Sources

USDA/APHIS/WS/National Wildlife Research Center, Ft. Collins, Colorado.

 

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