1. RESULTS AND DISCUSSION
USE OF MITIGATED MEADOWS BY RESIDENT ELK (CERVUS ELAPHUS ROOSEVELTI) AT HAGG LAKE, WASHINGTON COUNTY, OREGON: DATA FROM 2006–2010.
Michael Garcia, Jeffrey Lee, Angela Massey, Rodney Racaza, Ryan Seiffert, Edmond Alkaslassy*, Pamela Lopez, Department of Biology, Pacific University, Forest Grove, OR,
*contact information:
Photo credits: Richard Blake and Michael Garcia
INTRODUCTION
In 1975 Scoggins Dam was constructed in Washington County, OR to create Henry Hagg Lake, which resulted in the complete loss of winter grazing meadows for local Roosevelt elk (Cervus elaphus roosevelti) herds.  Roosevelt elk foraging strategies often differ seasonally. Winter foraging strategies include lower elevation feeding, an increase in dormancy and a decrease in food intake. These strategies conserve energy during periods of decreased food availability; winter diet consists of dried grasses and twigs that are harder to digest than items in their summer diet (RMEF, 1999). Roosevelt elk need access to abundant food resources to maintain optimal health during winter months and to support reproduction, calf survival, and male antler growth (ODFW, 2002 as cited in Blakney, 2003). Prior to the construction of Scoggins Dam, landscape level disturbances such as fires and floods set back the process of natural succession in meadow habitat and allowed meadows to persist. Now human intervention (mowing, seeding, application of herbicides) maintains the meadows for winter use by Roosevelt elk. One management problem is that encroachment of surrounding vegetation, especially unpalatable species, reduces the value of winter pasture habitat for elk over time (Scotter, 1980).  
The Tualatin Project required that managed elk pastures be created to mitigate the valley floor meadow habitat lost by the construction of Scoggins Dam.  The artificial meadows, modeled after natural foraging grounds, consist of 65% grass and 35% clover. The objectives of the Tualatin Project meadow management plan were (1) to provide approximately 140 acres of high quality foraging areas for wintering elk grazing around Henry Hagg Lake, (2) to provide a method of accurately and effectively monitoring elk use of these pastures, and (3) to coordinate and report the results of the monitoring effort with the Oregon Department of Fish and Wildlife and United States Fish and Wildlife Service (USDI, 2004).
The current management plan involves the monitoring of Roosevelt elk and their use of the replacement meadows for a ten year period. The purpose of this study was to determine and compare the use of these meadows by Roosevelt elk during October through January of the 2006/7, 2007/8, 2008/9, and 2009/10 seasons.
RESULTS AND DISCUSSION
Migration Patterns: More pellet groups were collected in late November than in any other sampling period (Fig.1). After November the number of pellet groups decreased through subsequent months. According to Eggers et al. (2003), elk annually migrate down from the higher elevations to lower elevations from October through November and then migrate back to higher elevations from March to April. Food availability and snow cover may explain such seasonal movements (Eggers et al., 2003). Because no data were collected after February, we were unable to determine whether the elk utilize the meadows during other times of the year.
Meadow 1: In 2009/10 there were no pellet groups collected in Meadow 1. This was consistent with previous years (Fig. 2).
Meadow 2:  There were no pellet groups collected in Meadows 2a, 2b, and 2c in 2009/10. These results were consistent with the previous years (Fig. 2). 
Meadow 4: Unlike previous years, there were no pellet groups collected in Meadow 4 in 2009/10 (Fig. 2). The distribution of pellet groups that were collected from Meadow 4 in 2006/7, 2007/8, 2008/9, and 2009/10 was significantly different from even (χ²=32.87, P<0.05), with higher totals in 2006/7 and 2007/8 compared to 2008/9 and 2009/10. The absence of pellet groups in this meadow in 2009/10 could have been the result of large and noisy equipment associated with a nearby logging operation that began in 2009.
Meadow 5: In 2009/10 there were no pellet groups collected in Meadow 5a, with the exception of the end of November (Fig. 2). In Meadow 5b, which is the meadow with the highest total over the four years, many pellet groups were collected in 2009/10, indicating heavy use by the elk. The distribution of pellet groups that were collected from Meadow 5b in 2006/7, 2007/8, 2008/9, and 2009/10 was significantly different from even (χ²=25.09, P<0.05), with higher totals in 2008/9 and 2009/10 compared to 2006/7 and 2007/8. The distribution of pellet groups that were collected from Meadow 5b in 2008/9 and 2009/10 was also significantly different from even (χ²=8.56, P<0.05), with a higher total in 2009/10 compared to 2008/9. The large size of Meadow 5b (at 29.5 acres it is the largest of all the mitigated meadows; Eggers et al., 2003) may contribute to its consistent and heavy utilization by elk. 
Meadow 6: In Meadow 6a, moderate numbers of pellet groups were collected from late December to late January in 2009/10 (Fig. 2). In Meadow 6b, pellet groups were collected at the end of January in This is the first year that we collected data in these two meadows. Under the Elk Meadow Rehabilitation and Maintenance Plan, Meadows 6a and 6b were reseeded in fall 2009 with the Oregon Department of Fish and Wildlife’s custom seed mix; this mix is attractive to elk (Eggers et al., 2003).  
Conclusions: The distribution of all pellet groups collected in 2006/7, 2007/8, 2008/9, and 2009/10 was significantly different from even (χ²=15.73, P<0.05), with more pellet groups in 2006/7 and 2009/10 compared to 2007/8 and 2008/9 (Fig. 3). The distribution of pellet groups collected in 2008/9 and 2009/10 was also significantly different from even (χ²=6.30, P<0.05), with more pellet groups in 2009/10 than 2008/9.
Based on current and previous years, meadows on the west side of Hagg Lake (meadows 1, 2a, 2b, and 2c) have been consistently used very little, while a meadow located on the east side of the lake (5b) has been consistently used very heavily (Fig. 2). In addition, two new meadows on the east side (6a and 6b) also yielded many pellet groups. In 2009/10, the meadows located on the east side of Hagg Lake (Meadows 5 and 6) yielded the largest numbers of pellet groups. The consistently heavy use of meadows on the east side of the lake may be due to meadow characteristics such as size (5b and 6a are the two largest meadows) or orientation (east vs. west facing slopes). Another possibility is that the historic elk migration route is on the east side of the lake. N
METHODS
Nine meadows surrounding Hagg Lake were studied. Each meadow was divided into 3-6 transects. Each transect was approximately 23 meters apart from the adjacent transect and included five evenly spaced circular plots, each with an area of 9.19 m2 (100 ft2).
  Prior to the start of data collection all pellets from the previous year were removed.  
  The meadows were sampled once every two weeks from October to January in 2006/7, 2007/8, 2008/9, and 2009/10. Meadow 3 was sampled for the first time in 2008/9, and not sampled in 2009/10. Meadows 6a and 6b were sampled for the first time in 2009/10. 
  Sampling procedures conformed to those described in Smith et al. (1969).  
  An individual “pellet group” was defined as 30 or more elk pellets, in which at least half of the group was present within the plot.  
  If pellet groups were discovered in a plot, we recorded the number of pellet groups and then removed the pellets from the plot.  Additional observations regarding this study were also made, including mammal tracks, the presence of pellets outside of the plots, and signs of human activity.   
Chi-Square Tests were used to compare the distribution of pellet groups within and between years, but only in cases where the expected values were greater than five. 
Number of pellet groups
Sampling Month
Figure 3. The total number of pellet groups observed in all meadows by year for the 4 year sampling period. The distribution of pellet groups found in the 2006/07, 2007/08, 2008/09 and 2009/10 sampling periods was significantly different from even (χ²=15.73, p < 0.05). The distribution of elk pellet groups found in the 2008/09 and 2009/10 sampling periods was also significantly different from even (χ²=6.31, p < 0.05).
Figure 1. The total number of pellet groups observed each month in all meadows over the four year sampling period. The distribution of elk pellet groups found in October, November, December and January over the four sampling seasons was significantly different from even (χ²=20.52, p < 0.05).
LITERATURE CITED
Blakney, K Henry Hagg Lake Resource Management Plan. US Dept. of the
Interior. Oregon Department of Fish and Wildlife Draft. Oregon’s Elk
Management Plan, II. 52 pp.
Eggers, R. J., Eisenberg, L., and J. Boechler Elk Mitigation Meadows
Maintenance and Monitoring Plan Henry Hagg Lake, Tualatin Project, Oregon.
Rocky Mountain Elk Foundation (RMEF) “Managing Elk Habitat.”
Scotter, G.W Management of wild ungulate habitat in the western United States
and Canada: a review. Journal of Range Management 33:16-27.
Smith, R.H., Neff, D.J., and C.Y. McColloch A model for the installation and use of
a deer pellet group survey. Arizona Game and Fish Department, Special report No. 1.
U.S. Department of the Interior Bureau of Reclamation Pacific Northwest Region.  2004.
“Henry Hagg Lake Recourse Management Plan.” Appendix B.
ACKNOWLEDGMENTS
We would like to thank PUCC and Pacific University’s Natural Science Division for financial support and all the members of the elk research team at Pacific University. Washington County Parks and Recreation and the Bureau of Reclamation funded this study. Thanks also goes to Chris Wayland and Richard Blake for various forms of assistance.
Figure 2. The total number of pellet groups observed in each meadow over the four year sampling period.