STUDY AREA AND STUDY POPULATION

Antelope Creek (50.66°N, 108.27°W at center) is a 258 km² area in rural southern Saskatchewan, Canada. The north boundary adjoins the South Saskatchewan River and is characterized by several creek valleys that create a network of coulees, ravines and draws of natural vegetation surrounded by agricultural land that extends to the south (Acton et al., 1998).

The most common habitat is crop (46.6%), followed by grassland (35.6%), shrub (7.8%), mixed grassland and shrub (7.6%), woodland (2%) and open water (0.3%).

This study area is located within the mixed grassland ecoregion which is characterized by a semiarid climate (Acton et al., 1998) with mean extreme minimum and maximum temperatures of -34.16°C and 35.1°C, respectively (Government of Canada, 2014). Its soil is predominantly clay and clay loam (College of Agriculture, 1923). This area has a variety of grasses, forbs, shrubs, annual crops and perennial forage crops (see Table 2-1). Very little forest is present, with only small patches of creeping juniper (Juniperus horizontalis), chokecherry (Prunus

virginiana), and prickly rose (Rosa acicularis) (Thompson and Hansen, 2001; Silbernagel, 2010). The prevailing type of agriculture is grain farming (Saskatchewan Ministry of

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Agriculture, 2012). Mixed farming practices, with diversification of crops and the keeping of livestock, have been in place for several decades in this area (College of Agriculture, 1923).

Table 2-1. Common and scientific names of common plants in Antelope Creek.

Grasses

Wheatgrass Agropyron spp

Needle-and-thread Stipa comata Blue grama grass Bouteloua gracilis

June grass Koelaria macrantha

Forbs

Pasture sage Artemisia frigida

Moss phlox Phlox hoodii

Shrubs

Snowberry Symphoricarpos

Wolf willow Eleagnus commutata Annual crops

Barley Hordeum vulgare

Durum wheat Triticum durum

Wheat Triticum spp

The population of free ranging Rocky Mountain mule deer (Odocoileus hemionus

hemionus) in the study area was estimated to range from 322 to 422 mule deer in 2007 and 2009 (unpublished data), and was mostly (67% of adults) non-migratory (Skelton, 2010). Their

predominant predators are coyotes (Canis latrans) and humans (Homo sapiens sapiens), as black bears (Ursus americanus) and gray wolves (Canis lupus) have been extirpated from the area.

Rocky Mountain mule deer and white-tailed deer (Odocoileus virginianus) have been recognized as infected with chronic wasting disease (CWD) in this area since 2002, and Antelope Creek is part of wildlife management zone 13. Efforts to control the spread of CWD among free-ranging cervids have included culling and preclusion of cervid translocation (Alberta Prion Research Institute et al., 2011). Despite these efforts, the prevalence of CWD in adult mule deer increased from 0.98% (20/2046) in 2004 to 6.5% (16/246) in 2009 (unpublished data).

30 2.2 CAPTURE

For this study, we captured ≥ 8 month old deer at various years using a helicopter and net-gun (Webb et al., 2008), or less frequently, Clover traps (Clover, 1954) (Table 2-2). Upon capture, we chemically immobilized them with an intramuscular injection of tiletamine-zolazepam (Telazol®, Zoetis) and xylazine (Rompum®, Bayer) at 2:1 ratio = 3 to 4 mg/kg of tiletamine-zolazepam at a concentration of 258 mg/ml + 1.5 to 2 mg/kg of xylazine. Fawns were hand captured at birth as part of a concurrent study (for details, see Perera, 2012) (see Table 3-1 as well).

Table 2-2. Annual numbers of ≥ 8 month old mule deer captured with helicopter and net-gun or Clover traps in Antelope Creek.

Capture

year Capture dates Helicopter Trap

Total captured New Recaptured New Recaptured

2007 March 13 and 14, May 9 52 52

2008 March 24, April 9 and 12 7 7

2009 January 20 to March 9 31 8 26 3 68

2010 February 19 to 25 63 44 107

2011 March 19 to 23 65 40 105

2012 March 20 to 23 41 41

Total 211 133 33 3 380

All these deer were captured and fitted with a new collar. Some deer were captured and collars were removed without replacement (3 in 2009, 1 in 2010, 13 in 2011, and 27 in 2012), but those are not included in this table. Helicopter = deer captured using helicopter and net-gun, Trap = deer captured using a Clover trap, New = deer captured for the first time, Recaptured = deer that were previously captured.

We took samples of saliva, feces, hair, and blood from each captured deer. We recorded body measurements, weight, sex, and age (based on the eruption and wear patterns of mandibular

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teeth (Jensen, 1996). We also took biopsies of ear auricle for genetic analyses, and of tonsils and in some cases rectal mucosa (only taken from males and non-pregnant females) for CWD

diagnosis.

Each individual was ear-tagged and fitted with a radio collar. We tagged one ear with a metallic yellow ear tag with a unique number (Kurl-lock #2 metal tags by Ketchum, Ontario, Canada), and the other ear with a plastic ear tag with a unique number-color combination and a contact phone number (Reyflex tags by Ketchum, Ontario, Canada). Also, on each radio-collar we attached two or four plastic tags (Ritchey Livestock ID, Colorado, USA) creating a unique color-position combination for each deer (Figure 2-1). We used both GPS (global positioning system) and VHF (very high frequency) radio-collars during the study (Table 2-3 and Table 2-4).

GPS collars included models 7000, 4400 and 3300 (Lotek Wireless, Ontario, Canada), and were mostly programmed to automatically take fixes every two hours (with a few deer equipped for fixes every 1 or every 4 hours). The GPS collars also had a VHF transmitter (also called VHF beacon) for directly tracking animals but it was turned off during the night to extend the battery life. When the collar has not moved for 8 hours, a switch is activated causing the VHF signal to be heard in the receiver at a markedly increased speed, or pulse rate, than a “live” signal. The collars did not have programed or remotely activated drop-off features so we needed to plan on re-capturing collared deer before the end of the batteries lifetimes (both main battery and VHF beacon battery). The GPS 4400 and 7000 collars are equipped with UHF (ultrahigh frequency), so the data could be downloaded remotely while the collar was still on the deer. The GPS 3300 stored all the data on board for the duration of deployment and data was collected at the end of the use of the collar. The VHF (Lotek Wireless, Ontario, Canada) collars need to be located directly using an antenna and receiver either on foot or by aircraft or by other vehicles appropriately equipped. These collars also transmitted a mortality signal after remaining

motionless for 8 h. Yearlings (8 to 21 months old) were fitted with a VHF collar (except in very few cases in 2007) and adults (>21 months old) were fitted with either a GPS or a VHF collar.

VHF collars were either expandable (with an elastic band) or rigid and not expandable, while GPS collars were all rigid and not expandable. We added an insert made of foam encased in strong fabric to rigid collars for males to allow for neck growth during the rut. When a mortality signal was heard during tracking, the location was recorded and then the collar and/or carcass were located as soon as possible.

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This female mule deer was uniquely identified based on the type of radio-telemetry collar (GPS 7000), the position and color of the plastic tags attached to the collar (white – dark blue), the color of the ear tag (light green), and the unique radio-frequency.

After sampling, tagging and collaring each captured deer, we chemically reversed the anesthesia with an intramuscular injection of atipamezole (Antisedan®, Pfizer; 1 mg of atipamezole per 8-12 mg of zylazine used). Deer were released as close to the capture point as possible. We intensively monitored collar signaling for two weeks after capture to detect early mortalities or movements outside the study area. We did a post-mortem examination to

determine cause of death.