Large Mammals

mammal1

Evaluation:  See each species for individual  status

Evaluation: See each species for individual status

Issue Summary
The South Slough and coastal frontal watersheds host a variety of large mammals, including elk, deer, bear, and cougars. The Oregon Department of Fish and Wildlife (ODFW) monitors and manages these populations, dividing the state into wildlife management units for this purpose. South Slough and the coastal frontal watersheds are located within the “Sixes” unit (Figure 1). Broadly speaking, elk and bear populations appear stable in the Sixes unit, while deer and cougar populations appear to be declining slightly.

Why do we care
Large mammals are an important part of the health of the coastal ecosystem. They also hold cultural and recreational significance.

Elk

Elk

What’s happening?
Roosevelt elk (Cervus canadensis roosevelti) are one of the largest species of deer in the world. Like deer, they range in forest fringes and open riparian areas. Populations in the project area appear to be robust and stable, a trend that reflects elk populations statewide.

What’s being done?
In 1992, the Oregon Fish and Wildlife Commission set management objectives for elk in the state of Oregon, with the goal of maintaining a stable, healthy population (ODFW 2003). ODFW conducts elk inventories each year to determine the population and composition of elk herds across the state of Oregon. Biologists count bulls, cows, and calves at the end of each winter to determine the ratio of cows to bulls in each wildlife management unit. This ratio is important, because research has indicated that a minimum of 10 bulls to 100 cows is optimal for the population to reach its reproductive potential. Biologists also collect samples from harvested elk to monitor reproductive health.

Deer

Deer

Figure 1. Map indicating the “Sixes” wildlife management unit. Map courtesy ODFW

Figure 1. Map indicating the “Sixes” wildlife management unit. Map courtesy ODFW

What’s happening?
Black-tailed deer (Odocoileus hemionus columbianus), a subspecies of the mule deer, are the only deer prominent on the west coast of Oregon. A secretive, forest-dwelling animal, they are difficult to survey; as a result, most population estimates are determined by harvest reports, buck ratios, and damage reports in combination with ground surveys (ODFW 2008).

The deer population in southwest Oregon has fluctuated throughout recent history. The population declined for a period after European settlement, but stabilized once hunting restrictions were imposed. Then, in the first half of the 20th century, a series of fires known as the Tillamook Burn paved the way for lots of young, dense understory in Oregon— perfect nutrition for the black-tailed deer (Wells 2006). This disturbed habitat allowed deer to increase rapidly in both population numbers and size of individuals (Verts and Carraway 1998). Now, however, massive post-disturbance habitat is less common, leading to a slow decline in the deer population since the 1970’s. In 1979, for example, there were an estimated 452,000 deer in Oregon; in 2004, there were approximately 320,000. This decline may be a result of changes in public land management, where emphasis has shifted from open areas to managing for late successional forest conditions. Wildlife disease, such as Deer Hair Loss Syndrome, and increased predation may also have played a role in this decline. Overall, however, the deer population is now considered stable throughout the state of Oregon and in Coos County.

What’s being done?
ODFW conducts two deer surveys each year. After the close of the hunting season in the fall, biologists survey deer along established trails, attempting to count bucks, fawns, and does. Tracking the composition of the population helps biologists make population predictions for the following year. Surveys are also conducted after winter. If a fawn has made it through the winter, there is a good chance the animal will survive long enough to become a reproductive member of the population. ODFW biologists also use teeth from harvested deer to track age distribution of populations.

The Oregon Black-Tailed Deer Management Plan (ODFW 2008) lists several issues to focus on for maintaining healthy populations of deer, including: habitat availability and sustainability; causes of non-hunting mortality; encouraging interest in hunting; and preventing wildlife disease.

Why do we care?
The black-tailed deer is an important part of the culture, economy, and ecology of western Oregon. Many Oregonians hunt deer, and hunting licenses generate revenue for the state. Deer can also damage property and landscaping. Lastly, they are prey for other charismatic species in western Oregon, like cougars and bobcats.

Elk

Bear

What’s happening?
Historically there was little to no restriction on hunting black bear (Ursus americanus ) in Oregon until 1970. Since that time measures to protect black bear have included limited seasons, the prohibition of the use of dogs or bait to hunt bear, protection of females with cubs during the hunting season, and the prohibition of the sale of black bear parts. Aside from hunting, black bears may be taken if considered a threat to human safety or due to damage to livestock or forest crop. Between 2003-2008, for example, several hundred bear were killed annually in the state due to timber damage, the majority taken in Coos and Curry counties. Black bear populations in Coos County, despite some fluctuations, are now considered stable overall (Figure 2).

Figure 2. Black bear population estimates for 1999-2006.

Figure 2. Black bear population estimates for 1999-2006.

What’s being done?
Once a year, biologists nail tetracycline-laced bacon balls to trees. Two weeks later, they count the number of bacon balls taken by bears (based on scratch marks on trees). Tetracycline is a harmless dye that incorporates into the bear’s teeth allowing age to be determined in a fashion similar to tree rings. Harvest data, required for all mortalities since 2008, includes date and location of harvest, sex and age of bear, and tooth extraction to check for the tetracycline biomarker. By comparing the number of tagged bears with the number of tetracycline recovered teeth, calculations of age demographics in the population can be made (Figure 3). It is important to keep track of the ages of harvested bears because research indicates that when the mean number of bears of a certain age drops, the population is probably declining. Survival and reproduction are also monitored, based on data from radio-marked bears.

Figure 3. Ages of bears at mortality as a percentage of all bears taken during each year. Data taken from ODFW 2012

Figure 3. Ages of bears at mortality as a percentage of all bears taken during each year. Data taken from ODFW 2012

Deer

Cougar

What’s happening?
After European settlement, cougars (Puma concolor) were hunted aggressively, almost to local extinction. Bounties were given out until 1961 by which time the state bear population was down to about 200. During 1968-9 they were completely protected and their populations started to bounce back. Statewide populations have steadily increased since that time; as of 2000, the state cougar estimates were at about 4,000 animals (ODFW 2006).

From 1971-1994 controlled cougar hunting was allowed. After the passage of Measure 18 in 1994, which banned the use of hounds in cougar hunts, ODFW changed hunting regulations to an expanded 10 month season, implemented a quota system and reduced the cost of tags (ODFW 2006). Statewide, the cougar population is more robust than at any time in recent history, due in part to low hunter success rates without the use of dogs. Locally, the cougar population is considered to be declining slightly. This is possibly due to declining numbers of the black-tailed deer, which are an important cougar prey item – healthy cougar populations are directly dependent on availability and abundance of ungulates. Intestinal parasites have plagued cougars in southwest Oregon in the past, but that has not been a problem in recent years.

What’s being done?
The objective of the ODFW Cougar Management Plan (ODFW 2006) is to maintain healthy cougar populations while managing cougar conflicts with humans, pets, and livestock, and providing recreational hunting opportunities. Mandatory examination of all cougar remains allows ODFW staff to collect age, sex and reproductive data for use in population modeling.
Administrative cougar removals have occurred in areas where local hunting is not keeping populations low enough to prevent interactions with people and livestock.

Why do we care?
Cougars are highly valued as a game species, but also cause trouble by preying on livestock and pets, and, rarely, attacking humans. Elk and deer are the main food sources for cougars.

Literature Cited

BallotPedia. 2012. Oregon Bans Hunting Bears with Bait or Cougars with Dogs, Ballot Measure 18 (1994). Retrieved from: http://ballotpedia.org/wiki/index.php/Oregon_Bans_Hunting_Bears_with_Bait_or_Cougars_with_
Dogs,_Ballot_Measure_18_%281994%29

ODFW. 2003. Oregon’s Elk Management Plan. Retrieved from:
http://www.dfw.state.or.us/wildlife/management_plans/docs/ElkPlanfinal.pdf

ODFW. 2006. 2006 Oregon Cougar Management Plan. Retrieved from:
http://www.dfw.state.or.us/wildlife/cougar/cougarPLAN-Final.pdf

ODFW. 2008. Oregon Black-tailed Deer Management Plan. Retrieved from: http://www.dfw.state.or.us/wildlife/docs/Oregon_
Black-Tailed_Deer_Management_Plan.pdf

ODFW. 2012. Oregon Black Bear Management Plan. Retrieved from:
http://www.dfw.state.or.us/wildlife/management_plans/docs/Black_Bear_
Management_Plan_2012.pdf

Verts, B. J., and Leslie N. Carraway. 1998. Land mammals of Oregon. Berkeley: University of California Press.

Wells, Gail. 2006. The Tillamook Burn. Oregon History Project. Retrieved from:
http://www.ohs.org/the-oregon-history-project/narratives/the-oregon-coast/unions-and-hard-times-between-wars/tillamook-burn.cfm