Deer and elk are wildlife that many members of the public, but especially hunters and, many wildlife biologists think of when they see early seral forest habitat. Deer and elk are icons of ESF. They are icons because of their important role in the history of this country. This morning I’m going to discuss a little bit of history of deer and elk in OR the relationship of deer and elk with ESF habitat, why it is important to them and if the attributes of ESF that benefit deer and elk also benefit other wildlife species.
Early settlers in OR reported deer to be abundant in the early 1800’s, but their numbers began to decline Dwindling numbers of deer resulted in buck hunting laws, creation of refuges and areas closed to hunting. By 1930’s mule deer densities resulted in over-utilization of their range. Populations increased as a result of hunting regulations, refuges and predator control. By 1940’s herd control measures – predominantly antlerless hunting were instituted. Series of severe winters in the 1980’s thought to be responsible for a significant decline prompting winter feeding.
Elk too were plentiful when early explorers and settlers arrived in Oregon. But market hunting devastated most herds throughout the state. Market hunting was banned in 1905 and re-introductions, primarily from Jackson WY began in 1911. It was not until 1933 that hunting was authorized and by the late 30’s damage complaints in eastern OR began. In the 1970’s there were a significant number of transplants of Roosevelt Elk in western OR.
Deer and elk are considered habitat generalists: they can occupy a wide range of habitat types. However, deer and elk populations reach highest densities when their range includes a substantial proportion of early seral forests. Deer are more specialized in their food habits than elk, but neither deer or elk are dependant upon early seral forests. There is considerable documentation of declining populations of deer and elk as ESF matures into closed canopy condition.
The Tillamook burn is a good example of the high densities deer can achieve in ESF The Tillamook Burn in western OR, which was actually a series of 3 burns 1933, 1939 and 1945 that covered well over 300,000 acres in NW OR. You can see in this photo how devastating the fire was. A study began in the 1950’s on the Cedar Creek watershed in the burn which enclosed one-half of a square mile provided very important information on BTD population dynamics, and food preferences in ESF. The population of deer actually reached 109 deer per square mile in the enclosure and averaged 62 deer per mile for 5 years which was the length of the study. Old timers till talk about the deer population that developed after the burn.
What is early seral forest habitat for wildlife? I suppose wildlife biologists could define early seral forest habitat differently than foresters and differently for different wildlife species. For deer and elk, early seral forest habitat is primarily a source of food, some cover, a place to have their young or grow their antlers and so on. Within this habitat there will also be important micro-habitats and climates. There are also differences in quality and quantity of food and cover for deer and elk within early seral forest habitat, which I will discuss later. In this talk for simplicity sake we will define early seral habitat as post disturbance to closed canopy forest with little or no understory.
There are physiological differences and similarities between deer and elk that are important to note to help understand their use of ESF The ratio of the volume of the deer’s rumen to their body mass is relatively small. As a result, microbial digestion of the vegetation in their rumen has less time to occur than other ruminants with a larger ratio. The end result is that deer need a high quality diet: nutritious and easily digestible. The greater the cellulose of cell walls and crude fiber the less breakdown will occur. Deer forage quickly then ruminate in cover to digest their food. In winter, their forage intake decreases as an adaptation to energy conservation during scarce food supply. They are less active and burn fewer calories in winter. To survive a winter they must put on considerable fat supply during the growing season. The most critical time for a deer is the beginning of the growing season when their fat reserves are at the lowest level, yet their energy demands are growing. Late winter storms that cover forage at this time create the largest die-offs.
An elk has a much larger rumen volume to body mass ratio than other North American cervids. Elk are more similar to cattle. Because of this large ratio, an elk is more capable of digesting plants with higher cellulose content . In other words an elk can survive on a less digestible diet relative to deer as long as there is enough quantity. I’ve heard it commented before that an elk can eat anything a deer can eat, plus 50% more. Their eating pattern is similar to deer: they eat quickly and spend a large part of their time ruminating. Because their social structure tends to form groups, their predator defense mechanisms are different than deer and they may select areas to ruminate that can be considerably different than deer. Elk may often ruminate in ESF with little cover. Elk also lose weight during winter months, but as their metabolic rate slows they burn less calories in winter. As with deer, elk must gain weight and body fat during the growing season to survive winter.
In a short summary, the quality of forage is important of both deer and elk - more so for deer. The quality of forage depends upon crude protein levels which are typically highest during the growing season, and digestible energy. Crude fiber negatively affects digestibility and crude fiber increase in winter. Dry matter, on the other hand, affects the quantity of nutrients available for digestion. Dry matter is lowest during the growing season and highest during winter. Typically plants are more nutritious and digestible during the spring and summer, but some species show little seasonal differences.
So what does the dietary needs of deer and elk mean in relation to ESF? Because of their need for a high quality diet, plant species diversity is very important to deer. Browse is their primary food. It may seem that browse would not be of high quality; however leaders and leaves of woody plants, especially those that are not dormant can be highly digestible. Some browse species such as the native trailing blackberry do not dramatically change in crude fiber content between summer and winter and are highly nutritious even in winter. As you would expect, deer seek plants that are actively growing and seasonal differences can be profound.
This is a list of some of the plants documented to be preferred by btd in various seasons. Studies on their use and preferences indicate that deer prefer green leafage in all seasons. Evergreen and semi-evergreen shrubs that retain leaves in winter are consumed. In winter, grasses can become a large part of the diet of btd if the grasses are not dormant. Forbs are predominantly used during the growing season unless they maintain leaves during winter.
Much the same can be said about mule deer. Their diet varies seasonally. Grasses may play more of a role compared with BTD. Some of the species they use include…
Elk will also vary their diet seasonally, but they do prefer grasses over shrubs when both are present. When grasses are greening-up and highly digestible, elk will use them heavily. As grasses mature, elk will move onto forbs and shrubs that are actively growing. As grasses mature elk are more likely to forage on them than deer.
There are some pitfalls in assuming you can judge the quality of ESF by estimating deer and elk densities that use them. There are confounding factors to habitat use and it should not be used to judge habitat quality without a thorugh investigation. I can give you two examples in the mid-coast of OR BTD populations near the Siletz River. In the early 1990’s several thousand acres of a 40-50 year old stand of industrial forest land were harvested in a mosaic near the lower Siletz River. Prior to the harvest we did not observe deer or find much sign that any substantial population of deer existed, the canopy closure had created an understory virtually devoid of vegetation. For several years after harvest we rarely saw any deer during our surveys. I believe that contrary to the idea the ESF was of poor quality (which it may well have been), deer density did not increase because there did not exist a source population that could expand and occupy the habitat. Elk populations in Lincoln and Benton Counties were limited in size and distribution beofre transplants in the 1970’s. The rapid expansion of elk numbers in these counties may not indicate the quality of the ESF was high, but that the elk were entering unoccupied habitat that allowed for rapid expansion.
Bewicks wren prefer ESF, they are cavity nesters that feed primarily on insects and spiders. They do not typically occur in arid deserts nor moist dense forest. Mt. Quail prefer open forested habitats, meadows, riparian areas each with considerable shrub component. They appear to thrive in ESF habitat. They are ground nesters and require concealment cover. In addition, they eat buds, flowers, leaves and bulbs in spring and summer (some insects and berries as well). In winter, seeds comprise a large portion of their diet. Mt Quail have declined significantly in the last few decades especially in the northern forest and intermountain ecoregions. Habitat loss is suspected as a primary cause. In a sense, I think they are a more valuable indicator species of ESF quality and quantity than mule deer.
Not all reptiles prefer the open, sunny habitat of ESF, but many do. The western fence lizard is a good example. They prefer arid conditions and are not found in humid, dense forests. One aspect they do require is vertical structure such as logs rock piles, snags. The northern alligator lizard however prefers humid areas within ESF. The ranges of both species does overlap in western Oregon, but they have significantly different microclimate requirements.
Many species of snakes utilize ESF, this bull snake is found in many habitats including ESF. By comparison, a rubber boa will use ESF habitat and can be quite common in ESF that contains downed logs and stumps in advanced decay.
Amphibians are limited in mobility with highly specialized requirements for Ta, relative humidity, soils, physical and biotic structure and are for the most part predators of invertebrates. The microhabitats and microclimate within ESF are very important to amphibians. Clouded salamanders are primarily forest dwellers that can be commonly found in ESF that have large downed logs. They typically forage on ants and termites. The Great Basin Spadefoot and Western Toad use a variety of habitats that includes esf, but they need water to breed (temporary or permanent for spadefoots) and both eat insects. Western Toads are in decline, but the reasons are unknown.
A wide variety of mammals occupy ESF habitats, some of which are highly specialized. The Pacific shrew eats snails, slugs larvae and requires downed logs, brushy thickets and/or ground debris such as leaf litter. The white-footed vole, which appears to be an ESF habitat obligate, may be benefiting from timber harvest. It is a very rare mammal once found in the typical ESF habitat shown here in the Coast Range of Oregon: a small opening created by wind throw in the Spruce zone. The white-footed vole is a leaf eater: of shrubs, forbs and will also consume roots The western harvest mouse on the other hand prefers grassy areas in ESF and is primarily a seed eater. In summary, mammals, birds reptiles and amphibians, many have specialized needs that are not required of deer and elk.
A couple of years ago I gave a talk on ESF habitat on “big game and ESF”. At that talk I did discuss attributes of ESF and black bears. But in the mid-coast of OR we spend a great deal of time working with bears and have come to realize they can live anywhere and eat anything, including baby diapers, It is pointless to talk about them in this context.
Quality ESF, especially for deer, provides a diverse plant community that is high in digestible energy, protein and is available year-round. It also it is in a landscape that provides other habitats that provide cover from weather and predators including people. Quality ESF habitat for deer will provide benefits for other ESF species. I think if you looked at ESF and thought, ”that area would be full of deer, you probably would also think other species would benefit as well. Conversely, a ESF that provides little benefit to deer, one with little plant diversity, such as an intensively managed post disturbance plantation, it would have limited benefit to only a few wildlife species. Because many ESF species require additional physical structures and biotic attributes than deer and elk do, landscape management should not be specifically designed for deer or elk unless the goal is single species management. Currently, it appears that federal lands provide quality early seral forest habitats that is in low quantity. Conversely, early seral habitats on industrial forest lands are abundant, but are of low quality.
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