Can woodland caribou and the forest industry coexist : The Ontario scene

Ontario is in the process of developing a strategy to improve the likelihood of woodland caribou (Rangifer tarandus caribou) and the forest industry coexisting in the province. This strategy is described within a set of proposed Timber Management Guidelines for the Provision of Woodland Caribou Habitat. The proposed guidelines advocate managing for large blocks of suitable winter habitat across caribou range, large cutovers to regenerate caribou winter habitat and the protection of traditional calving areas and travel routes. Summer habitat wil l be provided by the resulting mosaic. The forest industry can provide a sustainable supply of woodland caribou habitat that was traditionally maintained by wildfire.


Introduction
Woodland caribou (Rangifer tarandus caribou) range in Ontario has receded northward since the late 1800's, probably as a result of a combination of factors including hunting, fire, land clearing, logging, increased predation by wolves (Cants lupus) due to increased densities of moose (Alces alces) and deer (Odocoileus virginianus), disease caused by brain worm (Parelaphostrongylus tenuis) and human disturbance (Darby et al. 1989).At present, the southern boundary of the zone of continuous distribution of woodland caribou in Ontario is approximated by the northern limit of large-scale timber management.
Ontario has made a commitment not to let any species decline provincially as a result of timber management activities.At the same time it recognizes the economic and social importance of the timber industry to well-being of the citizens of the province.As a result, Ontario has embarked on developing a set of guidelines that will enable the forest industry to coexist with woodland caribou.This report describes, in general terms, the principles behind the proposed Timber Management Guidelines for the Provision of Woodland Caribou Habitat.It describes aspects of summer and winter biology which are considered significant for woodland caribou living in areas subject to timber management.In addition, it describes general concepts for timber management within woodland caribou range and explains the rationale for why we believe caribou and the forest industry can coexist.

Habitat requirements
Forest-dwelling caribou are found over most of Ontario's woodland caribou range.They are essentially solitary from just prior to calving in May until just prior to the rut in late September.They form small groups during and after the rut until late April.Maximum group size seldom exceeds 50 animals, and usually averages less than 10 throughout the September to April period.Average group size from May to September is less than two animals.(Mohr 1947;Jones and Sherman 1983).This does not account for overlapping individual ranges.
^ Note additional studies are necessary over time to determine factors affecting range size utilization.
Generally, conifer stands are not useful as winter habitat until 40 years of age when stand density decreases and terrestrial lichens become abundant.Stands between 40 and 100 years of age may provide satisfactory lichen supplies when canopy closure is 70% or less.By about 100 years, their usefulness begins to diminish due to declining lichen productivity and the in-creasing prevalence of bryophytes like feathermosses (Ahti and Hepburn, 1967;Miller, 1976;Bergerud, 1989a).At this stage, fire and logging can serve to regenerate lichen supplies (Ahti and Hepburn, 1967;Miller, 1976).However, the standing crop and species composition of the lichens appear to be more related to differences in humidity, soil texture and depth, tree canopy, slope, drainage, aspect and past use by caribou than to stand age (Miller, 1976).
The amount of area occupied by woodland caribou in winter depends on the number of animals in a herd, forage availability and quality, snow conditions and predators.Studies of woodland caribou occupying boreal forest yearround show that individual caribou may occupy 32 to 784 km 2 in winter, 250 km 2 on average (Table 1).However, mean monthly group size in winter varies from 2.8 to 11.4 (Shoesmith and Storey, 1977;Fuller and Keith, 1981;Darby and Pruitt, 1984;Brown et al. 1986;Cumming and Beange, 1987;Bergerud 1989a).The wintering areas occupied by individual caribou in these groups are largely overlapping.Consequently, the wintering area of a population or "herd" of caribou needs to be considered for the purpose of managing habitat.
Table 2 shows the size of wintering areas reported for various herds of woodland caribou occupying boreal forest year-round in or adjacent to Ontario.The mean wintering area required per caribou on a "herd" basis is 16.1 km 2 .Behaviour may vary but the main factors affecting area occupied in winter are forage availability and quality, snow conditions and predators.For example, some caribou make long distance movements in mid-winter (Fuller and Keith, 1981;Edmonds and Bloomfield, 1984), sometimes in response to deep snow (Brown et ai, 1986) or to predators (Bergerud, 1989b).
Calving/summer habitat Information from marked cows (Shoesmith and Story, 1977;Fuller and Keith, 1981;Brown et ai, 1986) indicates that individual forest-dwelling, cow caribou exhibit inter-year fidelity to certain geographic locations, including both calving sites and summer ranges.
Calving generally occurs at sites where security from predation is maximized (Bergerud and Page, 1989).For forest-dwelling caribou, these areas include islands in lakes, lake shorelines (especially those with rutted topography and/or peninsulas), and isolated or secluded islands in bogs and fens (Bergerud, 1974;Shoesmith and Storey, 1977;Darby and Pruitt, 1984;Brown et ai, 1986).
Caribou that occupy islands or shorelines often represent those forest-dwelling caribou with the greatest degree of cohesive behaviour and visibility during calving.This permits some "herd" identification and has led to a preponderance of data on island and shoreline calving locations resulting in an emphasis on their management.Although justification for this is linked to visibility and the amount of data available, in most documented cases it is clear these locations are used annually by significant local or regional groups of caribou.
In contrast, mainland calving sites may represent the calving habitat of more dispersed cows.Identification of a "herd" or even association with a specific wintering area is difficult.Widely dispersed calving sites in isolated or secluded bogs, fens or in mainland forest stands are more difficult to identify, and less likely to attract human attention.This has resulted in the collection of little information, and a lack of emphasis on their management.However, a much higher proportion of Ontario's caribou may give birth to calves in this type of site and collectively they may be more important than islands or lake shorelines.
Summer home range is generally the smallest seasonal home range for both sexes, compared to fall and winter.Females with calves often move back and forth to the mainland in July and August (V.Crichton, Manitoba Dept.Nat.Resources, pers. comm. 1990).Much of their activity occurs within 100 m of shore, possibly  because of the potential for escape to water when predators threaten.There is a significant risk of predation of calves and adult females at this time of year (Shoesmith and Storey, 1977).
Island and shoreline habitats may also providesome relief from insects.Caribou seek rapidly growing green plants in spring and summer, and their diet is probably most varied during this period.

Forest management practices compatible with woodland caribou
Timber Management Guidelines for the Provision of Woodland Caribou Habitat are currently under development in Ontario.Details have not yet been finalized.However, the general principles which may be supported biologically, are described in the following text.
One of the primary, non-economic objectives of timber management activities in woodland caribou range is to ensure a sustainable mosaic of year-round caribou habitat.To achieve this, caribou habitat must be managed on a very large temporal and spatial scale, often spanning more han 1.000 km 2 , and more than 60 years.Timber management may be planned to partially replace the renewal role that wild fire has played in the past.This strategy would see large blocks of land, usually exceeding 100 km 2 , and containing winter habitat, set aside until other winter habitat blocks become available nearby in the mosaic.This in turn would require large blocks of timber to be allocated for harvest so they could regenerate to provide suitable winter habitat approximately 40 years in the future.Although the clearcut harvest system would be expected to be employed, it would not necessarily mean the harvest blocks would be cut clear.
Regeneration objectives on dry to very dry, sandy or shallow soils should be to reestablish jack pine or black spruce stands with 50-70 percent crown closure at maturity, and with relatively few deciduous trees or tall shrubs.These soils include Northwestern Ontario Forest Ecosystem Classification (NWO FEC) soil types SI, S2, and SSI to SS5 (Sims et ai, 1989).Treatment options that encourage lichen regeneration should be used where possible.
Access should be restricted in areas of existing or potential high quality winter habitat by making roads of a temporary nature.This means that the primary road network should be devel-oped around and not through existing or potential high quality winter habitat.Winter roads may provide suitable access to winter habitat blocks during harvest.
Potential calving areas such as lakes with long irregular shorelines or islands, or open bogs and muskegs with dry hummocks or islands should be protected with a no-cut reserve.Where the sites are known to support caribou calving, the size and shape of the reserve may vary to suit the site.Small scale manipulation of the reserve may be desirable to provide a continuous supply of summer food for the cow calf group.
Timber management operations should be planned to avoid creating a barrier between calving areas and associated winter habitat.This could be done by either scheduling harvest to provide continuity of habitat between the two areas, or by leaving a 2 km wide travel corridor to traverse otherwise large cutovers or young reforested areas.Known migration routes should be protected in a similar way.Mineral licks should be protected by a no-cut buffer.

Rationale for forest management practices compatible with woodland caribou
Caribou and moose have different winter habitat requirements.Caribou prefer large expanses of mature lichen-rich coniferous forest and do not use woody browse as a dietary staple.Moose prefer an interspersion of mature and early successional mixedwood stands that provide woody browse close to cover.Where caribou and moose overlap, high wolf densities supported by moose populations are likely to cause a reduction in caribou numbers.Thus, management for caribou and moose habitat on the same land base is counter-productive for caribou.
Sustaining the supply of caribou habitat is essential to maintaining caribou numbers.Management of access is equally important.Access development is a major contributor to increased mortality of caribou due to increased predator access, human harvest, road kills, and altered habitat use and suitability.

Habitat mosaic
The boreal forest has primarily been shaped by wildfire.The present abundance of old forest stands in the northern extremity of the commercial forest in Ontario is primarily due to the suppression of fire.
Fire size in the boreal forest is variable, with fires ranging in size from 0.1 ha to 1,000,000 ha.In northwestern Ontario, large wildfires are common (Table 3), with Ministry of Natural Resources (MNR) administrative districts of Red Lake, Sioux Lookout and Geraldton averaging at least one fire greater than 100 km 2 per year since 1976.If the present intensity of fire suppression persists, renewal of forest stands by timber management provides the best opportunity to sustain a supply of stands suitable for caribou winter habitat.
The purpose of creating a habitat mosaic is to ensure a sustainable supply of habitat.As younger stands with the attributes of desirable winter habitat become available, older winter habitat blocks may be allocated for harvest.Establishment of a sustainable mosaic of caribou winter and summer habitat will require long term, and large scale planning.
Caribou have behavioural adaptations for predator avoidance which manifest themselves in calving and winter habitat selection.Large areas of mature coniferous forest, particularly lichenrich open jack pine or black spruce stands, are desirable winter habitat because they have an abundant winter food supply, a relatively low suitability for moose, and thus relatively low populations of wolves.
Any alterations to the habitat that encourage an increase in prey species for wolves within range quality is enhanced by patterns of timber harvest that produce abundant browse and edge.This is inappropriate in areas being managed for caribou.
There is an abundance of mature and overmature forest within existing caribou range.A sustainable mosaic of caribou habitat will require at least som large areas of land containing stands of each major age class.This condition cannot be realized within the first rotation of  20; 20-40; 40-60; 60-80; and 80-100.Habitat and access planning on a temporal scale of 60¬ 100 years may be required to achieve this habitat mosaic.
In addition to access planning, fire planning may also be necessary.Timber management may reduce the inventory of mature stands suitable for caribou habitat to the level where losses to fire are less acceptable.Winter habitat blocks consisting of mature or overmature timber will have to be made a priority for fire suppression because both timber supply and caribou habitat are at risk.
Much of the rationale for managing habitat in caribou range is based on the premise that management for caribou and moose on the same land base will not benefit woodland caribou.At this time, almost all the productive forest lands in north western Ontario are managed for moose by applying the Timber Management Guidelines for the Provision of Moose Habitat (OMNR, 1988).Guidelines for moose habitat limit the size of cutovers to increase edge and provide cover and food in close proximity.
Woodland caribou take longer to reach sexual maturity than either deer or moose and do not have multiple births (Darby et al, 1989).This low reproductive potential may be a life history adaptation which allows them to occupy the tundra and mature boreal forest niche.Preda¬ tion and loss of mature coniferous forest are serious threats to Ontario caribou, especially where moose, deer, and wolf numbers increase to relatively high levels in caribou range after logging.Access provided by forestry operations can increase losses to predators, poachers, native hunters and vehicle collisions.A recent Alberta study, for example, showed 70% of mortality in winter range was human related along access routes (Edmonds, 1986).
The curious and often unwary nature of caribou, coupled with seasonal gregarious behaviour make caribou especially vulnerable to hun-ters and poachers where roads have accessed their range.Careful road planning to minimize access-related disturbance is an essential component of caribou habitat management.
Caribou are probably most sensitive to disturbance, including human activity, during the calving period (Bergerud, 1974;Klein, 1979;Valkenburg and Davis, 1986).Reaction to and avoidance of human-made obstructions such as roads differs between open habitats and forest habitats, and caribou appear more sensitive in the latter.Actual vehicular traffic may be a greater deterrent than the road alone.
Distribution of calving cows was altered by construction and use of a road system in Alaska (Dau and Cameron, 1986).Roads and human activity should be discouraged within about 1.5 km of calving areas.

Predator relationships
Forest dwelling caribou disperse or space themselves to avoid predators.The success of this predator avoidance strategy depends on the distance that they can space themselves from predators and alternate prey.When logging takes place it reduces the available space for caribou, thereby increasing caribou densities elsewhere and forfeiting the advantage of space (Bergerud and Page, 1989;Bergerud, 1989a) Forest fires also reduce space in the short term, but renew caribou habitat in the long term.Caribou have evolved to shift their range in response to fire and can likely shift it in response to logging.However, a given amount of cutting in different patterns can affect caribou differently.A pattern of small dispersed cuts likely increases edge, moose and deer density and over time, wolf and bear density.It also intersperses predators with caribou, increases number and length of roads and likely increases mortality of caribou.When logging and road access are concentrated in a single large cut, these negative effects on caribou are minimized.
Protection of calving habitat is particularly important for woodland caribou.The close association of calving and summer range, the risk of predation on productive components of the population, and the satsifaction of other habitat requirements (e.g.insect relief and food) are other strong arguments in favour of protection of identified areas of calving.Design of such ha-bitat protection should minimize the likelihood of increased predation.For example, protecting a strip of forest that is too narrow would "trap" vulnerable animals in areas easily searched by predators.
Protection these habitats has two important implications: 1) high value habitat of individuals which have been recruited into the reproductive segment of the population receives special treatment, and 2) the nature and location of secure calving habitat may be passed by association from mother to daughter so habitat of more than one generation is affected.

Travel corridors
Woodland caribou sometimes use traditional routes to move or migrate between summer (calving) and winter range.Distances between seasonal ranges may be large.In one study conducted over a year period, movement from summer calving habitat to winter range averaged 46 km (range 26-80 km) (Cumming and Beange, 1987).Migration distances between summer and winter ranges reflects the juxtaposition of shoreline, summer habitat (anti-predator strategy) and winter lichen supply (Bergerud, 1989a).
Spring movements of females from wintering to calving areas generally occur in April prior to mid-May peak calving.Travelling at this time of year often requires little effort since lakes, streams and bog areas remain frozen with minimal snow cover.Cumming and Beange (1987) described such a movement in the Whitesands River Valley adjacent to Lake Nipigon.Fall shifts to wintering areas occur at any time between late October and early January (Shoesmith and Story, 1977;Cumming and Beange, 1987).
Maintaining travel corridors is important to ensure continuity of caribou range.A 2 km wide corridor, consisting of stands greater than 3.0 m in height, between summer calving and winter range is recommended.This corridor should contain primarily coniferous trees and follow natural features such as streams, valleys, eskers and lichen-rich rock ridges.Its width will assist predator avoidance by increasing predation search time and reducing mortality compared to narrower corridors (Porter, 1983).

Table 1 .
Size of individual wintering areas 3 for radio-collared woodland caribou that occupy boreal forest yearround.
a As determined by minimum convex polygon

Table 2 .
Estimated size of herd wintering areas for herds of woodland caribou that occupy boreal forest yearround, in or adjacent to Ontario.
a Note additional studies are necessary over time to determine factors affecting range size utilization.

Table 3 .
Number of large fires in Red Lake, Sioux