Forest Investment Account (FIA) - Forest Science Program
FIA Project M075047

    Tweedsmuir-Entiako caribou project: effects of a mountain pine betle epidemic on Northern caribou habitat use 2006/07
Project lead: Cichowski, Deborah
Author: Cichowski, Deborah B.
Imprint: Smithers, B.C. : Caribou Ecological Consulting, 2007
Subject: Forest Investment Account (FIA), Dendroctonus Ponderosae, Caribou, British Columbia, Ecology
Series: Forest Investment Account (FIA) - Forest Science Program
The Tweedsmuir-Entiako caribou population summers in the North Tweedsmuir Park area, moves through the East Ootsa area during spring and fall migration, and winters in the Entiako and East Ootsa areas. During winter, caribou select mature lodgepole pine forests on low productivity sites where terrestrial lichens are abundant, and forage primarily by cratering through the snow to obtain terrestrial lichens (Cichowski 1993). The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has recently listed all caribou in the Southern Mountains National Ecological Area (SMNEA), which includes the Tweedsmuir-Entiako population, as Threatened. As a signatory to the National Accord for the Protection of Species at Risk, B.C. is obligated to develop a recovery strategy that addresses the threats to the species and its habitat. One of the greatest threats currently facing the Tweedsmuir-Entiako caribou population is the impact of the extensive mountain pine beetle outbreak on winter forage (terrestrial lichens), on caribou habitat and winter range use, and on population dynamics. Since this scale of mountain pine beetle attack has been unprecedented on caribou ranges in recent history, there is no information available on the effects of mountain pine beetles on caribou habitat use and population dynamics, and little information on caribou winter habitat (terrestrial lichens), making it difficult to develop management prescriptions that minimize impacts to caribou. The Tweedsmuir-Entiako caribou population is the first population to experience the current mountain pine beetle epidemic; information collected on the Tweedsmuir-Entiako population will also benefit other caribou populations where mountain pine beetle will occur. The Recovery Strategy for Northern Caribou in the SMNEA in BC identifies research on the effects of mountain pine beetles on Northern Caribou as a priority (Northern Caribou Technical Advisory Committee 2004). The current mountain pine beetle epidemic was detected in the East Ootsa and North Tweedsmuir Park areas in the early 1990s. By the late 1990s, mountain pine beetle numbers reached epidemic levels along Eutsuk and Tetachuck lakes. The area on the south and north side of Tetachuck Lake is an important spring migration staging area and winter range for the Tweedsmuir-Entiako caribou, and the area south of Tetachuck Lake in Entiako Park and Protected Area is the main part of the caribou winter range. By 2005, most mature lodgepole pine stands in the Tweedsmuir-Entiako caribou winter range are under heavy or moderate attack by mountain pine beetles and are in the 'grey attack' phase of the mountain pine beetle epidemic. Three of the most critical questions that need to be answered regarding the impacts of the mountain pine beetle epidemic on caribou are: How will caribou winter habitat be affected by mountain pine beetle attack? (i.e. how will terrestrial lichens respond? will snow accumulation increase due to a loss of canopy and/or will eventual blowdown lead to impeded movements?); How will caribou winter range and habitat use be affected by extensive mountain pine beetle attack? (i.e. will caribou avoid using mountain pine beetle-attacked habitats for traveling or foraging during winter and migration and/or will they alter foraging strategies in beetle killed areas?); and, How will caribou population dynamics be affected by extensive mountain pine beetle attack? (i.e. will mortality rates and causes and/or population growth change following the mountain pine beetle epidemic). In 2001, a project was initiated in both the East Ootsa and Entiako areas to monitor the response of terrestrial lichens to mountain pine beetle attack (East Ootsa and Entiako areas) and forest harvesting (East Ootsa area only), and to monitor changes in coarse woody debris as an indicator of movement barriers. Preliminary data from 2003 suggest that kinnikinnick (Arctostaphylos uva-ursi) is proliferating on some sites and affecting terrestrial lichen abundance (Williston and Cichowski 2004). However, no information has yet been collected on how caribou habitat use is changing in response to mountain pine beetle disturbance or whether population dynamics have been affected. Mountain pine beetle disturbance will likely start affecting caribou habitat use now that areas are advancing from red attack to grey attack (i.e. trees that have lost their dead needles) with a corresponding change in snow interception. It is important to examine both changes in caribou habitat (lichen study Williston and Cichowski 2004) and changes in caribou habitat use and population dynamics to determine the overall impacts of mountain pine beetles on caribou. This project focuses on how caribou winter range and habitat use will be affected by extensive mountain pine beetle attack. Caribou select habitat at different spatial scales (Cichowski 1993) and therefore will likely respond to disturbances on different spatial scales. At the landscape scale, caribou may avoid large areas within their ranges if large-scale disturbances or increased human activity occurs. Also at the landscape level, caribou occasionally shift their range use patterns, presumably to avoid overgrazing of lichens. Therefore, large-scale disturbances such as this mountain pine beetle epidemic could affect their ability to shift ranges. At the stand level, caribou may continue using individual stands affected by disturbance if they are interspersed within undisturbed areas. For example, caribou may continue to use mountain pine beetle killed stands if they are able to travel to them in unaffected stands. That is, they may tolerate barriers to movement within the stands that they forage in if sufficient movement is possible in adjacent stands. In addition, the population currently appears to be declining and therefore winter range use patterns need to be addressed in the context of a declining population. Since recovery planning needs to address both critical (current) and recovery habitat, the ability of caribou to use beetle-attacked winter range will be an important consideration for the recovery group when determining the amount and configuration of recovery habitat required compared to what is currently available. Because the Tweedsmuir-Entiako caribou population is the first Northern Caribou population to experience the current mountain pine beetle epidemic, it provides the first opportunity to collect information on the response of caribou to a mountain pine beetle epidemic and therefore to develop management strategies to deal with this issue. As time passes without conducting this project, the state of the mountain pine beetle epidemic will continue to progress and valuable information on the response of caribou to the early stages of the mountain pine beetle epidemic in the 'grey attack' phase may be lost. Information collected in this study will aid in identifying forest stands on other caribou winter ranges that will be important caribou winter range following epidemic mountain pine beetle levels and therefore will aid in directing mountain pine beetle management and salvage efforts to minimize impacts on this species at risk.


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Updated August 16, 2010 

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