South Purcells Mountain Caribou
A case study of a conservation effort of Mountain Caribou in the South Purcells Mountain Range
Chris Martin
Summary
Mountain Caribou are an endangered species and a top priority of the Species at Risk Act (SARA). Forestry and other industrial activities that clear cut forests have had a significant impact on these animals as they really on food sources that are predominately found in old growth forests. Many agencies and organizations have made significant conservation efforts, however, there are still at great risk. Translocating species has been a popular management strategy for a long time. In 2012 the South Purcells Mountain Caribou herd were facing extirpation, so nineteen Northern Caribou were translocated from Level Kawdy to support this population. In the first sixteen months seventeen of the nineteen donor caribou died, eight to predation events, six of which were by cougars. Northern Caribou are a different ecotype than Mountain Caribou so they did not have the same learned anti-predator behaviour or habitat selection strategies. In the future more research must be done on animal behaviour before translocation events, additionally, other conservation strategies should be considered for particular sub-populations. There are currently paternity pens in the rocky mountains that hope to work on recovering Mountain Caribou populations. Mountain Caribou need continued monitoring, adaptive management, and continued support from dedicated individuals to ensure their populations can recover.
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Ecological Genealogy
The Purcell Range of mountains is located in south-eastern British Columbia and northern Idaho (fig. 1), with peaks typically around 3,000m (Holland, 1976). The South Purcells are home to one of the most threatened mountain caribou populations. It is currently the driest limit of mountain caribous current habitat range. This region is also home to a much larger number of competition and predators than is normal for mountain caribou habitats (Kinley & Apps, 2001).
The South Purcells are a popular destination for forest harvesting (Leech et. al, 2017). This is a detrimental industrial activity to mountain caribou habitat. This species relies on old growth forests as habitat as this is where their primary food source, aboreal lichen, can be found (Leech et. al, 2017). When these forests are cleared the caribous fundamental food source is diminished and the cut-blocks provide habitat for other ungulates (Wittmer et. al, 2010). By promoting other ungulate populations, apparent competition is created. This is when an alternative prey population is doing well, allowing for more predation, which promotes the predator population, increasing the risk of predation on caribou (Leech et. al, 2017). Habitat change and apparent competition are two significant factors that have lead mountain caribou populations in the South Purcells to extirpation (Leech et. al, 2017).
Present Tense
Translocation Conservation Efforts
In the last century translocation and assisted colonization has been a widely-used management strategy in order to restore and/or sustain populations of species (Seddon et. al, 2007). Translocation of caribou have been conducted as early as 1924 (Bergerud & Mercer, 1989). A majority of translocation events are not successful. While it may reduce the risk of extirpation in the short-term, translocation is not a sufficiently effective management strategy to reverse population declines (Decesare et. al, 2010).
In 2012, nineteen caribou were translocated from Level Kawdy, further north, to a group of mountain caribou in the South Purcell Range that were facing the risk of extirpation (Leech et. al, 2017). To study the translocation, each of the nineteen-translocated caribou were radio-collared along with four resident caribou were radio-collared, and seven cougars. In the first sixteen months seventeen of the nineteen translocated caribou had died, eight due to predation (six of which were by cougars) (Leech et. al, 2017). While this translocation met the fate of many before it, the failure could have been avoided. There are two factors discussed as the major cause: 1) increased cougar population size due to abundance of alternative prey; and, 2) a different ecotype was translocated to help preserve the resident ecotype (Leech et. al, 2017). Woodland caribou are split into two different ecotypes in British Columbia, this distinction is largely based on habitat selection (Jones et. al, 2007). Because the northern caribou did not have the same antipredator behavior as mountain caribou they were found to have significant habitat overlap with predators in the South Purcells. The resulting habitat overlap of cougars and northern caribou in union with the lack of anti-predator behavior in northern caribou resulted in the 6 predation events by cougars (Leech et. al, 2017). In the future it will be critical to examine behavioral differences when translocating different ecotypes in attempts to restore another ecotypes population.
With the location data collected from the radio collars, Leech et. al (2017) found there was a significant amount of habitat overlap between translocated caribou and cougars. However, resident caribou had very minimal habitat overlap with cougars, and it was found that for the most part the only overlapping habitat was in regenerating cut-blocks. It is vital that the spatial use of these cut-blocks by at-risk populations and their predators are examined. If use by one of the predator or prey can be deterred conservation efforts would be strengthened. Beese et. al (2003) suggest a forestry approach called “variable retention” in which trees and other structures are retained within a harvested area. This would mean that old-growth trees, which caribou rely on for a food source. Additionally, predators are attracted to cut-blocks as this open habitat provides grazing opportunities for many ungulates. This means if enough trees are retained in the harvested stand there would be less of a draw for these predators to inhabit these areas.
In the last century translocation and assisted colonization has been a widely-used management strategy in order to restore and/or sustain populations of species (Seddon et. al, 2007). Translocation of caribou have been conducted as early as 1924 (Bergerud & Mercer, 1989). A majority of translocation events are not successful. While it may reduce the risk of extirpation in the short-term, translocation is not a sufficiently effective management strategy to reverse population declines (Decesare et. al, 2010).
In 2012, nineteen caribou were translocated from Level Kawdy, further north, to a group of mountain caribou in the South Purcell Range that were facing the risk of extirpation (Leech et. al, 2017). To study the translocation, each of the nineteen-translocated caribou were radio-collared along with four resident caribou were radio-collared, and seven cougars. In the first sixteen months seventeen of the nineteen translocated caribou had died, eight due to predation (six of which were by cougars) (Leech et. al, 2017). While this translocation met the fate of many before it, the failure could have been avoided. There are two factors discussed as the major cause: 1) increased cougar population size due to abundance of alternative prey; and, 2) a different ecotype was translocated to help preserve the resident ecotype (Leech et. al, 2017). Woodland caribou are split into two different ecotypes in British Columbia, this distinction is largely based on habitat selection (Jones et. al, 2007). Because the northern caribou did not have the same antipredator behavior as mountain caribou they were found to have significant habitat overlap with predators in the South Purcells. The resulting habitat overlap of cougars and northern caribou in union with the lack of anti-predator behavior in northern caribou resulted in the 6 predation events by cougars (Leech et. al, 2017). In the future it will be critical to examine behavioral differences when translocating different ecotypes in attempts to restore another ecotypes population.
With the location data collected from the radio collars, Leech et. al (2017) found there was a significant amount of habitat overlap between translocated caribou and cougars. However, resident caribou had very minimal habitat overlap with cougars, and it was found that for the most part the only overlapping habitat was in regenerating cut-blocks. It is vital that the spatial use of these cut-blocks by at-risk populations and their predators are examined. If use by one of the predator or prey can be deterred conservation efforts would be strengthened. Beese et. al (2003) suggest a forestry approach called “variable retention” in which trees and other structures are retained within a harvested area. This would mean that old-growth trees, which caribou rely on for a food source. Additionally, predators are attracted to cut-blocks as this open habitat provides grazing opportunities for many ungulates. This means if enough trees are retained in the harvested stand there would be less of a draw for these predators to inhabit these areas.
The Future
Since 2017 when the Leech et. al paper was published the south Purcell herd of mountain caribou have been deemed functionally extirpated. In a statement made by biologist Leo Degroot, the remaining caribou will be captured and transported to a captive breeding facility north of Revelstoke (CBC, 2018). In their second year of operation, the Revelstoke breeding facility reported fifteen successful calving events and five mortalities (various ages) (Furk & Serrouya, 2016). These numbers are promising but will not be enough to revive a struggling mountain caribou population across North America.
Translocations can still be considered a viable option, despite the failure seen in the South Purcell’s. If proper research is done prior to translocation based on anti-predator behaviour and other behaviours such as foraging patterns and habitat selection then translocation could be successful. In translocation events involving elk it will often take them one to two years to adopt antipredator behaviour (Leech et. al, 2017). With this in mind, it is suggested that in the future calves or juveniles are translocated and placed directly within a resident herd so that they can learn anti-predator behaviour from a young age (Leech et. al, 2017).
In addition to proper considerations prior to translocation, proper land management is also key in conserving and promoting caribou populations. Mountain caribou populations rely on aboreal lichen that only grows in old growth forests, and when these forests are cleared, so is the caribous food source (Leech et. al, 2017). By implementing forestry techniques such as variable retention this critical habitat can remain in place (Beese et. al, 2003) and predators will not be as attracted to caribou habitat.
Serrouya et. al (2019) suggest adaptive management as a conservation strategy. Adaptive management has been traditionally used to encourage sustainable consumption of goods, however, Serrouya et. al (2019) believe it could be very useful in conservation efforts. The authors found that eight of twelve herds that were treated with adaptive management showed population increases and that six of those eight retained stable populations.
Controversial Management Strategies
Perhaps one of the most controversial management strategies for endangered species is a predator cull, in this context it is common for wolves to be culled (Alberts, 2016). However, sometimes apparent competition is culled as well (i.e Elk, Moose, other cervidae) (Wittmer et. al, 2016). While predator control is highly polarizing due to the charisma of many predator species, it has a very high success rate of over 70% with some species conservation efforts (Wittmer et. al, 2016). Regarding caribou, a four-year period of intense wolf management in the Yukon resulted in a population increase of 2.6 individuals/1000km2 (Wittmer et. al, 2016). It has been found that once active culling ceases predator populations will rapidly return to what they were prior to the cull, this means that continuous management of predators is necessary which will require a lot of resources (Wittmer et. al, 2016).
Cull of predators has resulted in concreted data proving it successful, but the proof for reduction in apparent competition has yet to show significance. Sometimes predator population response to reduced prey will be apparent immediately and sometimes there will be a lag in response time, making prey populations more at risk of small population effects (Wittmer et. al, 2016). Because of the uncertainty in this field there has been little research done on the effects of culling apparent competition. Papers do attribute apparent competition to decline in caribou numbers (Leech et. al, 2017) so it may be an effective strategy, despite its controversy.
Translocations can still be considered a viable option, despite the failure seen in the South Purcell’s. If proper research is done prior to translocation based on anti-predator behaviour and other behaviours such as foraging patterns and habitat selection then translocation could be successful. In translocation events involving elk it will often take them one to two years to adopt antipredator behaviour (Leech et. al, 2017). With this in mind, it is suggested that in the future calves or juveniles are translocated and placed directly within a resident herd so that they can learn anti-predator behaviour from a young age (Leech et. al, 2017).
In addition to proper considerations prior to translocation, proper land management is also key in conserving and promoting caribou populations. Mountain caribou populations rely on aboreal lichen that only grows in old growth forests, and when these forests are cleared, so is the caribous food source (Leech et. al, 2017). By implementing forestry techniques such as variable retention this critical habitat can remain in place (Beese et. al, 2003) and predators will not be as attracted to caribou habitat.
Serrouya et. al (2019) suggest adaptive management as a conservation strategy. Adaptive management has been traditionally used to encourage sustainable consumption of goods, however, Serrouya et. al (2019) believe it could be very useful in conservation efforts. The authors found that eight of twelve herds that were treated with adaptive management showed population increases and that six of those eight retained stable populations.
Controversial Management Strategies
Perhaps one of the most controversial management strategies for endangered species is a predator cull, in this context it is common for wolves to be culled (Alberts, 2016). However, sometimes apparent competition is culled as well (i.e Elk, Moose, other cervidae) (Wittmer et. al, 2016). While predator control is highly polarizing due to the charisma of many predator species, it has a very high success rate of over 70% with some species conservation efforts (Wittmer et. al, 2016). Regarding caribou, a four-year period of intense wolf management in the Yukon resulted in a population increase of 2.6 individuals/1000km2 (Wittmer et. al, 2016). It has been found that once active culling ceases predator populations will rapidly return to what they were prior to the cull, this means that continuous management of predators is necessary which will require a lot of resources (Wittmer et. al, 2016).
Cull of predators has resulted in concreted data proving it successful, but the proof for reduction in apparent competition has yet to show significance. Sometimes predator population response to reduced prey will be apparent immediately and sometimes there will be a lag in response time, making prey populations more at risk of small population effects (Wittmer et. al, 2016). Because of the uncertainty in this field there has been little research done on the effects of culling apparent competition. Papers do attribute apparent competition to decline in caribou numbers (Leech et. al, 2017) so it may be an effective strategy, despite its controversy.
References
Alberts, E. C. (2016). Wolves, lies & logging: Racing to save endangered caribou and stop the
wolf cull. Alternatives Journal, 42(2), 66.
Apps, C. D., McLellan, B. N., Kinley, T. A., Serrouya, R., Seip, D. R., & Wittmer, H. U. (2013).
Spatial factors related to mortality and population decline of endangered mountain caribou. The Journal of Wildlife Management, 77(7), 1409-1419. doi:10.1002/jwmg.601
Armstrong, D. P., & Seddon, P. J. (2008). Directions in reintroduction biology. Trends in
Ecology & Evolution, 23(1), 20-25. doi:10.1016/j.tree.2007.10.003
Beese, W. J., Dunsworth, B. G., Zielke, K., & Bancroft, B. (2003). Maintaining attributes of old
growth forests in coastal B.C. through variable retention. The Forestry Chronicle, 79(3), 570-578. doi:10.5558/tfc79570-3
Bergerud, A. T., & Mercer, W. E. (1989). Caribou introductions in eastern north america.Wildlife
Society Bulletin (1973-2006), 17(2), 111-120.
Bottrill, M. C., Joseph, L. N., Carwardine, J., Bode, M., Cook, C., Game, E. T., . . . Possingham,
H. P. (2008). Is conservation triage just smart decision making? Trends in Ecology & Evolution, 23(12), 649-654. doi:10.1016/j.tree.2008.07.007
CBC (2018) In final effort to revive herds, 6 remaining caribou to be relocated to rearing pen.
Retrieved from https://www.cbc.ca/news/canada/british-columbia/in-final-effort-to-revive-herds-6-remaining-caribou-to-be-relocated-to-rearing-pen-1.4888410
Decesare, N. J., Whittngton, J., Hebblewhite, M., Robinson, H., Bradley, M., Neufeld, L., &
Musiani, M. (2010). The role of translocation in recovery of woodland caribou populations. Conservation Biology, 25(2), 365-373. doi:10.1111/j.1523-1739.2010.01609.x
Furk, K., & Serrouya, R. (2016). Revelstoke Caribou Maternity Pen Project Annual Report, Year
2 April 1st 2015 to March 31st, 2016.
Holland, S. (1976), Landforms of British Columbia: A Physiographic Outline. British Columbia
Ministry of Energy, Mines and Petroleum Resources
Jones, E. S., Gillingham, M. P., Seip, D. R., & Heard, D. C. (2007). Comparison of seasonal
habitat selection between threatened woodland caribou ecotypes in central british columbia.Rangifer, 27(4), 111-128. doi:10.7557/2.27.4.325
Kinley, T. A., & Apps, C. D. (2001). Mortality patterns in a subpopulation of endangered
mountain caribou. Wildlife Society Bulletin (1973-2006), 29(1), 158-164.
Leech, H., Jelinski, D.E., DeGroot, L. & Kuzyk, G. (2017) The temporal niche and seasonal
differences in predation risk to translocated and resident caribou (Rangifer tarandus caribou). Canadian Journal Zoology 95, 809–820. DOI: 10.1139/cjz-2016-0076 [This papers shows the effects a predatory landscape on resident and translocated caribou].
Melstrom, R. T., & Horan, R. D. (2014). Interspecies management and land use strategies to
protect endangered species. Environmental and Resource Economics, 58(2), 199-218. doi:10.1007/s10640-013-9699-y
Seddon, P. J., Armstrong, D. P., & Maloney, R. F. (2007). Developing the science of
reintroduction biology. Conservation Biology, 21(2), 303-312. doi:10.1111/j.1523-1739.2006.00627.x
Serrouya, R., Seip, D. R., Hervieux, D., McLellan, B. N., McNay, R. S., Steenweg, R., . . . Boutin, S.
(2019). Saving endangered species using adaptive management. Proceedings of the National Academy of Sciences of the United States of America, , 201816923. doi:10.1073/pnas.1816923116
Wittmer, H. U., Ahrens, R. N. M., & McLellan, B. N. (2010). Viability of mountain caribou in
british columbia, canada: Effects of habitat change and population density. Biological Conservation, 143(1), 86-93. doi:10.1016/j.biocon.2009.09.007
Wittmer, H. U., Serrouya, R. , Elbroch, L. M. and Marshall, A. J. (2013), Conservation Strategies for
Species Affected by Apparent Competition. Conservation Biology, 27: 254-260. doi:10.1111/cobi.12005
World Wildlfie Fund (2016) Caribou. Retrieved from
http://www.wwf.ca/conservation/arctic/wildlife/caribou/
wolf cull. Alternatives Journal, 42(2), 66.
Apps, C. D., McLellan, B. N., Kinley, T. A., Serrouya, R., Seip, D. R., & Wittmer, H. U. (2013).
Spatial factors related to mortality and population decline of endangered mountain caribou. The Journal of Wildlife Management, 77(7), 1409-1419. doi:10.1002/jwmg.601
Armstrong, D. P., & Seddon, P. J. (2008). Directions in reintroduction biology. Trends in
Ecology & Evolution, 23(1), 20-25. doi:10.1016/j.tree.2007.10.003
Beese, W. J., Dunsworth, B. G., Zielke, K., & Bancroft, B. (2003). Maintaining attributes of old
growth forests in coastal B.C. through variable retention. The Forestry Chronicle, 79(3), 570-578. doi:10.5558/tfc79570-3
Bergerud, A. T., & Mercer, W. E. (1989). Caribou introductions in eastern north america.Wildlife
Society Bulletin (1973-2006), 17(2), 111-120.
Bottrill, M. C., Joseph, L. N., Carwardine, J., Bode, M., Cook, C., Game, E. T., . . . Possingham,
H. P. (2008). Is conservation triage just smart decision making? Trends in Ecology & Evolution, 23(12), 649-654. doi:10.1016/j.tree.2008.07.007
CBC (2018) In final effort to revive herds, 6 remaining caribou to be relocated to rearing pen.
Retrieved from https://www.cbc.ca/news/canada/british-columbia/in-final-effort-to-revive-herds-6-remaining-caribou-to-be-relocated-to-rearing-pen-1.4888410
Decesare, N. J., Whittngton, J., Hebblewhite, M., Robinson, H., Bradley, M., Neufeld, L., &
Musiani, M. (2010). The role of translocation in recovery of woodland caribou populations. Conservation Biology, 25(2), 365-373. doi:10.1111/j.1523-1739.2010.01609.x
Furk, K., & Serrouya, R. (2016). Revelstoke Caribou Maternity Pen Project Annual Report, Year
2 April 1st 2015 to March 31st, 2016.
Holland, S. (1976), Landforms of British Columbia: A Physiographic Outline. British Columbia
Ministry of Energy, Mines and Petroleum Resources
Jones, E. S., Gillingham, M. P., Seip, D. R., & Heard, D. C. (2007). Comparison of seasonal
habitat selection between threatened woodland caribou ecotypes in central british columbia.Rangifer, 27(4), 111-128. doi:10.7557/2.27.4.325
Kinley, T. A., & Apps, C. D. (2001). Mortality patterns in a subpopulation of endangered
mountain caribou. Wildlife Society Bulletin (1973-2006), 29(1), 158-164.
Leech, H., Jelinski, D.E., DeGroot, L. & Kuzyk, G. (2017) The temporal niche and seasonal
differences in predation risk to translocated and resident caribou (Rangifer tarandus caribou). Canadian Journal Zoology 95, 809–820. DOI: 10.1139/cjz-2016-0076 [This papers shows the effects a predatory landscape on resident and translocated caribou].
Melstrom, R. T., & Horan, R. D. (2014). Interspecies management and land use strategies to
protect endangered species. Environmental and Resource Economics, 58(2), 199-218. doi:10.1007/s10640-013-9699-y
Seddon, P. J., Armstrong, D. P., & Maloney, R. F. (2007). Developing the science of
reintroduction biology. Conservation Biology, 21(2), 303-312. doi:10.1111/j.1523-1739.2006.00627.x
Serrouya, R., Seip, D. R., Hervieux, D., McLellan, B. N., McNay, R. S., Steenweg, R., . . . Boutin, S.
(2019). Saving endangered species using adaptive management. Proceedings of the National Academy of Sciences of the United States of America, , 201816923. doi:10.1073/pnas.1816923116
Wittmer, H. U., Ahrens, R. N. M., & McLellan, B. N. (2010). Viability of mountain caribou in
british columbia, canada: Effects of habitat change and population density. Biological Conservation, 143(1), 86-93. doi:10.1016/j.biocon.2009.09.007
Wittmer, H. U., Serrouya, R. , Elbroch, L. M. and Marshall, A. J. (2013), Conservation Strategies for
Species Affected by Apparent Competition. Conservation Biology, 27: 254-260. doi:10.1111/cobi.12005
World Wildlfie Fund (2016) Caribou. Retrieved from
http://www.wwf.ca/conservation/arctic/wildlife/caribou/