Course:CONS200/2023WT1/Population Fragmentation of Lynx Canadensis Across the US-Canadian Border

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(Lynx canadensis) Photo: Keith Williams

Canada Lynx (Lynx canadensis) and Population Fragmentation

The Canadian lynx (Lynx canadensis) is a medium-sized felid found from the northern US to the treeline of Canada’s boreal forests. The range of the Canada lynx in North America has decreased by 40% since pre-settlement times [1]. However, the northern limit of its range has not changed much in the past few decades, but its southern range has been pushed north significantly due to less frequent snowfall and competition with other medium-sized predators [2]. Heightened human activity and increased frequency of wildfires have resulted in the southernmost patches of boreal forest becoming patchy. This has made Lynx populations in those areas scattered and low-density [3]. Much of this range reduction and fragmentation is due to heightened human activity, increasing wildfires, declining mountain snowpack, and timber harvest [3]; [4]. These disturbances all provide key focus areas for conservation efforts.

Population Fragmentation

Effect on Population Dynamics from Habitat Change

The Lynx canadensis is reliant upon the population’s dynamics and how this affects habitat selection and needs. When deciding on a primary habitat, Lynx canadensis are fairly specialized with their hunting and resting habits, however they will transverse great distances through land that does not meet their needs in order to reach a desirable area [3]. This can specifically be seen with lynx crossing the Canadian and US border. Due to this, a decline in lynx population is observed in the United States, however this is not a result of the total species population declining. Rather, this is caused by the lynx moving northward towards preferable habitat. When comparing the current species’ range to a hundred years ago, a reduction in suitable environment is observed, attributed to land modification and climate change[1]. As a result, the lynx habitat has shifted, causing lynx to travel through unfitting and somewhat difficult terrain. Some of these challenges are imposed by human innovation and history, specifically roads and land division. During their movement, lynx will use smaller, concentrated areas as stepping stones that are not big enough to for them to permanently reside [5] but are sparsely distributed throughout the Okanagan Valley[6]. When considering these stepping stones, it becomes evident they exist as a result of habitat fragmentation. This increases the amount of periphery area leading to concerns of population resiliency as those on the edges are often more sensitive to environmental changes [7]. Although there has been an increased amount of habitat fragmentation, especially as a result of the Canadian and US border, a study about Lynx canadensis’ population behaviour when selecting habitats found that due to the lynx’s flexibility and ability to move to find suitable habitat, they are resilient to fragmentation issues when there are lower amounts of suitable habitat [7]. This indicates that although the lynx has specific needs for their habitats, they are willing and ready to move to find what is needed.

Habitat Matrices and Functional Habitat

It has been observed that due to the disconnected nature of their core habitats, Lynx canadensis will pass through lower-quality habitat zones to travel between higher-quality habitats[3]. Such areas are referred to as a habitat matrix, as they are comprised of a series of interlocking areas which are generally not suitable for the lynx's daily activities such as foraging, hunting, mating, and resting, but are instead used as a means of travel during population dispersal[5]. Incorporating habitat matrices into assessments and aggregations of the lynx's habitat provides researchers with a functional habitat measurement. This differs from the traditional measurement of structural habitat, which only accounts for core habitat areas, and as such results in an incomplete view of where the species spends its time[3]. Only using the structural habitat measurement when making conservation decisions can result in decisions which damage the productivity of the habitat matrix, adversely affecting the lynx's capacity to travel between core habitat areas.

Understanding and assessing functional habitat, therefore, is fundamental to the process of making informed conservation decisions regarding Lynx canadensis. Studies around habitat connectivity for the lynx show that, while not ideal core habitat, remnants of forest stands in the resultant char area of a recent wildfire can provide sufficient cover to classify as functional habitat, aiding in the dispersal of lynx populations[8]. Such studies prove that the marginal benefit of preserving less than ideal habitat areas should not be overlooked, as these zones are crucial in facilitating the movement of lynx populations to more suitable habitats. Placing too much emphasis on the conservation of high-quality core habitat zones, which are almost always more expensive and difficult to maintain, can result in an inefficient use of resources and a failure to effectively protect lynx populations from the many pressures that they face[5].

Map of Lynx canadensis current(brown) and probable historical range(beige). From: The Natural History of Canadian Mammals. 2012. Donna Naughton.

Southern Range Contraction

The southern fringe of Lynx canadensis population's distribution range is actively retreating northwards due to a number of factors.

  • The Canada lynx is adapted to cold, boreal forest ecotypes[2]. The combined effects of decreased forest coverage in the northern United States due to continued logging and rising global temperatures leads to the preferred habitat of the lynx contracting into more northern and higher altitude areas[7].
  • The lynx's distribution is found to be highly correlated with the distribution of snowshoe hares (Lepus americanus), which are their primary prey and are also moving north due to the warming winter temperatures[9]. As the snowshoe hares' populations undergo a cyclic variance, with the population densities fluctuating greatly over a period of 9-10 years[10], any disruptions in this cycle will subsequently affect the success of associated lynx populations[9].
  • In the southernmost edge of its range, the Canadian lynx shares the ecological niche of medium-sized felid carnivore with the bobcat (Lynx rufus) and mountain lion (Puma concolor)[2]. Both the bobcat and the mountain lion are similar to the lynx because of their prevalence in lightly forested mountainous regions away from human activity, but differ from the lynx in that they prefer warmer areas with less winter snowpack[11][12]. The lynx has also been observed avoiding areas which have a substantial presence of either of these two competitors, suggesting little to no potential for population overlap and a high degree of pressure exerted by the expansion of these species into the lynx's fundamental niche[9].

The contraction of the lynx's southernmost range due to the aforementioned suitable habitat recession, prey population movement, and competitor species encroachment places it at risk of extirpation in the lower 48 states of the US, which has lead to it being listed as "Threatened" under the United States Endangered species act[2].

Hare Population and Habitat

Habitat and Degradation

Considering the Snowshoe Hare (Lepus americanus) is the main prey for the Lynx canadensis, an understanding of the population dynamics of the Hare is essential in the conservation of its predator. The southern range of the hares habitat has been degraded and fragmented resulting in a reduction of the overall quality of the habitat [13]. The forests which the snowshoe hare resides in have been affected by anthropocentric activities such as clear cutting which creates a habitat that is only capable of supporting a low density hare population [13]. There are also natural causes such as forest fires that play a role in the reduction of snowshoe hare habitat, and recently affected areas cannot support a high density of hares[13]. In order to survive, the hare relies on vegetation to hide from predators as well as occupying a smaller area making minimal movement outside of it to avoid predation[14] . When selecting a habitat the hares must choose between vegetative cover for safety, or food quality, and research has shown that in most cases the safety of vegetation plays a larger role in selection[14]. In moderately dense forests, the population of snowshoe hares is also moderately dense relative to other habitats with more or less vegetation[13].

Concerns For Conservation Of Hare

The ideal habitat for the snowshoe hare is one which consists of dense vegetation capable of providing cover from predation, and one that is also surrounded by habitats of similar quality as these were found to support the highest density populations[13] . Concerning conservation of the hares, maintaining vegetative dense forests that are connected to other habitats is currently the main goal [13]. In the future this goal may prove difficult to achieve given the projected quantity of forest fires that will reduce carrying capacity of the habitats [14]. Through the maintenance of habitats supporting dense hare populations, the conservation of the lynx will be supported as a result.

Current Solutions

Example of a habitat corridor. Photo: Laury Cullen Jr.

Habitat Conservation

Due to lynx populations currently being listed as “threatened” there has been research into current conservation efforts[2]. The lynx habitat is mainly located in areas with large amounts of canopy cover, as this is also where their prey, snowshoe hares, live[3]. Considering the decreasing canopy cover caused by forest fires, and deforestation from industry[3], prioritizing the conservation of critical habitat is also key for the conservation of the lynx. Through the means of habitat conservation, lynx can stay in areas best suited for their survival rather than travel across the border to locate a more comfortable habitat[9]. While there are conservation efforts being made for the lynx habitat, the loss of such habitat areas could be impossible to stop[3].

Habitat Corridors

Through the lens of inevitable habitat loss, other current conservation efforts have focused on making travel to other environments safer. The main method of conservation for lynx populations facing habitat fragmentation is habitat corridors[3], which provide wildlife access to natural areas that are interrupted by human activity. In general, the use of habitat corridors have been found to promote biological diversity and safer travel of animals between habitats[15]. There are some cases however, where the implementation of habitat corridors had no impact on the movement of wildlife[15]. Ultimately the goal of these corridors is to provide connectivity of habitats over roads and other unnatural areas while minimizing human-animal interactions for the safety of both sides[15]. Looking at this method of conservation for the lynx population specifically, it appears the utilization of habitat corridors has had a positive impact on their movement between forest canopies[3]. In the case of lynx, the use of habitat corridors is beneficial as certain populations may not move between canopies if there is insufficient presence of their core habitat[3], so the addition of a corridor will promote this movement.

Map of the Restigouche Watershed. Image: Restigouche River Watershed Management Council Inc.

Restigouche Watershed: Example in Action

The Upper Restigouche provides a strong example of the importance of protected habitat for not only the Canadian lynx, but other species sharing the habitat. The Restigouche River runs for around fifty-five kilometers and its conservation and management has been both a provincial and federal effort[16]. The original intent behind protecting this region of land was freshwater protection, however a myriad of other outcomes occurred as a result of government and community action. The habitat for lynx in New Brunswick, considered endangered in the province, is adjacent to the designated protected area of the river, meaning changes occurring at the designated site affected them as well[16]. These changes were incidental of freshwater conservation, but were greatly positive for the lynx and other endangered animals in the same area. When considering the changes that occurred to the lynx population, the long-term management strategy implemented in this area had perhaps the most noticeable effect, with lynx not only growing their population size but expanding their habitat range [16]. When considering the actions taken and the result, it becomes clear that protecting lynx habitat is a long-term project that requires cooperation from a multitude of political and community bodies. This stresses the importance of stakeholders and organization regarding habitat conservation. However, despite these positives results, it must also be considered that the expansion of lynx habitat is only possible due to the continual and long-term management of this designated area – if the management system was dissolved the progress made would fade and the previous problems would return. Ultimately, there are many ways to support Canadian lynx and their habitats, but what remains common is the need for consistent, continual, and planned action.

Possible Future Solutions

Functional Habitat Identification and Policy Recommendations

In the face of a changing climate, worsening forest fires, habitat degradation and anthropogenic disturbances, the ability for lynx to shift their ranges and adapt to such changes is highly dependent on habitat connectivity [5]. Studies have shown that lynx tolerate less-appealing landscapes that facilitate their travel and allow them to find new home ranges, mates, escape degraded habitats, and exchange genes[5]. Low lynx connectivity as a result of fragmented habitat results in few choices for escape from poor conditions. Thus, future conservation efforts must focus on protecting functional habitat that is broadly favourable for lynx. Vanbianchi et al. (2018), state that "maintaining such poor-but-useful habitats may become especially critical as severe wildfires become increasingly common and forest wildlife need to move between remnant patches of core habitat as recently burned areas regrow into more suitable conditions" (p. 11305)[5]. Identifying and conserving lynx habitat (including such habitat that may have been previously overlooked because of its 'poorer' suitability for the Canada lynx) is an important path forward in addressing lynx population fragmentation.

Protected Areas

A study in Glacier National Park, at the border between Canada and the United States, revealed that protected areas could be refugia for Lynx canadensis. Protected areas like Glacier National Park are generally safe from habitat degradation and anthropogenic disturbances that could otherwise worsen lynx population fragmentation. Additionally, they cover diverse landscapes with high connectivity suitable for lynx range shifts. Considering the current migration of many species upslope in response to changing climate zones and increased wildfires, the study suggests that more research into how protected areas can serve as refugia could be the path to understanding future lynx population dynamics[17].

The International Union for Conservation of Nature (IUCN) defines a protected area as "a clearly defined geographical space, recognized, dedicated and managed, through legal or other effective means, to achieve the long-term conservation of nature with associated ecosystem services and cultural values" [13]. There are six management types of protected areas.

  • The most restrictive type is Ia: Strict Nature Reserve which excludes any human activity in the area. In terms of protecting Lynx canadensis from further anthropogenic disturbance, a strict Nature Reserve could be a solution[13].
  • Management type IV: Habitat/species management area, demonstrates further future protective measures which makes them even more desirable. Type IV focuses much more on the conservation of a particular species, and implements management strategies uniquely focused on this species[13].

The conservation and restoration of currently fragmented Lynx canadensis habitat could benefit greatly from such management strategies.

Satellite image of wildfires burning near Hanceville, British Columbia. Photo: Pierre Markuse

Wildfire Management

Wildfires pose a significant risk for population and habitat degradation for the Canada lynx. The lynx's desired habitat of dense forest canopy cover is more vulnerable to fires. A significant strategy to combat this can be through the evaluation and understanding of the intersection of forest management, lynx habitat conservation, and reducing wildfire risk, and how this can be translated into policy[18]. Furthermore, increasing wildfire risk demands lynx habitat conditions that are able to inhibit stand-replacing fires and therefore maintain more canopy cover. Conservation and restoration efforts should focus on silviculture, fire, and forest management systems that benefit lynx in these ways.[4]

Prescribed Burning

An often overlooked aspect of the increasingly severe issue of wildfire damage to forest habitats is that of improper management. While climate change is certainly exacerbating the issue, a fundamental cause of the increasing frequency, severity, and size of wildfires in forested areas in North American boreal forests is the history of colonial fire suppression[19]. In a misguided attempt to protect the land they had colonized and oppress the cultural practices of the Native peoples, European settlers made active and targeted efforts to suppress all forms of fire in forest ecosystems, including the prescribed cultural burns practiced by many first nations[19]. This had and continues to have an adverse effect on forest ecosystems, as the buildup of coarse woody debris leads to excess fuel loads in forests. This mismanagement of fuel resources has led to a nation-wide increase in vulnerability to severe and uncontrolled wildfires, the worst of which could be avoided with the implementation of prescribed burning[20]. Prescribed burning, especially when done using Indigenous Ecological Knowledge, is effective at reducing the severity and wide-scale damage of wildfires by reducing the fuel load incrementally[21]. By incorporating matrix habitats into wildfire risk modelling, conservation decision-makers can maximize the effectiveness of prescribed burning by developing priority threat management plans based on area risk analyses, and created forest ecosystems that are less prone to massive burning and therefore more suitable for Lynx canadensis to use as both core and matrix habitat[20].

Conclusion

The conservation of the Canadian lynx in its receding habitat range is crucial to the persistence of smaller, fragmented populations. The Canada lynx is a somewhat resilient animal that researchers have said may be able to lessen its sensitivity to habitat alteration caused by humans by altering habitat selection patterns[7]. Despite this potential ability, habitat fragmentation and change remains a major issue as lynx on the edges of their habitat, even one they have altered habitat selection to, have lower survival and are more sensitive to environmental variability[7]. The range of the Canada lynx is notably wide and as this is a highly mobile species, current solutions for the conservation of the Canada lynx include the construction of habitat corridors. Habitat corridors provide safe travel for animals over roads and other unnatural areas[15]. Additionally, extensive research is being completed to outline the best ways to identify and conserve lynx habitat and restore fragmented regions. Future solutions to the fragmentation of Canada lynx habitat consider the use of protected areas as a conservation mechanism as well as prescribed burning to protect lynx habitat from more destructive wildfire. Research of such solutions and case studies like Glacier National Park provide critical information and evidence for policymakers to implement effective conservation of the Canada lynx. Canada lynx (Lynx canadensis) needs efficient and effective policy if we hope to protect it from future population and habitat fragmentation.


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References

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  1. ↑ 1.0 1.1 Marrotte, Robby; Bowman, Jeff (March 9, 2021). "Seven decades of southern range dynamics of Canada lynx". Ecology and Evolution. 11 – via Wiley.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Lavoie, M; Renard, A; Larivière, S (2019). "Lynx canadensis (Carnivora: Felidae)". Mammalian Species. 51(985): 136–154.
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 Vanbianchi, Carmen; Gaines, William L; Murphy, Melanie A; Pither, Jason; Hodges, Karen E (August 2017). "Habitat selection by Canada lynx: making do in heavily fragmented landscapes". Biodiversity and Conservation. 26: 3343–3361 – via Springer Link.
  4. ↑ 4.0 4.1 Lyons, A.L; [...] Fitkin (April 11, 2023). "Climate change, wildfire, and past forest management challenge conservation of Canada Lynx in Washington". The Journal of Wildlife Management. 87 – via Wiley.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Vanbianchi, Carmen; Gaines, William L; Murphy, Melanie A; Hodges, Karen E (November 2018). "Navigating fragmented landscapes: Canada lynx brave poor quality habitats while traveling". Ecology and Evolution. 8: 11293–11308 – via ProQuest.
  6. ↑ Koehler, G.; Maletzke, B.; von Kienast, J.; Aubry, K.; Wielgus, R.; Naney, R. "Habitat fragmentation and the persistence of lynx populations in washington state". The Journal of Wildlife Management. 72 – via Wiley. line feed character in |title= at position 77 (help)
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Hornseth, M.L.; Walpole, A.A.; Walton, L.R.; Bowman, J; Ray, J.C.; Fortin, M.J.; Murray, D.L. (2014). [doi: 10.1371/journal.pone.0113511. "Habitat loss, not fragmentation, drives occurrence patterns of Canada lynx at the southern range of periphery"] Check |url= value (help). PLoS One. 9.
  8. ↑ Vancianchi, Carmen M; Murphy, Melanie A; Hodges, Karen E (April 2017). "Canada lynx use of burned areas: Conservation implications of changing fire regimes". Ecology and Evolution. 7: 2382–2394 – via ProQuest.
  9. ↑ 9.0 9.1 9.2 9.3 Scully, Arthur E; Fisher, Scott; Miller, David A. W.; Thornton, Daniel H (2018). "Influence of biotic interactions on the distribution of Canada lynx (Lynx canadensis) at the southern edge of their range". Journal of Mammalogy: 760–769.
  10. ↑ Krebs, Charles J.; Bryant, John; Kielland, Knut; O'Donoghue, Mark; Doyle, Frank; Carriere, Suzanne; DiFolco, Donna; Berg, Nathan; Boonstra, Rudy (2014). "What factors determine cyclic amplitude in the snowshoe hare (Lepus americanus) cycle". Canadian Journal of Zoology: 1039–1047.CS1 maint: display-authors (link)
  11. ↑ Popescu, Viorel D; Kenyon, Madeline; Brown, Ryan K; Dyck, Marissa A; Prange, Suzanne; Peterman, William E; Dennison, Catherine (2021). "Habitat connectivity and resource selection in an expanding bobcat (Lynx rufus) population". PeerJ. 9: 2–10.
  12. ↑ Laurie, Michelle A; Nielsen, Clayton K; Dowling, Mark; Miller, Ken; Wilson, Bob; Shaw, Harley; Anderson Jr., Charles R (2012). "Cougars are Recolonizing the Midwest: Analysis of Cougar Confirmations During 1990-2008". The Journal of Wildlife Management. 7: 1365–1368.
  13. ↑ 13.0 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 Lewis, C.W; Hodges, K.E; Koehler, G.M; Mills, L.S (2011). "Influence of stand and landscape features on snowshoe hare abundance in fragmented forests" (PDF). Journal of Mammalogy. 92: 561–567. Cite error: Invalid <ref> tag; name ":8" defined multiple times with different content
  14. ↑ 14.0 14.1 14.2 Feierabend, D; Kielland, K (2015). "Seasonal effects of habitat on sources and rates of snowshoe hare predation in Alaskan boreal forests". PLOS ONE. 10.
  15. ↑ 15.0 15.1 15.2 15.3 Beier, P; Noss, R.F (1998). "Do habitat corridors provide connectivity?". Conservation Biology. 12: 1523–1739.
  16. ↑ 16.0 16.1 16.2 Restigouche River Watershed Management Council Inc. (2021). (rep.). Upper Restigouche – Canadian Heritage Monitoring Report 2010-2020. Canadian Heritage Rivers Board. Retrieved from https://chrs.ca/sites/default/files/2022-02/10%20Year%20Monitoring%20Report_Upper_Restigouche_2010-2020.pdf.
  17. ↑ Anderson, A. K; Waller, J. S; Thornton, D. H (2023). "Canada lynx occupancy and density in glacier national park". The Journal of Wildlife Management. 87.
  18. ↑ Holbrook, J. D; Squires, J. R; Bollenbacher, B; Graham, R; Olson, L. E; Hanvey, G; Jackson, S; Lawrence, R. L; Savage, S. L (2019). "Management of forests and forest carnivores: Relating landscape mosaics to habitat quality of Canada lynx at their range periphery". Forest Ecology and Management. 437: 411–425.
  19. ↑ 19.0 19.1 Vinyeta, Kirsten (April 2021). "Under the guise of science: how the US Forest Service deployed settler colonial and racist logics to advance an unsubstantiated fire suppression agenda". Environmental Sociology. 8: 134–148 – via Taylor & Francis Online.
  20. ↑ 20.0 20.1 Matsypura, Dmytro; Prokopyev, Oleg A; Zahar, Aizat (January 2018). "Wildfire fuel management: Network-based models and optimization of prescribed burning". European Journal of Operational Research. 264: 774–796 – via ScienceDirect.
  21. ↑ Findlay, Alyssa (May 2021). "Climate mitigation through Indigenous forest management". Nature Climate Change. 11: 371–373 – via ProQuest.
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