When I started looking into spider conservation, I wasn’t sure how much information I would find, but I assumed that there was a growing body of literature. And that is accurate, although I was surprised to see how much of it was about the impact of land management practices on spider communities in general. There are definitely endangered spiders and also some very specific studies on spider ecology, but many of the papers I found looked at agricultural practices or fragmentation and how specific spider populations responded (often wolf spiders- it would appear that wolf spiders are very popular).
I’ll get to some of that research in a moment, but I want to start with a quick glance at the general health of spider species: a look through the CITES appendices shows that 22 species, all of them tarantulas, are listed in Appendix II (for a refresher on CITES, check out my post from April 2013)- this seems to be connected to their popularity in the exotic pet trade; when I visited the IUCN Red List site, I counted 13 Vulnerable, 1 Near Threatened, 5 Endangered, and 7 Critically Endangered spider species– several genera [including Paraheliophanus (jumping spiders) and Poecilotheria (Indian and Sri Lankan tarantulas)] had multiple species listed, so it seems like certain groups are particularly at risk. Included among the vulnerable species is the Lake Placid funnel wolf spider- since many of the species I’ve mentioned already are tropical species, it’s important to note that temperate species possibly found in our backyards are at risk, too.
A Kauai cave wolf spider transporting young- these cave dwellers have lost their eyes. Photo by Wendy Kashida/USFWS
What factors make certain species or groups of species vulnerable? As has been mentioned so many times before in this blog, habitat loss and fragmentation are big issues– a 1995 review of spider conservation in Australia found that land management practices and habitat loss were the main concerns (Yen 1995). The same is true in locations around the world. A study in Arizona found that, while spider abundance increased in agricultural areas and yards (think of all that extra water…), spider diversity was greatest in the original desert areas (Shocat et al. 2004). Regular plowing of agricultural fields lowers spider diversity, too (Haskins and Shaddy 1986). Uetz (1991) suggested that spiders are particularly sensitive to changes in soil and vegetative structure because they use vibrations to locate prey and often need specific conditions for web construction. Certain species are also vulnerable to habitat fragmentation because they move within very small areas- for example, Eresus spiders tend to create burrows close to their mother’s web (Krause et al. 2011).
Some spider species are also in precarious positions because they are found across a very small range. Ysnel et al. (2008) found that in Europe endemic species were concentrated along the Mediterranean and in caves- indeed, the smallest spider in Europe is endemic to a cave in the Iberian Peninsula (Cardoso 2008). Caves in general are important locations for spiders with small ranges- there’s the Kuaui cave wolf spider in Hawaii (also known as the no-eyed big-eyed wolf spider…), the Kanthan cave trapdoor spider in Malaysia, and the Dolloff cave spider in California and Texas, just to name a few.
And I think it’s important to include generally negative public attitudes which don’t place a lot of importance on monitoring and protecting spider populations. Kellert’s (1993) research on perceptions of invertebrates found that spiders in particular generated a lot of fear and dislike from the public. As a result, most respondents said they would not support major efforts to protect endangered spiders (they also said the same for molluscs…).
So, if there are a variety of black marks against spider conservation, do we at least have some ways to move forward, too? In my next post, I’ll look at what we’re learning about the best ways to protect spider species in danger.
Works cited:
Cardoso P. 2008. Biodiversity and conservation of Iberian spiders: past, present and future. Boletin Soc. Entomol. Aragon. 42:487–492.
Haskins MF, Shaddy JH. 1986. The ecological effects of burning, mowing and plowing on ground-inhabiting spiders (Araneae) in an old-field system. J. Arachnol. 14:1–13.
Kellert SR. 1993. Values and perceptions of invertebrates. Conserv. Biol. 7:845–855.
Krause RH, Buse J, Matern A, Schroder B, Hardtle W, Assmann T. 2011. Eresus kollari (Araneae: Eresidae) calls for heathland management. J. Arachnol. 39:384–392.
Shocat E, Stefanov WL, Whitehouse MEA, Faeth SH. 2004. Urbanization and spider diversity: influences of human modification of habitat structure and productivity. Ecol. Appl. 14:268–280.
Uetz GW. 1991. Habitat structure and spider foraging. In: Bell SS, McCoy ED, Mushinsky HR, editors. Habitat Structure: The Physical Arrangement of Objects in Space. London, UK: Chapman & Hall. pp. 325–348.
Yen AL. 1995. Australian spiders: an opportunity for conservation. Rec. West. Aust. Mus. 52:39–47.
Ysnel F, Petillon J, Gerard E, Canard A. 2008. Assessing the conservation value of the spider fauna across the west palearctic area. J. Arachnol. 36:457–463.
I imagine many people have seen garden spiders like this one- photo courtesy of USFWS
For people who know me, this month’s topic may come as something of a surprise- I am not good with spiders, I do not like them close to me, I get creeped out watching them move. But I’m also trying to be open-minded when it comes to conservation concerns- just because I don’t personally like an animal, or plant for that matter (not a fan of black locust trees, either- mowing the lawn around them can get painful at times…), is no reason to turn a blind eye to their decline. It’s true that people are often motivated to contribute to conservation efforts when the species is charismatic- for example, with pandas or elephants or bald eagles- but that doesn’t negate the importance of preserving entire ecosystems, including the less-appealing parts.
So, when I saw a news story about scientists researching the color patterns of tarantulas and determining that the different species had developed blue coloring at least 8 times, that got me thinking about these creatures that I generally would prefer to avoid. I know very, very little about spiders in general- they aren’t bugs, their webs can be very sticky, they eat other things I don’t appreciate like biting insects. I have no idea if they, like other invertebrate species, are facing survival challenges from an increasingly human-altered and -dominated world. If they are, I don’t know if there are already groups working for spider conservation.
This month I’ll be walking on the web side, trying to learn as much as I can about spider conservation issues and whether there is some role that I can play as well. Time to look these animals more fully in the face.
When I started looking into opportunities to get involved with squirrel conservation, I expected to see many efforts that focus on the European Red Squirrel in the UK and Ireland- and my expectations were more than met. In fact, I had to do a little digging to find groups that even mentioned other squirrel species, but they are out there, and there are many, many ways to participate in squirrel conservation.
Starting with the most popular kid at squirrel school, you’ve got a number of options for helping European red squirrels (and this is only a tiny sample of the groups out there- I didn’t want to run out of space before I got to any other species…)- from the UK Forestry Commission’s Red Squirrel Conservation work to the Red Squirrel United Project, or the Red Squirrel Survival Trust, or Scottish Wildlife Trust’s Saving Scotland’s Red Squirrel program, or any of the other regional groups, you can donate time and/or money, you can report sightings, you can take part in monitoring surveys, and, for those of us on the far side of the pond who have suddenly realized how close the end of the year is, you can buy Allerdale Red Squirrel Group’s 2016 calendar.
The Delmarva fox squirrel population is growing thanks to conservation efforts. Photo courtesy of USFWS
I did manage to find a research project involving red squirrels in North America that was looking for public help, but the VT Center for Ecosystem Studies wants volunteers to help document bird nest and squirrel distribution to better understand the impact of red squirrels on nestling survival- it’s not about protecting red squirrels, but it is research about squirrels, and they do want help from everyone.
Looking at other squirrel species in North America, several programs have specifically targeted species living in forests across the continent- Oregon Fish & Wildlife has a “Living with Wildlife: Tree Squirrels” factsheet; Conservation Northwest is looking for donations and volunteers to help them monitor the western gray squirrel and the Pacific Biodiversity Institute needs volunteers to help deploy hair tubes as part of a population study for the same subspecies; Washington Fish & Wildlife provides plans for nest boxes that work for both Douglas and flying squirrels; the Humane Society Wildlife Land Trust has a sanctuary creation and monitoring program for wildlife including the southern flying squirrel; and, if you just want to ensure tree squirrels are regular visitors to your yard, there are squirrel feeder designs.
There are also a number of conservation efforts that focus on ground squirrels- Defenders of Wildlife has been working to protect the Mohave ground squirrel and the Ojai Valley Land Conservancy has been working to protect the California ground squirrel; Wild Earth Guardians has a prairie dog protection program, and they are looking for volunteers to help with office work and photography; both the Great Plains Restoration Council and Northern Rockies Conservation Cooperative include prairie dogs in their conservation work and you can make donations to their organizations; and the Utah Prairie Dog Habitat Credits Exchange and Safe Harbor Program encourages ranchers to maintain habitat for prairie dogs in return for financial benefits.
So there are lots of ways we can get involved with squirrel conservation, whether we want to directly participate in squirrel protection or contribute from a distance, whether we want to focus on squirrels leaping from tree to tree or on squirrels in underground burrows, and whether we want to work just with squirrel species or broaden our efforts to the entire ecosystem. And, if you think that perhaps efforts to support squirrel populations don’t really make a difference, check out the latest announcement about the Delmarva fox squirrel for some good news on the squirrel front.
In my last post, I provided a long (and depressing) list of squirrel species and subspecies facing challenging situations. The very good news is that there are quite a few people conducting research to better understand exactly why certain populations are in decline and how to most effectively reverse those trends. Not all of their results provide solutions, but each piece of information gives us better insight into what is happening and suggests ways to approach each problem.
To start with the European red squirrel, we know a bit more about its population dynamics and the challenges it faces- the virus, for example, is actually a chordopox rather than a parapox (Rushton et al. 2006). While we’re still figuring out how to fight the virus itself, Rushton et al.’s (2006) research indicated that red squirrel populations decline 17-25 times faster when the disease is present than when uninfected gray squirrels are in the area, so keeping the infection from spreading in the gray squirrel population could really make a big difference to red squirrels. In terms of dealing with the gray squirrels themselves, when researchers compared trapping the animals for removal with using an immunocontraceptive to keep local populations from reproducing, they found that the method of control wasn’t as important as how wide an area was being targeted (Rushton et al. 2002). Control methods had the biggest impact on red squirrel persistence in areas that were at the edge of gray squirrel expansion- in other words, don’t wait until red squirrel populations are surrounded to take action.
Another way to support red squirrels may be moving squirrels between isolated populations to ensure that rates of inbreeding are limited (Barratt et al. 1999). Translocation of animals can be a risky venture- the local population may have developed adaptations to their specific ecosystem that the newcomers won’t have, translocated animals may range outside of the intended area and be exposed to a variety of risks during their movements, and social animals may face challenges integrating into the local population. But it can also help maintain genetic diversity, re-establish extirpated populations, and restore species’ ecosystem roles. Translocation of southern fox squirrels onto islands in South Carolina was successful in establishing new populations (Dawson et al. 2009), but the researchers cautioned that the number of animals released should make allowances for losses to predators and take into account that some squirrels may have lower reproductive rates than other squirrel species.
Tassle-eared (or Aberti’s) squirrels require ponderosa pine habitat (Photo courtesy NPS)
We’ve also learned more about other squirrel species that are the focus of conservation efforts. Northern flying squirrels seem particularly affected by the age structure of forests (Holloway and Smith 2011), so land management practices that leave older trees in place could be helpful, and the density of snags may be especially important. Mahan et al. (2010) also suggested that white-tailed deer, which feed on conifers during winter periods and can kill trees if they graze too intensively, should be managed to prevent local populations from limiting conifer tree recruitment. Since sometimes there are conflicting conservation priorities, for example northern flying squirrels and red-cockaded woodpeckers which both nest in cavities, Borgo et al. (2010) investigated whether trapping squirrels for removal made any appreciable difference in nest success for woodpeckers- their results suggest that adding nest boxes for squirrels to use may be a better strategy since squirrel trapping would need to cover a large area in order to be really effective.
The issue of connectivity remains central to squirrel conservation in a variety of habitats. When researchers tracked a number of dispersing juvenile Franklin’s ground squirrels, they found that, while one male successfully crossed at least 4 roads to get to a new colony, at least two other animals were turned back by the barrier of a road (Martin and Heske 2005). Maintaining safe corridors for movement between colonies could be very important in connecting populations, whether on the ground or at an arboreal level. The tassle-eared squirrel is dependent on ponderosa pine habitat with good canopy for moving between locations- management decisions to suppress fires and allow logging changed forest age structures and fragmented larger systems, making it more difficult for squirrel populations to find the habitat they need and maintain contact with other areas (Prather et al. 2006).
So we have a better sense of what makes systems work for squirrels: connectivity; forests with older, larger trees or snags; protection from disease. But we also know that some squirrels are facing some pretty tough odds- is there a way for us to help them out? In my final post of the month, I’ll investigate the options we have for supporting, directly and indirectly, squirrel conservation.
Works cited:
Barratt EM, Gurnell J, Malarky G, Deaville R, Bruford MW. 1999. Genetic structure of fragmented populations of red squirrel (Sciurus vulgaris) in the UK. Mol. Ecol. 8:S55–S63.
Borgo JS, Conover MR, Conner LM. 2010. Flying squirrel removal does not reduce their use of simulated red-cockaded woodpecker nest clusters. Southeast. Nat. 9:813–820.
Dawson JR, Lee JC, Osborn DA, Miller KV. 2009. Survival, movements and habitat use of translocated southern fox squirrels. Am. Midl. Nat. 162:335–345.
Holloway GL, Smith WP. 2011. A meta-analysis of forest age and structure effects on northern flying squirrel densities. J. Wildl. Manag. 75:668–674.
Mahan CG, Bishop JA, Steele MA, Turner G, Myers WL. 2010. Habitat characteristics and revised gap landscape analysis for the northern flying squirrel (Glaucomys sabrinus), a state endangered species in Pennsylvania. Am. Midl. Nat. 164:283–295.
Martin JM, Heske EJ. 2005. Juvenile dispersal of Franklin’s ground squirrel (Spermophilus franklinii) from a prairie “island.” Am. Midl. Nat. 153:444–449.
Prather JW, Dodd NL, Dickson BG, Hampton HM, Xu Y, Aumack EN, Sisk TD. 2006. Landscape models to predict the influence of forest structure on tassel-eared squirrel populations. J. Wildl. Manag. 70:723–731.
Rushton SP, Gurnell J, Lurz PWW, Fuller RM. 2002. Modeling impacts and costs of gray squirrel control regimes on the viability of red squirrel populations. J. Wildl. Manag. 66:683–697.
Rushton SP, Lurz PWW, Gurnell J, Nettleton P, Bruemmer C, Shirley MDF, Sainsbury AW. 2006. Disease threats posed by alien species: the role of a poxvirus in the decline of the native red squirrel in Britain. Epidemiol. Infect. 134:521–533.
When I said last week that I was interested in squirrel conservation, I had imagined that I would find a lot of papers talking about the decline of European red squirrels (Sciurus vulgaris) in response to the presence of gray squirrels in the UK- and, I did. But I also found so much more: more species of squirrel than I knew existed, more conservation issues facing squirrels, more moments when I thought “What were they thinking?” So this week I’ll start with an overview of the red squirrel-gray (or grey) squirrel issue and then look at some of the other species around the world.
European red squirrels in the UK (a different species from the red squirrels in North America which are Tamiasciurus hudsonicus) are incredibly cute and also inhabit a range that is severely reduced– North American gray squirrels were introduced in 1876 in Cheshire and then in several other locations (why?) in the UK until 1937 when it became illegal to introduce or move around gray squirrel populations (Shuttleworth 2003). Research into interactions between red and gray squirrels indicates that red squirrels avoid areas with high gray squirrel densities and, while female red squirrels seem to be able to raise the same number of young whether or not gray squirrels are in the area, once those young red squirrels are on their own they seem to have reduced survival (Wauters et al. 2000). Disease is also a concern since gray squirrels can be asymptomatic carriers of parapox virus, a virus that causes lesions and death in the red squirrels (Rushton et al. 2000). And lest you think there is something about red squirrels in the UK that makes them uniquely vulnerable to competition and disease-transmission by gray squirrels, similar patterns of population decline after introduction of grays have been seen in Ireland and northern Italy (Teangana et al. 2000; Wauters and Gurnell 1999).
The threatened Northern Idaho ground squirrel has a USFWS recovery plan- photo by Diane Evans-Mack, Idaho DFG
Okay, European red squirrel populations are having trouble where they share space with introduced gray squirrels, but surely other squirrel species are doing fine, right? As it turns out, while squirrel species in Louisiana are doing well enough to have a hunting season, other species are facing considerably bigger challenges. Northern flying squirrels in North America, for example, are generally doing well across the northern part of their range (and a good thing, too, since they are an important food resource for predators like spotted owls), but two subspecies in the Appalachians were listed as endangered in 1985 (Loeb et al. 2000) and there are concerns about subspecies in the Rockies and Sierra Nevadas (Weigl 2007). The flying squirrel of Europe (once again, a different species from the one in North America- maybe we need to get a bit more creative with names?) is also declining in parts of its range- the culprits in general seem to be habitat loss and fragmentation (Reunanen et al. 2000). A subspecies of the fox squirrel, the big cypress fox squirrel is found only in Florida and is now considered a threatened subspecies due to loss of mature pine and cypress forests (Eisenberg et al. 2011).
Turning to species with more restricted distributions, the Franklin’s ground squirrel has been in decline in the eastern part of its range, for example in Indiana (Johnson and Choromanski-Norris 1992) and Illinois (Martin et al. 2003)- loss of habitat to agricultural land and the use of herbicides along railway tracks are believed to contribute to the population loss. Habitat loss and fragmentation seem to be the big issues overall, whether it’s loss of open prairie to agriculture as with the Perote ground squirrel in Mexico (Valdez and Ceballos 1997), loss of contiguous forest to roadways so that flying squirrels cannot reach new areas (Weigl 2007), or the introduction of alien plants to meadows for the Northern Idaho ground squirrel (which may not seem like a big deal for animals that eat plants, but, in this case, the new plants were considerably lower in polyunsaturated fatty acids and the squirrels could not get enough energy to last through hibernation- Sherman and Runge 2002). If you want to get a sense of how quickly these smaller populations can blink out, the third case is a pretty grim illustration- within 12 years the studied population had declined by more than 95%. And just to throw in the political side as well, the Mt. Graham red squirrel was listed as an endangered subspecies in Arizona in 1987 while living in a place that could also be used for large telescopes since the atmosphere is so clear- check out Warshall (1994) for the story of how the environmental impact review process doesn’t always follow proper procedure…
The list I just gave of species and subspecies in trouble is rather depressing- and I didn’t mention (until now) the prairie dogs I helped study in northern Mexico where colony sizes declined considerably over a ten-year period. So I want to close with a little look at the bright side– in 1994 in a remote location in northern Pakistan, a species not seen since 1924 was rediscovered (Zahler 1996). The woolly flying squirrel was known from specimens largely collected in the 19th century, but a female was caught and the remains of a second animal were found in the nest of an eagle owl in 1994, showing that this largely unknown species was still present in the mountains of central Asia. Squirrels can be resilient.
Now that you have a sense of the scale and general trends of squirrel conservation issues, for my next post I’m going to try to get more detail on recent developments and possible strategies for supporting those populations in need of help.
Works Cited:
Eisenberg DA, Noss RF, Waterman JM, Main MB. 2011. Distribution and habitat use of the big cypress fox squirrel (Sciurus niger avicennia). Southeast. Nat. 10:75–84.
Johnson SA, Choromanski-Norris J. 1992. Reduction in the eastern limit of the range of the Franklin’s ground squirrel (Spermophilus franklinii). Am. Midl. Nat. 128:325–331.
Loeb SC, Tainter FH, Cazares E. 2000. Habitat associations of hypogeous fungi in the Southern Appalachians: implications for the endangered northern flying squirrel (Glaucomys sabrinus coloratus). Am. Midl. Nat. 144:286–296.
Martin JM, Heske EJ, Hofmann JE. 2003. Franklin’s ground squirrel (Spermophilus franklinii) in Illinois: a declining prairie mammal? Am. Midl. Nat. 150:130–138.
Reunanen P, Monkkonen M, Nikula A. 2000. Managing boreal forest landscapes for flying squirrels. Conserv. Biol. 14:218–226.
Rushton SP, Lurz PWW, Gurnell J, Fuller R. 2000. Modelling the spatial dynamics of parapox disease in red and grey squirrels: a possible cause of the decline in the red squirrel in the UK? J. Appl. Ecol. 37:997–1012.
Sherman PW, Runge MC. 2002. Demography of a population collapse: the Northern Idaho ground squirrel (Spermophilus brunneus brunneus). Ecology 83:2816–2831.
Shuttleworth C. 2003. A tough nut to crack: red squirrel conservation in Wales. Biologist 50:231–235.
Teangana DO, Reilly S, Montgomery WI, Rochford J. 2000. Distribution and status of the red squirrel (Sciurus vulgaris) and grey squirrel (Sciurus carolinensis) in Ireland. Mammal Rev. 30:45–56.
Valdez M, Ceballos G. 1997. Conservation of endemic mammals of Mexico: the Perote ground squirrel (Spermophilus perotensis). J. Mammal. 78:74–82.
Warshall P. 1994. The biopolitics of the Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis). Conserv. Biol. 8:977–988.
Wauters LA, Gurnell J. 1999. The mechanism of replacement of red squirrels by grey squirrels: a test of the interference competition hypothesis. Ethology 105:1053–1071.
Wauters LA, Lurz PWW, Gurnell J. 2000. Interspecific effects of grey squirrels (Sciurus carolinensis) on the space use and population demography of red squirrels (Sciurus vulgaris) in conifer plantations. Ecol. Res. 15:271–284.
Weigl PD. 2007. The northern flying squirrel (Glaucomys sabrinus): a conservation challenge. J. Mammal. 88:897–907.
Zahler P. 1996. Rediscovery of the woolly flying squirrel (Eupetaurus cinereus). J. Mammal. 77:54–57.
Pretty charismatic for a rodent, right? Photo by Simon J. Tonge
Last week I read a news story about an investigation launched by police after a squirrel was shot in Scotland- the issue here is not just that a squirrel was shot, but that a red squirrel was shot. In the UK, red squirrels are a protected species and various organizations are engaged in trying to keep the species, familiar to many of us from Beatrix Potter stories, from disappearing from the British Isles. In contrast, the fox and gray squirrels where I live are not only fair game, but served up for dinner- last week I also met some very friendly squirrel dogs who looked like they have the kind of stamina needed to pursue their quarry.
Quite a different state of affairs for the three species: the first is subject to conservation efforts in one place, and the other two are subject to bag limits in another. The disparity between these situations made me think about other squirrel species and wonder how other populations are faring. Most of my personal experience with squirrels comes from seeing them in the trees as I walk around outside and caring for orphaned and injured animals in Texas- in either case, squirrels seemed to have a lot of energy and even rage at times (it takes a lot of energy to yell so much at people as they walk by- not sure that I want to imagine the level of angst needed to sustain that behavior…). I also have a basic sense of squirrel ecology (eating nuts, sleeping in trees, piling up with other squirrels to keep warm in cold weather), but I don’t know much about squirrel conservation or even if such efforts are needed; red squirrels in the UK are protected, but red squirrels in the US, a completely different species, are not.
So this month I’m going to see what I can dig about squirrel populations around the world- my guess is that some species are doing just fine, but there are probably some populations that are faced with a changing world and limited options for addressing those changes.
Photo courtesy of USFWS
Over the last few posts, I’ve mentioned that a number of groups around the world are working to reduce human-carnivore conflict- some of those strategies have been more successful than others, but we do have a better sense of what helps limit conflict, both from the human and the wildlife perspective.
To get insight into some of the challenges faced by people trying to accommodate wildlife, check out the Waterton Biosphere Reserve Association– their short film “Sharing the Range” is informative and inspiring (and the footage of grizzly cubs running around is awesome!).
If you share your location with large carnivores, there are a number of sources that offer ideas for coexisting with them:
• For black bears, check out the Missouri Dept. of Conservation’s page on how to ID and prevent damage from bears
• Project CAT provides information on living with cougars
• Defenders of Wildlife have a guide on non-lethal tools and methods to reduce conflict with wolves
• USDA Forest Service participates in a program to limit human-carnivore conflict
• Further afield, the EU provides information for living with large carnivores in Europe
You can also help out large carnivore survival by aiding researchers who are working to better understand the needs of carnivores, the points of conflict, and the options for reducing that conflict:
Some options for donations include
o Endangered Wolf Center
o Niassa Carnivore Project
o Mountain Lion Foundation
o Wildlands Project
There are also ways to directly contribute to research, for example by tracking large carnivores in the Carpathian Mountains or monitoring carnivores in Finland– I know those locations may seem very far away, but the reading I’ve done over the past few weeks suggests that scientists all over are happy to benefit from public help with carnivore research, so contact your local fish and wildlife agency or a nearby university- your eyes, ears, legs, etc. could be in great demand!
And probably the most important thing is to remember that keeping large carnivores in their ecosystems is a task for everyone- for people who interact with them on a daily basis, it takes tolerance and efforts to minimize contact; for people living in areas that have lost large carnivores, it means helping the first group bear the costs of sharing their space.
In the past few years there has been an emphasis on assessing what makes a carnivore conservation effort successful (or not) and what the long-term prospects are for the variety of strategies in use. The reality is that there is no magic bullet or guarantee of success, but we certainly have a better sense of what will increase the odds that large carnivores are present in the future.
In my previous post I mentioned that large carnivores tend to need lots of space, which can be in short supply in human-dominated landscapes. This becomes easier to provide when we think of protected areas as part of a network linked by corridors- if animals can disperse between populations through the corridors of good habitat, then we no longer have isolated groups of animals. An analysis of reserve planning scenarios in South Africa found that the size of a reserve was most important in reducing the probability of extinction for African wild dog, cheetah, and lion populations (because bigger reserves can support larger carnivore populations), but connection between those patches was what would keep the species present across the landscape over the long-term because, if one population went extinct, animals from another could recolonize the area (Di Minin et al. 2013). What do we mean by corridors? Typically we are talking about stretches of undeveloped or less-developed land that provide animals with cover and a food source while they are in transit between locations- this can occur at many different scales: strips of forest between fields, smaller preserves spaced out between larger ones, specially-designed overpasses for wildlife to cross major roads, even hedgerows along mown lawns. Not only can corridors help large carnivores move between protected areas, but they can also help them find the resources they need in the patchwork of habitats in developed areas. When I drive to the coast for field work, for example, I pass a section of major road with forest on both sides and “bear crossing” signs. The area is largely covered with agricultural fields, but the small patches of forest and undeveloped areas connected by corridors, such as the one I drive through, allow black bears to survive amid the human presence. And I have seen bears there and just to the west who looked pretty healthy.
Protected areas did not keep leopards in the Phinda-Mkhuze complex in South Africa safe from human-caused mortality because the cats ranged outside of reserves. Photo from USFWS
Often, however the survival of large carnivore populations is about more than just having space. Carnivores, as their name indicates, eat other animals and that includes animals that we also eat, so there is often conflict between humans and large carnivores over issues of prey and general safety. Groups around the world have been exploring strategies for minimizing this conflict. Conflicts over livestock are particularly important (Winterbach et al. 2013), and one option is to pay farmers for loss of livestock- ‘payments to encourage coexistence’ (Dickman et al. 2011). One challenge here is that payment needs to include not only the current value of the animal lost but also future value, for example the lost potential for lambs when a ewe is killed. Another issue is that the farmers may be nomadic or tenant-farmers and therefore have difficulty getting access to compensation for lost animals. Another option for promoting human-carnivore coexistence is to make payments that encourage certain behaviors that either limit conflict or provide resources carnivores need (‘payments for ecosystem services’). An example of the first is creating carnivore-proof corrals for livestock, while the second could mean letting certain areas go untilled. Namibia even has a ‘predator-friendly beef’ program so that consumers can support farms that use practices limiting conflict with carnivores (Winterbach et al. 2013). Oftentimes these programs are created and imposed from outside of the community, which can limit their effectiveness if local people don’t really feel like they have ownership or control. In response to this, some groups have organized locally-financed insurance programs where local farmers pay into a fund that will compensate them in the event of livestock loss to carnivores. An example of this is Project Snow Leopard in Pakistan which combines local contribution to and oversight of an insurance scheme with citizen science and educational opportunities for community members (Rosen et al. 2012).
To a large extent, carnivore conservation efforts succeed or fail based on the attitudes of governments and the local people (Winterbach et al. 2013). Poaching of wolves in Scandinavia had a significant impact on the population’s recovery (Liberg et al. 2012), while communities in some parts of Pakistan have shown growing acceptance of snow leopard presence as they felt more included in conservation efforts (Rosen et al. 2012). In Germany, Luchtrath & Schraml (2015) found that hunters in areas without lynx were far more concerned with who was pushing efforts to initiate lynx reintroduction than what impact the reintroduced animals might have, which suggests that relationships between groups involved in and affected by carnivore conservation are as important as the relationships between people and the carnivores.
So what about our relationships with large carnivores– how can we participate in sustaining large carnivore populations? In my final post of the month, I will look at things we can do to keep large carnivores alive and functioning in their ecosystems.
Works cited:
Di Minin, E, Hunter, LTB, Balme, GA, Smith RJ, Goodman, PS and R Slotow. 2013. Creating larger and better connected protected areas enhances the persistence of big game species in the Maputaland-Pondoland-Albany biodiversity hotspot. PLoS ONE 8: e71788.
Dickman, AJ, Macdonald, EA and DW Macdonald. 2011. A review of financial instruments to pay for predator conservation and encourage human-carnivore coexistence. Proceedings of the National Academy of Sciences of the United States of America 108: 13937-19344.
Liberg, O, Chapron, G, Wabakken, P, Pedersen, HC, Hobbs, NT and H Sand. 2012. Shoot, shovel and shut up: cryptic poaching slows restoration of a large carnivore in Europe. Proceedings of the Royal Society B 279: 910-915.
Luchtrath, A and U Schraml. 2015. The missing lynx- understanding hunters’ opposition to large carnivores. Wildlife Biology 21: 110-119.
Rosen, T, Hussain, S, Mohammad, G, Jackson, R, Jenecka, JE and S Michel. 2012. Reconciling sustainable development of mountain communities with large carnivore conservation: lessons from Pakistan. Mountain Research and Development 32: 286-293.
Winterbach, HEK, Winterbach, CW, Somers, MJ and MW Hayward. 2013. Key factors and related principles in the conservation of large African carnivores. Mammal Review 43: 89-110.
When looking at large carnivore conservation this past week, it became evident that there are lots of layers to this topic. It’s about more than habitat availability or prey populations- it also includes the individuality of species and human attitudes.
Our attitudes toward brown bears tend to depend on our age, sex, and location. Photo by Terry Tollefsbol
To begin with, there is the nature of carnivore ecology– these animals have large home ranges, low population densities, and slow population growth. As a result, they tend to be sensitive to habitat loss and are slow to recover from population declines. [There are exceptions to this last bit- coyotes, for example, increase litter size and decrease age of sexual maturity in response to increased population mortality (Knowlton et al. 1999.)- but coyotes are also an interesting case of being the top predator in some systems and a middle-tier predator in others…] So, an initial question is whether a particular location has enough usable habitat to support large carnivores. The question of food availability is also important- are there enough prey individuals for the large carnivores to eat? When we take these questions and apply them to a long-term outlook (let’s say 100-200 years), we may find that the amount of space required to answer ‘yes’ to both questions becomes very, very big because we need to sustain a large enough population to avoid inbreeding, survive unexpected disasters, etc. Planning on this scale can feel overwhelming, and Noss et al. (1996) suggested looking at the issue as comprised of metapopulations, meaning that there are multiple populations in smaller areas connected by immigration. This can reduce the scale of planning, but means that you have to protect access corridors between populations so that animals can successfully reach new areas. One interesting aspect of human perspectives in areas with large carnivores is the extent to which we (don’t) recognize disturbance. Among people who leave more urban environments for rural settings because they want to be in an ecosystem that still supports large carnivores, many don’t realize how much of the area has been developed because it’s less than in their previous location (Jobes 1991).
Different species will respond to habitat development and human presence in different ways, which means that you can’t simply say ‘carnivore conservation works by x, y, and z…’ Bears have shown themselves adaptable to human presence [for example, raiding trash dumpsters for food (Herrero 1985)], but this means that there is an increased chance for conflict with humans. In contrast, wolverines in Norway were particularly sensitive to habitat fragmentation when compared with wolves, bears, and lynx (May et al. 2008).
And we appear to have different attitudes and responses to various carnivore species. Despite the fact that mountain lions cause more injuries to people in North America than wolves, we see wolves as the big threat, often without having any previous (negative or otherwise) experience with the animals (Kellert et al. 1996). A survey in Latvia found that people supported protection for rare brown bears and population control for more common wolves and lynx (Andersone & Ozolins 2004), so some of our opinions are tied to perceived abundance of species. Older age groups tend to have more negative views of large carnivores (Kellert et al. 1996, Andersone & Ozolins 2004), and attitudes toward large carnivores in Austria were more positive in areas from which they had only recently disappeared (Zeiler et al. 1999). In short there are a lot of factors that influence how we respond to the presence of large carnivores.
So what does this all mean? Apart from the message that each species and location seems to be a special case, what does this say about large carnivore conservation? Well, first of all it suggests that we need to think about more than just protected spaces- we have to think about local communities, the possibilities for human-carnivore conflict, and a variety of other issues. It also means that, the better we understand a carnivore’s ecology, the better we can figure out what it will take to sustain it in specific situations and, indeed, if that goal is realistic.
The research outlined above is constantly being added to and there are bound to be new insights into large carnivore conservation from the past few years. In my next post, I’ll look into more recent studies and see what they suggest for a world big enough to include us and large predators.
Works cited:
Andersone, Z and J Ozolins. 2004. Public perception of large carnivores in Latvia. Ursus 15: 181-187.
Herrero, S. 1985. Bear Attacks: Their Causes and Avoidance. New York: Nick Lyons Books.
Jobes, PC. 1991. The greater Yellowstone social system. Conservation Biology 5: 387-394.
Kellert, SR, Black, M, Rush, CR and AJ Bath. 1996. Human culture and large carnivore conservation in North America. Conservation Biology 10: 977-990.
May, R, van Dijk, J, Wabakken, P, Swenson, JE, Linnell, JDC, Zimmermann, B, Odden, J, Pedersen, HC, Andersen, R and A Landa. 2008. Habitat differentiation within the large-carnivore community of Norway’s multiple-use landscapes. Journal of Applied Ecology 45: 1382-1391.
Noss, RF, Quigley, HB, Hornocker, MG, Merrill, T and PC Paquet. 1996. Conservation biology and carnivore conservation in the Rocky Mountains. Conservation Biology 10: 949-963.
Knowlton, FF, Gese, EM and MM Jaeger. 1999. Coyote depredation control: and interface between biology and management. Journal of Range Management 52: 398-412.
Zeiler, H, Zedrosser, A and A Bath. 1999. Attitudes of Austrian hunters and Vienna residents toward bear and lynx in Austria. Ursus 11: 193-200.
These are the carnivores I normally find in my study sites
A friend of mine 
recently returned from a year of field work in the Southwest- she’s investigating how carnivore species respond to each other and different levels of human activity in an arid environment. Some of the pictures from her camera traps make me completely jealous- she’s dealing with mountain lions and badgers and ringtails, a whole slew of species in a wide range of sizes; in comparison, the carnivores at my field sites are generally coyotes and raccoons, raccoons and coyotes, with the occasional mink or otter thrown in, and my largest carnivore is smaller than the dog waiting to welcome me home each evening.
I was thinking about the differences between our study areas- one very dry and the other pretty wet most of the time, one with large areas of undeveloped land and the other ringed by agriculture and the petroleum industry- and I started wondering whether southern Louisiana could support the larger carnivores she had wandering around her sites. Do we have the space and food resources? And what kind of accommodations would human society have to make to these larger predators?
Predator control and reintroduction are important, and controversial, topics in ecology, whether we are talking about wolves in Yellowstone, leopards killing cattle in Africa, or whether or not mountain lions are present in New England. I don’t know how well either of those strategies works, nor do I have a good sense of what it means to be a large carnivore living in a human world, aside from the impression that it’s pretty tough going at times.
So this month I’m going to focus on large carnivore research, specifically the aspects of their ecology that at most at odds with the modern, developed human landscape I see around me, and whether coexistence is a feasible option. I expect there will be some strong and different opinions on these topics, and I imagine that some situations can’t be win-win, but there are probably more possibilities than we think for supporting those species at the top of the food chain.
