Tuesday, April 21, 2015

To fence or not to fence, that is the question*


The stereotypical view of African drylands is often of a parade of elephants marching steadily across endless expanse of savannah grassland –free to roam. Another staple image, especially of African savannah documentaries, is the massive wildebeest migration where thousands of individual animals moving as an aggregation navigating the hazards of the landscape.

Majestic African animal migrations. Main image: "Wildebeest-during-Great-Migration" by Bjørn Christian Tørrissen - Own work by uploader, http://bjornfree.com/galleries.html. Licensed under CC BY-SA 3.0 via Wikimedia Commons. Inset: By Amoghavarsha amoghavarsha.com (Own work) CC BY-SA 3.0 via Wikimedia Commons

In both of these examples, animals are moving with purpose for food and water, because this is how an animal survives in a place where rainfall and vegetation are seasonably variable. These migrations are vital to the survival of many dryland species. But even at smaller scales, and much less dramatically than a massive migration, animals need to move through a landscape to access food, water and mates.

Yet, as human populations spread their influence by altering ecosystems, they increasingly come in contact with wildlife, and often compete with them for space, water and agricultural crops. To reduce these human-wildlife conflicts, people often erect fences to exclude species and steer them elsewhere. Farmers and ranchers, concerned with their livelihood, need to exclude grazers from crops and predators from domesticated animal herds.

Example of a dryland fence barrier. From: Photo by William I. Boarman, USGS, From press release: USGS Report Finds Too Few Studies Assess the Success of Desert Tortoise Recovery Actions, Aug. 10, 2006. http://online.wr.usgs.gov/ocw/g_agassizii/barrier_fence.jpg

While fencing might offer some protection to human interests, fences can also have broad long-term consequences for animal populations. However, it is also increasingly appreciated that fencing can be used as a conservation measure to protect animals from these conflicts and from illegal hunting. In a thoughtful paper on dryland fencing policy, Durant and colleagues argue that current fencing policies are often based on limited information, with an under appreciation of the large-scale, long-term consequences of fencing nature.

Durant and colleagues argue that fencing can result in multiple costs and benefits. They cite an important example –fencing to protect lions. Fences constructed as a lion conservation tool may result in higher lion population sizes –which seems to valid fencing as a conservation tool; but yet analyses showed that when carrying capacities are accounted for, fences may not provide better protection, and further may not be worth the economic and ecological costs.

Lions of the Masai Mara –do they benefit from fences? Photo by Benh LIEU SONG (Own work) CC BY-SA 3.0 via Wikimedia Commons    
 The authors recommend that fencing policy needs to driven by evidence, and not a reaction to human-wildlife conflict alone. The critical factors that they suggest are: 1) Economic sustainability of erecting and maintaining fences, and that the benefits justify the costs; 2) The permeability of the barrier, because not all species will equally perceive the fence as a hard edge, and so a fence may not be a well justified as a universal management tool; 3) Using fencing within a landscape context –fences may complicate how animals deal with natural features, such as cutting off a natural river crossing; 4) Connectivity is critical for both the maintenance of genetic variability within populations and allowing animals to access variable and ephemeral resources; 5) Ensuring that fences do not interfere with or reduce the delivery of ecosystem services; and finally 6) Safeguarding the wellbeing of human communities, especially marginalized and vulnerable groups that might depend on resources from natural areas.

By creating international policy and regulations based on these six criteria, Durant and colleagues argue that sensible fencing policy can be developed, which ensures that fences are used to maximally benefit humans, animals and natural processes.

 *Note -this post was originally written for the Applied Ecologist's Blog.

Monday, April 20, 2015

The wonder(ful) years? Being a postdoc.

A surprising number of academics talk about their postdocs the same way some people talk about high school – as the best time of their life. It’s enough to make you feel like you’re doing something wrong if you don’t feel the same way :). In fact, postdoc jobs vary greatly and are usually a bit more complex than the “wonderful time to do the research you love and have few responsibilities” memories.

The truth is, every postdoc position and postdoctoral fellow is different, and each has its own strengths and weaknesses. Not every postdoc will be a glorious NCEAS position--self-directed, collaborative, community-oriented (and in Santa Barbara). And not every postdoc will be part of a funded, predetermined research project where you are just a cog in the lab-machine. (Though some people would legitimately prefer the latter to the former).

There are many great aspects to being a postdoc. After a PhD, you no longer need to take classes, you may not need to teach, and research is finally your primary focus. Even better, ‘the thesis’ isn’t looming over your head. And usually you make actual money, rather than poverty-level grad student wages, even if the actual amount is modest. Finally, you probably don’t have nearly as many responsibilities as the average tenured or tenure-track academic (and so, the assumption is, your stress levels are better). (And for those who need a little ego boost, you occupy a slightly better position in the lab hierarchy, maybe you get a better office and get a little more respect.) Best of all, you can finally stop saying you’re a student.

These are all wonderful in theory, but sometimes the reality is more complex. Because academic positions, including postdocs, are hard to find, not everyone will be able to land a position that is well-matched to their skills and research interests. This can feel frustrating, since academics in general want intellectual stimulation and skill development. Finding the perfect lab is difficult, and finding the perfect lab with money to pay you is even harder. As a result, that perfect path on the CV from PhD to postdoc lab where you expand your skills or fine-tune your interests is exceptional.

For many people, the postdoc is a time with a large set of associated stresses; first and foremost, “what’s next?” (for you, your family, your career, your geographic position on the earth...). This is the period when the next position and, more generally, your career, is at the forefront. And the timeframe in which you must sort everything out is short, since most postdoc positions last only 1-3 years. It is not uncommon to run out of funding before the next position has been acquired. Get a group of postdocs together in a room, and the undercurrent of worry will be palpable.

And of course, the short length of most postdoc jobs means that you will probably have to move more frequently than ever. Combined with the unorganized nature of postdoc labour, this can make for a lonely time. In smaller departments, postdocs are few and transient, making it difficult to feel part of a community. No longer a student, not quite a faculty, only temporarily in a place, it can be hard to find a sense of belonging.

None of this is to bemoan the postdoc life, just to note that as with all things, it has pros and cons. I like being a postdoc. I’ve also been lucky to have independent funding though, which no doubt has made things easier. Still, the upsides have included the ability to developing a research plan for the long term (and to make mistakes and fail while the stakes are still low), to supervise undergraduates, to develop a new skills or viewpoints, and definitely to have time for manuscript writing. But I do hope that these aren’t the *best* research years of my life, because—like high school—things can always improve. 

(or any job, really)

Friday, April 3, 2015

Invasion of the Beavers

Guest post by John Cherkas


Fifty years ago, Dr. Walter Howard presented his thoughts on invasive mammals at a symposium on colonizing (invasive) species, which was later turned into the volume "The Genetics of Colonizing Species." He speculated on the nature of predator-prey interactions, population growth limits and habitat disruptions. His ideas still resonate, but how well do they match up with a certain invasive mammal today.

May I bring your attention to some invasive beavers? Our national creature has been making quite a mess is the Southern most reaches of the Western Hemisphere. In the 1940s, Argentina was seeking economic improvements and imported beavers, mink and muskrat to Tierra del Fuego in an attempt to establish a fur trade. That fur trade didn't turn out as expected. Within a few years, beavers had colonized the entire island and were soon crossing channels to reach other Chilean islands, including Cape Horn, a UNESCO Biosphere Reserve.

Angry beaver -roar!

The ecological effects have been pretty well researched recently by Dr. Christopher B. Anderson. In seeing if beavers behave differently in their new habitat than back home, he’s been finding a few differences in the environment and beavers here. One of the most obvious changes is that the beaver colonies are at least twice as dense in Cape Horn. Is this for lack of predators or an abundance of food? So far, I couldn’t say, but I’d lean toward the latter. The Cape Horn forests are entirely southern beeches, which provide ample resources for the beavers’ engineering projects.

But how disruptive have beavers been to the environment: and environment that has no animal that makes such a massive environmental impact as the beaver. Howard suggested that an animal moving into a habitat where its niche doesn’t exist would have wider impacts than one who’s niche does exist. It’s fairly clear that the beaver’s landscaping projects is not something that other animals (except humans) partake in.

In the beaver situation this ecological disruption holds true. The floral assemblage in Cape Horn has never had to deal with beaver-like behaviour. The beavers foraging and building habits prevent forest regrowth, and provide a pathway for other plants to invade. It seems this beaver introduction might be a good example of invasional meltdown. The Chilean archipelago is home to quite a few invasive species already, and this synergistic effect is definitely concerning.

All the beaver-induced worries come with a grave concern for the natural environment. Cape Horn is referred to as pristine quite a bit by Anderson. Is this the place to have a deep political, socio-economic discussion about “pristine” environments? No, not today; you’ll have to read elsewhere for that. Cape Horn is certainly already at risk from invasive species. Beavers have a tremendous impact on the ecological structure of streams and forests. I am certainly one to wonder whether the eradication effort can be truly successful and both removing the beavers and reversing the environmental changes.

I surely hope that the environmental disruption can be reversed. Unfortunately we cannot look back to Howard to speculate on what happens when we remove an alien species. Just fifty years ago, species invasions were seen as a great research opportunity, not something to be extensively managed or eradicated.

Further Reading:

C.B. Anderson et al. (2006), The effects of invasive North American beavers on riparian plant communities in Cape Horn, Chile. Do exotic beavers engineer differently in sub-Antarctic ecosystems? Biological Conservation, 128: 467-474.
doi:10.1016/j.biocon.2005.10.011


C. Choi, (2008) Tierra del Fuego: the beavers must die. Nature 453: 968. doi:10.1038/453968a