For good or for ill, humans massively modify the world around them. From the perspective of other species, the majority of our modifications are "for ill." Some individuals realized that humans might irrevocably alter their favourite places, and thus was born the conservation movement out of local concerns. It wasn't until the 20th century that conservation of entire species really took off as a movement, and not until much later that the concept of protecting ecosystems and ecosystem services emerged. Biodiversity has continued to decline, however, leading to a period of mass-extinction that is unseen since the K-Pg extinction event (extinction event formerly known as prince. Er, K-T). Conservation biologists have truly emerged in the last 60 years to attempt to preserve some of this threatened biodiversity, but their over-all impact has been generally unevaluated.
In the latest issue of Science, the International Union for Conservation of Nature has published a systematic review of the current conservation status of vertebrates (verts), and whether conservation has had an impact on the status of those species. Before I get much further, this paper does two things I hate. The first is it has an insanely long list of authors. There's no way that 100+ list of individuals all contributed written material to the paper, and the list of author affiliations literally takes up over a page. That's just ridiculous. Secondly, much of the paper is in the supplementary material - which is seriously abusing the definition of "supplementary."
Now that I've got that off of my chest, the consortium of authors compiled the conservation for 25,780 species of verts - this comprises all described mammals, birds, cartilaginous fish and amphibians, and a sample of reptiles (herps) and bon fish. Why they didn't do a complete enumeration of herps is beyond me. They only used ~ 19% of modern species (by my off-the-cuff estimation), and adding about 6500 more species doesn't seem like it would have been a huge amount of work. Perhaps there's a good reason that I'm missing. Broadly, the IUCN uses three major categories, which are broken down into sub-categories. Threatened species can be either Critically Endangered (CR), Endangered (EN) or Vulnerable (VU). They found that around 1 in 5 vert is classified as threatened, with a gradually increasing trend in risk since the 1980s. Amphibians are far and away the most threatened taxa, with over 600 species of them moving a category closer to extinction (e.g., changing from VU to EN). Generally, this was all known though it's nice to see it reiterated.
Next, the consortium of authors evaluated the impact of conservation efforts on this decline. They argue that of all the 'status' changes, 7% were improvements in status (e.g., CR to EN), and only 4 of these were not due to conservation efforts. Taking a digression here, the consortium do not really define what they mean by conservation. Conservation can be everything from highly intensive captive breeding to mostly laissez-faire restrictions on hunting or killing. It can describe setting aside habitat, or re-introducing a species actively. In short, it covers an awful lot of ground from "doing nothing" to "doing a whole lot." So when they say 64 of 68 improvements is due to conservation, it doesn't say anything about conservation effort. Indeed, some of that improvement could be due to factors not related to the conservation effort at all.
This is not a trivial point. The very title of the paper is "The impact of conservation on the status of the world's vertebrates." This merely confuses correlation of conservation activities with a causal agent in species improvement. When they next compare species status to what they would be, they implicitly bias the equation by assuming that absent conservation, species status would remain unchanged. While it is true that in most instances, threatened species would deteriorate without some degree of conservation, the only way they couldn't find that conservation leads to species improvement is if every species showed a decline. It precludes a species improving due non-conservation related reasons.
There's good reason think that a species wouldn't continuously diminish if left to its own. As species become rare, it becomes difficult for predators to effectively target them. Disease doesn't have as many hosts, so absolute rates can often drop. And species with small home ranges are difficult to stamp out from habitat loss. In rare cases, there have been evidence that some threatened populations have evolved to resist threats posed by invasives. They would be vulnerable to extinction from purely stochastic events (such as the odd harsh winter), but the time frame we're talking about (30 years) is not long enough to really capture that in its entirety.
I would argue that the proof that our current conservation is not as effective as we'd hope it would be is in the universally worsening Red List Index. To the right, there's a map of the net-change, and it's almost universally bad. By congratulating conservation for the cases of conservation, it ignores the cases where conservation has been applied and no improvement has resulted. I wouldn't argue that conservation has
no impact. However, if I stated that my method of healing a bleeding patient caused individuals to improve 7% of the time, no one in their right mind would let me treat so much as a papercut. Conservation effort needs to improve, and seriously, if we're going to stem the global declines in biodiversity. But talk and criticism is cheap; I offer no plausible way through which we can do better. I just hope it isn't status quo.
Hoffmann, M., Hilton-Taylor, C., Angulo, A., Bohm, M., Brooks, T., Butchart, S., Carpenter, K., Chanson, J., Collen, B., Cox, N., Darwall, W., Dulvy, N., Harrison, L., Katariya, V., Pollock, C., Quader, S., Richman, N., Rodrigues, A., Tognelli, M., Vie, J., Aguiar, J., Allen, D., Allen, G., Amori, G., Ananjeva, N., Andreone, F., Andrew, P., Ortiz, A., Baillie, J., Baldi, R., Bell, B., Biju, S., Bird, J., Black-Decima, P., Blanc, J., Bolanos, F., Bolivar-G., W., Burfield, I., Burton, J., Capper, D., Castro, F., Catullo, G., Cavanagh, R., Channing, A., Chao, N., Chenery, A., Chiozza, F., Clausnitzer, V., Collar, N., Collett, L., Collette, B., Fernandez, C., Craig, M., Crosby, M., Cumberlidge, N., Cuttelod, A., Derocher, A., Diesmos, A., Donaldson, J., Duckworth, J., Dutson, G., Dutta, S., Emslie, R., Farjon, A., Fowler, S., Freyhof, J., Garshelis, D., Gerlach, J., Gower, D., Grant, T., Hammerson, G., Harris, R., Heaney, L., Hedges, S., Hero, J., Hughes, B., Hussain, S., Icochea M., J., Inger, R., Ishii, N., Iskandar, D., Jenkins, R., Kaneko, Y., Kottelat, M., Kovacs, K., Kuzmin, S., La Marca, E., Lamoreux, J., Lau, M., Lavilla, E., Leus, K., Lewison, R., Lichtenstein, G., Livingstone, S., Lukoschek, V., Mallon, D., McGowan, P., McIvor, A., Moehlman, P., Molur, S., Alonso, A., Musick, J., Nowell, K., Nussbaum, R., Olech, W., Orlov, N., Papenfuss, T., Parra-Olea, G., Perrin, W., Polidoro, B., Pourkazemi, M., Racey, P., Ragle, J., Ram, M., Rathbun, G., Reynolds, R., Rhodin, A., Richards, S., Rodriguez, L., Ron, S., Rondinini, C., Rylands, A., Sadovy de Mitcheson, Y., Sanciangco, J., Sanders, K., Santos-Barrera, G., Schipper, J., Self-Sullivan, C., Shi, Y., Shoemaker, A., Short, F., Sillero-Zubiri, C., Silvano, D., Smith, K., Smith, A., Snoeks, J., Stattersfield, A., Symes, A., Taber, A., Talukdar, B., Temple, H., Timmins, R., Tobias, J., Tsytsulina, K., Tweddle, D., Ubeda, C., Valenti, S., Paul van Dijk, P., Veiga, L., Veloso, A., Wege, D., Wilkinson, M., Williamson, E., Xie, F., Young, B., Akcakaya, H., Bennun, L., Blackburn, T., Boitani, L., Dublin, H., da Fonseca, G., Gascon, C., Lacher, T., Mace, G., Mainka, S., McNeely, J., Mittermeier, R., Reid, G., Rodriguez, J., Rosenberg, A., Samways, M., Smart, J., Stein, B., & Stuart, S. (2010). The Impact of Conservation on the Status of the World's Vertebrates Science, 330 (6010), 1503-1509 DOI: 10.1126/science.1194442
Figure reproduced from the paper under fair use rationale.
I would argue that the proof that our current conservation is not as effective as we'd hope it would be is in the universally worsening Red List Index. To the right, there's a map of the net-change, and it's almost universally bad. By congratulating conservation for the cases of conservation, it ignores the cases where conservation has been applied and no improvement has resulted. I wouldn't argue that conservation has no impact. However, if I stated that my method of healing a bleeding patient caused individuals to improve 7% of the time, no one in their right mind would let me treat so much as a papercut. Conservation effort needs to improve, and seriously, if we're going to stem the global declines in biodiversity. But talk and criticism is cheap; I offer no plausible way through which we can do better. I just hope it isn't status quo.
They studied snowshoe hares (Lepus americanus) and Dall's sheep (Ovis dalli) in the central portion of the Alaska Range, illustrated by the figure to the right. It's worth noting that though both species are in the Alaska range, they have differing habitat requirements. Whereas hares are happy in the lower foresty areas, the sheep decidedly prefer the rocky hills where they can can try to avoid predators. However, while adult survival among sheep is fairly high, lamb survival is generally lower, as predators (lynx, coyotes, eagles, wolverines) can still prey on them.
When they analysed the adult data, they found that the year really didn't have a major effect on their survival, and that survival was either modeled best as age-specific, or just constant. However, for lambs, the best explanations for the changes in survival were either a three year time lag in hare abundance, positively, or a negative relationship between survival and hare abundance with a one year time lag. The mechanism for changing survival appears to be changes in predation - primarily coyote and golden eagle predation. Accidents and disease seem to remain at a constant low-level throughout all years, whereas predation seems to vary among years. Eagles are best predators early on, whereas coyotes appeared to kill several months after ewes dropped their lambs. As I mentioned before, snowshoe hares and sheep share those predators.
This seems to suggest that although there's a positive relationship between abundance of hares and sheep, it is not, in fact, a mutualistic relationship. If they had just limited their study to abundance, they would have never seen the change in lamb survival. At that point, we would be led to incorrectly believe that snowshoe hares and sheep benefit from each-other's presence. It doesn't appear to be mediated by a functional response in predation - first, a previous study found that coyotes don't switch to sheep when they're low, but secondly, it would mean there would be a positive relationship between hare abundance and sheep survival, not negative.
