Blog Action Day: The Climate Challenge for Birds

This year's Blog Action Day is devoted to meeting the challenge of a changing climate. In honor of the occasion, I am reposting a post from 2007 on the changes in land use and biodiversity that we can expect over the next half-century. I liked this study when it was first published because it looks specifically at birds and because it deals with the interrelated problem of habitat degradation. Both climate change and habitat degradation are serious problems in their own right; habitat degradation is not only harmful to biodiversity but also amplifies greenhouse gas emissions since natural ecosystems store carbon better than artificial ones. Proposed solutions to climate change that harm natural habitats are unlikely to be helpful in the long run.

Climate Change, Land Use, and Biodiversity

A study published this week in the open-access journal, PLoS Biology, argues that many species of birds face range reduction due to climate change and landscape alteration. Approximately 400 of the 8750 species studied will lose more than half of their range by 2050. That number could rise to 900-1,800 species by 2100. The largest effects on bird diversity are expected to occur in the tropics because many ranges there are already small.

The study used four scenarios for climate change and land alteration derived from Millennium Ecosystem Assessment models. The scenarios present the likely future distribution of 18 types of land cover under different models of economic development (globalization vs. regionalization) and conservation actions (proactive vs. reactive). Maps created from those scenarios were compared against the current distribution of 8,750 birds (pdf) to identify species that are likely to suffer range loss. (1,125 species (pdf) were not included; most of these appear to be waterfowl, seabirds, gulls, and waders, which are somewhat less dependent on land cover.)

Changes in land cover are likely to be concentrated in high latitudes and in the developing world. At high altitude the changes are predominantly due to climate change. In Central and South America, central Africa, and southern Asia, development and deforestation play a more critical role than climate change. Changes due to economic development rather than climate change would be a greater factor when ecosystems are managed reactively (addressing problems only after they occur) rather than proactively. Consequently, range reductions are likely to be greatest without active environmental protection.

The authors identify several factors that could alter their results. One factor that could worsen range loss for some species is habitat specialization. The effects of disease and invasive species will have their own impact, as well. Range shifts and adaptation to new habitat types could mitigate loss for other species.

If these results are accurate, reducing future extinctions among bird species will require solutions to two problems. Reductions in greenhouse gas emissions will be necessary to prevent large-scale range loss and possible extinctions at higher latitudes. In areas closer to the tropics, controlling climate change still plays a role, but preventing habitat loss through expansion of protected areas and other conservation actions is more important in the immediate future.

The maps below show the likely landscape changes due to climate change and development, and the likely distribution of range reductions (click to enlarge).

(A, B) Patterns of change in land cover due to land-use and climate change by 2100. (C, D) The resulting potential impact for birds: the pattern of richness of species with projected range declines ≥50%. This represents the summed, current-day occurrence of qualifying species across a 0.5° grid. Patterns are given for the environmentally proactive “Adapting Mosaic” scenario (A, C), and the environmentally reactive “Order from Strength” scenario (B, D). Maps are in equal-area cylindrical projection. Colors in C and D vary from dark blue to dark red, and the legends provide labels for select colors along this continuous scale (minimum, ~1/3, ~2/3, maximum of data). From: Projected Impacts of Climate and Land-Use Change on the Global Diversity of Birds Jetz W, Wilcove DS, Dobson AP PLoS Biology Vol. 5, No. 6, e157 doi:10.1371/journal.pbio.0050157

Rare Crow Rediscovered

Researchers in Indonesia have refound a rare crow species, Banggai Crow (Corvus unicolor), that had been considered extinct.

The Banggai Crow was believed by many to be extinct until Indonesian biologists finally secured two new specimens on Peleng Island in 2007. Pamela Rasmussen, an MSU assistant professor of zoology and renowned species sleuth, provided conclusive verification.

An ornithologist who specializes on the birds of southern Asia, Rasmussen studied the two century-old specimens known as Corvus unicolor in New York's American Museum of Natural History. She compared them to the new crow specimens in Indonesia's national museum, to lay to rest speculation that they were merely a subspecies of a different crow. The more common Slender-billed Crow, or Corvus enca, also is found in the Banggai Islands, and likewise is all black.

Apparently eye color is a significant characteristic for differentiating the two species, in addition to the morphometric analysis that Rasmussen performed on the specimens.

So instead of being extinct, the Banggai Crow is simply critically endangered. Like other rare species, it faces a multitude of threats (and potential threats), primarily habitat loss and hunting. With a bird species rare enough to be thought extinct, the collection of new specimens will always raise some eyebrows. At least in this case we know that there are still living Banggai Crows since some birders have since found more in the same area. As long as some members of the species are alive, there is still hope for keeping them that way.

Box Turtle

Here is a box turtle from Brigantine:

Box turtles have a way of always looking slightly disgruntled. Perhaps it is because I only see them when I disturb them from some activity, such as crossing a path.

I took this photo back in August. It is one of many that have languished on my hard drives without being processed. Like the lighthouse photo, I took it shortly before my laptop's screen stopped working and needed repair. I will post a few more of these periodically in the next few weeks.

Nobel for Natural Resources

This may have been lost in the attention given to a more prominent prize and its recipient. Half of this year's Nobel Prize in Economics was awarded to Elinor Ostrom for her work on the distribution of natural resources.

Ostrom has studied the "tragedy of the commons," the notion that if a town has a common pasture on which everyone can graze sheep, the land will be overgrazed, making it less useful for everyone. Ostrom found that in a wide range of such settings -- such as shared fisheries, forests and water supplies -- people form voluntary arrangements to govern use and prevent overharvesting. That applies, she has found, even in the absence of a powerful centralized authority.

That has deep implications for how to help poor countries develop. If an aid agency were to build an irrigation system in a distant location that must be shared by different communities, it may need to establish whether those communities have a history of cooperating to share scarce resources, rather than expecting such restrictions to be enacted by fiat.

Sharing of natural resources is of course not just a problem for developing countries and not just a problem for human economies. Even in the United States there are ongoing conflicts involving water usage in western states, the interests of coal companies versus residents' drinking water from Arizona to Appalachia, and declining fisheries. There are also difficulties with distributing resources to meet both human and animal needs. Ongoing fights over habitat for owls and salmon in the Pacific Northwest are but two examples. As the climate changes and the world's population grows, the proper division of natural resources will come into even greater prominence. It is important that we have economists and other scholars studying how best to meet these challenges.

The Nobel committee awarded President Obama this year's Peace Prize with the hope that the United States would take "a more constructive role in meeting the great climatic challenges." Two years ago, it awarded the Peace Prize to the IPCC and Al Gore for their work in studying and promoting the threat of climate change. Those two awards, combined with this year's Economics Prize, seems like a signal that the Nobel committee is taking environmental issues very seriously. I wish American leaders would do the same.

Update: Here is Grist's take on the award.

Intoxicating Insects

Back in August, Bug Girl posted a call for participants to trap hornets and yellowjackets. The USGS is trying to develop survey techniques for these insects that could be repeated on a large scale. For this project, volunteers were asked to fill a clear plastic bottle partway with beer or fruit juice and leave it hanging for three weeks in an area that hornets might visit. (You can read the details at Bug Girl's Blog linked above.) I hung my beer trap over one of the gardens and then mailed the specimens to the USGS. The beer I used was Lord Chesterfield Ale; I wanted something that would be cheap but drinkable.

Sadly, the brew only attracted a single yellowjacket and a sweat bee. The yellowjacket was a German Yellowjacket (Vespula germanica), the insect pictured below. Kaufman's insect guide notes that this introduced species has become a pest due to its tendency to nest in walls. It is also an unwelcome guest at picnics and barbecues. When not scavenging the food and trash of humans, these yellowjackets prey on insects, including some pest species. Live yellowjackets should be treated with caution since they can be aggressive and have a painful sting; this one was pretty harmless.

Although this trap was short on Hymenopterans, it had captured plenty of other insects. Most were tiny flies or gnats, too small for me to identify and even difficult to separate from each other without damaging the specimens. There were also several larger flies, one of which was quite big. The lump in the top right of the photo below is a mass of tiny flies held together by the moisture. I think the fly on the lower right is a house fly (Musca domestica) and the one on the lower left is a Tachinid (family Tachinidae). Tachinids parasitize other insects by laying eggs on them. When the eggs hatch, the larvae feed on the host insect, killing it in the process.

In that photo you can also see a moth, which is shown in more detail below. Since the wings have been curled by the moisture and most of its markings dissolved, it would be impossible for me to identify the species.

There was also a second larger moth, pictured below. The wings on this specimen show more of their shape, but unfortunately they too have lost their markings. One detail I found interesting is that the body on this moth seems significantly longer than its wings. Most of the moths I have been seeing show the opposite.

The beer trap also caught a cranefly. This is not a Giant Cranefly like the ones I posted last month, but I am not sure of the species.

This was a fun exercise, and I am glad that I participated. Perhaps if I had hung my trap a week or two sooner, it would have collected a few more of the target species. I noticed more bees and wasps around that garden in the weeks prior to hanging the trap than in the three weeks after. In any case, I would encourage readers to participate if the opportunity comes up again.