Thursday, April 28, 2011

Good Radiation

This video is from cadamole, the artist who wrote A Biologist's Mother's Day Song. I'm pretty much loving everything this guy posts and this rap about public radio is no exception. As I do a lot of tedious lab work I listen to a lot of NPR, if you do too then you will love love love this!

Friday, April 22, 2011

Happy Earth Day!

Happy Earth Day, ya'll!

Today, April 22, marks the birth of the environmental movement in 1970 in the U.S. During the early 1960's the attitudes of many Americans concerning the environment began to change. No longer were they thinking of the Earth's natural resources as limitless and using them as without consequences. This was particularly evident with the controversy that erupted after the publishing of marine biologist Rachel Carson's Silent Spring in 1962. When the Apollo astronauts photographed the Earth from space in 1968 the image brought home the fragile nature of the planet. Close on the heals of this event was the 1969 industrial accident in Ohio Cuyahoga River, where the industrial runoff caught fire and spurred many to action. This action resulted in the U.S. Congress passing the National Environmental Policy Act (NEPA) that established a national policy that encouraged harmony between man and nature. The U.S. involvement in the war in Vietnam added yet another layer, no so much to the environment itself but instead challenging the status quo on public policy and human rights. When you boil it down, the environmental movement includes conservation and green politics and actions. It advocates for sustainable management through public policy and individual behavior. And while there is no central organizing force behind it there are various organizations, in a range of sizes, that promote awareness, work with local and national figures, and educate the public through events.

Earth Day started with Gaylord Nelson, a U.S., senator from Wisconsin. Nelson was a conversationalist who had witnessed the ravages of the massive 1969 oil spill in Santa Barbara, California, and was someone who knew how to inspire the youth of America into action. In late 1969, he announced there would be a national "environmental teach-in," which resulted in 20 million Americans taking to the streets, parks, and auditoriums to protest against oil spills, industrial pollution, raw sewage, toxic dumps, pesticides, habitat loss, and other environmental degradation. It was the first Earth Day event. It was a nationwide demonstration for concern for the environment involving thousands of schools and communities. It was followed by the creation of the U.S. Environmental Protection Agency (EPA) in 1970, then the Clean Air Act, then the Clean Water Act in 1972, and the Endangered Species Act in 1973. During this time new groups such as Greenpeace, formed in Canada in 1971, and existing organizations such as The Nature Conservancy, formed in 1951, the Sierra Club, and the National Audubon Society adopted and/or promoted these principles as well as bringing legal action against companies that destroyed the land and resources. By the late 1980's, individuals had gotten into the movement by living greener and establishing things like local recycling programs. Earth Day had a resurgence in the 1990's, this time it was global, with the participation of 200 million people and 141 countries. In 1992, at the United Nations Conference on Environmental Development (UNCED), or Earth Summit, an unprecedented number of governments and NGO's agreed on a program to promote sustainable development, and then U.S. President Bill Clinton was prompted to award the Medal of Freedom (the highest honor given to civilians in the U.S.) to Gaylord Nelson. In the early 2000's the environmental movement focused on global warming and clean energy, using the Internet or organize activists. Today we find ourselves embroiled in controversy once again with climate change deniers, lobbyists, reticent politicians, and a disinterested public. But concern by many for the environment and especially interest in green energy is keeping the movement alive.

Want to know more about Earth Day events near you, no matter what part of the world you live in? Check out the EPA's Earth Day page:

Here are a few more Earth Day websites I recommend checking out:

Learn more of the history behind Earth Day here:

(image from

Tuesday, April 19, 2011

A Catchy Tune

image from the Daily Mail, story linked below, credit to Alamy
 I heard a song in the car earlier today and now it's stuck in my head. I've been silently, and sometimes no so silently, singing it all day. So imagine my surprise when I was flipping, or rather clicking, through the most recent issue of Current Biology and this study all about the cultural transmission of humpback whale song caught my eye.

Cultural transmission. Put simply it is the social learning of information or behaviors within members of a species. In the animal kingdom you can find it in several large groups including cetaceans (whales and dolphins), birds, and primates. It can happen in a couple of different ways. Cultural traits can be passed vertically from parents to their offspring. They can be passed obliquely from older nonrelated individuals to younger individuals. And they can also be passed horizontally between unrelated individuals close to or within the same generation. Kinda makes sense right? I mean, where did you get your information as you grew up and where do you get it now?

The study for today's post takes a look at male humpback whales (Megaptera novaeangliae). This species is wide ranging, living in polar and tropical waters all over the globe, and they are known to migrate between northern and southern latitudes with the climatic cycle usually for feeding and reproduction. Humpback whales live in groups and are protective but not thought to be territorial. Both males and females will vocalize, but males produce long, loud, and often complex songs that function in sexual selection. It is known that whales within a population will sing the same song which will slowly change over time. This study looks at the horizontal transmission of these songs over the ocean basin.

Before discussing a paper about whale songs it is probably goon to note that the sounds of a song are arranged in a nested hierarchy: "themes" contain a number of repeated "phrases" which consist of a string of individual "units." In this study, the researchers picked field locations that corresponded to the multiple migration routes and breeding grounds within the western and central South Pacific region (northeastern Australia, New Caledonia, Tonga, American Samoa, the Cook Islands, and French Polynesia). Over an 11 year period they recorded humpback whale songs mostly using hydrophones suspended from boats. Then they viewed the songs as spectrographs so that they could look at each unit in the song clearly and then transcribe it based on the visual and aural qualities of the sound. The recorded sounds were classified and analyzed, comparing the similarity of songs and grouping all songs of the same type or themes together. The identified song types were grouped into six different lineages with color: pink, black/gray, blue, red, yellow, and green. When a song had comnpletely evolved and the orignial themes were replaced they were renamed/recolored. This made it easier to track the movement, evolution, and splits in song type between populations.

The study points out that at any one time males within a population show a strong conformity to a single song type containing the same themes sung in the same order. The pattern of the song evolves from year to year but all singers maintain conformity. When analyzing the songs they found that four new songs originating in eastern Australia gradually spread eastwards so that within two years the whales in French Polynesia were singing the same song. That is pretty fast over a really large area. Considering that, during the breeding season (July-October), there are several breeding groups where interchange is uncommon, what is going on?  The direction of the song transmission may be the detail that answers this question. The songs appear to have changed and radiated consistently from west to east in a series of cultural waves. One possible explanation for this directionality is that the eastern Australian population is the largest in the region and so its influence on the other populations is greater than the influence of the other populations on it. Another explanation is the migration. Males from different populations encounter each other along shared migration routes where they hear and learn each other's songs. Previous studies have shown that the eastern Australian population songs rapidly change, within two or three months, and so migratory routes would not need to overlap extensively and minimal contact would be required for song learning.

Overall, this study is a wonderful example of cultural transmission over a vast geographic area. The rate of change and the vocal linkage between populations is pretty incredible. Now I just need go get my next cultural wave of information to get this song out of my head.

Read the article here:
Garland, Ellen C. et al. (2011) Dynamic horizonal cultural transmission of humpback whale on at the ocean basin scale. Current Biology: 21, 1-5. (DOI: 10.1016/j.cub.2011.03.019)
The article and supplementary content includes audio recordings.

Visit the Whalesong  Project:

After some searching I found that this article has been picked up by some major news outlets, particularly in Australia:

Friday, April 8, 2011

Resistant to Base

You're gonna have to face it, it's resistant to base!

Moving at a Snail's Pace

This post is about slime. Well, it's about moving around in slime. *squish*

Mollusca, or mollusks, is a large and highly diverse phylum of invertebrate animals. Within this phylum is the Class Gastropoda, or gastropods, which include snails and slugs. Generally, gastropods, specifically snails, have an asymmetrically spiral (coiled on one side) shell that functions as a portable retreat. Slugs are almost identical to snails except they lack a shell. The snail and slug body consists of a head, foot, and visceral sac/hump, and mantle (pallium). The head includes a mouth surrounded by one or two pairs of tentacles which often carry eyes and a pharynx containing coarse or fine teeth on the radula (like a tongue). The foot is the main locomotive organ and is usually the part that is visible outside of the shell. On the sole of the foot are mucus glands that secrete the slime that the gastropods crawl on.The visceral sac contains most of the inner organs and the mantle is a tissue fold covering it.

Though snails and slugs have no external extremities they are quite capable of moving around in their environment. Understanding this movement has been of interest to scientists and engineers for some time, even inspiring new classes of robotic movement and adhesive locomotion. It is known that a series of pulses of muscle contraction and relaxation traveling along the central part of the foot's ventral surface allows the snail to move forward, and only forward in terrestrial gastropods. The pulses of muscles are called pedal waves, the regions of the foot between pedal waves are called interwaves, and the distance between the two is called the wavelength. When these waves interact with the mucus secreted by the gastropod propulsive forces are transmitted to the ground. In describing snail locomotion, the number of waves is classified according to their number and direction. They are classified as a single train of pedal waves (monotaxic) or as a two (ditaxic) or four (tetrataxic) series of waves. It is also known that the crawling speed is directly proportional to the speed and frequency of the pedal waves.

A 2010 study in the Journal of Experimental Biology takes a look at the mechanism by which the propulsive forces are generated during gastropod locomotion. To accomplish this the researchers used a newly developed force-cytometry method where they calculate the spatial and temporal distribution of pedal forces from measurements of the deformation produced by the snail when it contacts a surface of known elastic properties. This allows them to study the movement is great detail. They can measure the horizontal traction stresses to the surface underneath the snail/slug without any interference with the animal's body. Neat. The study also analyzes the kinematics (motion without reference to the forces causing it) of the pedal waves and its significance of the generation of traction force. They did this to find the relationship between speed/wavelength and velocity, to determine if the waves maintain a constant speed/wavelength, to find how the snail accelerates and decelerates, and to see if a change in speed is accomplished by increasing the number of waves or by varying the speed/wavelength.

Fig. 1. from the paper showing the ventral surface of the banana slug
That all sounds very...complicated. So how do you measure the pedal waves of a snail's foot? If you know any biomechanists then you know they like to do two things - put animals on treadmills and put animals on transparent surfaces. In this case they tested banana slugs (Ariolimax californicus and A. buttoni), grey field slugs (Deroceras reticulatum), and garden snails (Helix aspersa) by placing them on transparent surfaces, illuminating them, and then recording them crawling with digital cameras. Turns out that if you illuminate the body in different ways you can get different information about movement. Add all of those ways together and you get a 3D reconstruction of the snail's foot as it moves.
The researchers found that when a snail/slug moves forward there are alternating pedal wave and interwave regions propagating from the tail forward to the head, but the interwaves remain stationary with respect to the ground. That result wasn't all that surprising, and agreed with previous studies. When they looked a little closer at the high-resolution images they found that the organization of the waves was not symmetrical and did not move at a constant speed. They observed steady wave acceleration followed by abrupt deceleration, a variable speed of pedal waves which modulated the magnitude of stresses under each wave. This was unexpected and observed in more than one of their test species, suggesting that the pattern is mechanically relevant to locomotion. They also found that the net forward force was generated beneath each stationary interwave. This is where the animal is pressing the foot against the ground and then pulling it backwards, propelling the body forwards. The foot is actually lifted during the pedal waves. Another result showed that that the crawling speed increased with pedal wave frequency. Not all that surprising, have more waves then move faster. And the mucus, we can't forget the mucus. This study's experiments showed that the slugs were able to move themselves over very thin threads of mucus without changing the pedal wave pattern or frequency. This suggests that the amount of pressure applied by the foot doesn't really matter for propulsion. Considering the rugged surfaces that snails and slugs move on that is not all that hard to believe.

The take home message? Mucus is helpful but it is the muscle movements that allow snails/slugs to crawl.

Read the study here, and there are videos in the supplemental materials:
Lai, J. H., J. C. del Alamo, J. Rodriguez-Rodriguez, J. C. Lasheras (2010) The mechanics of the adhesive locomotion of terrestrial gastropods. Journal of Experimental Biology: 213(22), 3920. (DOI: 10.1242/jeb.046706)

Get in Shape

Lately I've been reading papers on leaf morphology, and in the grand art of being lazy I decided to post about a paper I've already read rather than reading a whole new one.

I think that reading a paper about leaf morphology is kinda difficult if you don't know the basic parts of a leaf, and although this paper doesn't get into the itty-bitty differences in leaf structure I'm still gonna go through some of the basics. This is a leaf:

It consists of a (usually) flat photosynthetic portion called the blade where the very tip is called the apex, the edges the margins, and includes both a midvein and lateral or net veins. The margins of some leaves are serrated or have "teeth" with the low, in-between areas called the sinuses. At the base of the leaf the blade is attached to a supportive stalk called the petiole. Where the petiole and the stem meet is the stipule.

Morphology refers to the study of the forms of things and the relationships between their structures. In botany, leaf morphology is simply the characterization of leaf shape. The traits that you see on plants are determined by a combination of genetic heritage (genotype) and the capacity for a single genotype to respond to environmental variation (phenotypic plasticity). There has been quite a lot of research into the roles of genotype and plasticity in order to figure out how an organism responds to change. Studies such as these typically grow plants in a common garden experiment where all of the individuals are grown under exactly the same conditions so as to see what traits are different. These types of experiments show that in most species both plastic and genetic factors are important for a number of plant functions such as stomatal distributions, photosynthetic efficiency, leaf area, water availability etc. However, little is known about the plastic response of some leaf traits to temperature.Why does that matter? In terms of global climate change it is important to know both how plants responded to temperature in the past, using fossilized plants, and how they are responding to changing temperature now. And because many of these traits are plastic they can tell us a lot about rapid climate change. For example, it is known that in colder climates plants have more highly dissected leaves, meaning they have a low shape factor and a high compactness and perimeter ratio, and that many species show a temperature effect on leaf shape.

A paper from 2009, published in PLoS ONE, takes a look at leaf size and shape in Red Maple (Acer rubrum) growing in contrasting climates. They started by collecting seeds across a broad temperature gradient, across the eastern U.S. and Canada. Then two common garden experiments were set up in Rhode Island and Florida. These were common garden experiments in that they had the same set up in terms of plot layout, plant spacing, etc. but as they are in different locations there are differences in soil composition, precipitation, etc. Once the plants had grown then two leaves per plant were collected and the petioles removed, then they were dried, pressed, and photographed against a black background. The researchers used Photoshop to analyze their leaf images. They measured/counted the number of teeth, leaf area with teeth, and leaf area without teeth. They also measured a range of leaf size and shape variables using a program called ImageJ (very useful freeware from NIH that I use all the time). There were three categories of variables:

1. Leaf Dissection - Shape Factor: This was calculated as 4pi times the leaf area divided by the perimeter squared.
2. Compactness: This was calculated as the perimeter squared divided by the area.
3. Perimeter Ratio: This was calculated as the perimeter divided by the internal perimeter. The internal perimeter being without the teeth.

In this study, phenotypic plasticity was used analogously with growth site, and they found that growth site explained 5 to 19% of the variance they observed for traits related to the number of teeth on a leaf and the leaf dissection. They also found that seed source accounted for 69 to 87% of the variance. The plants from cold climates had more teeth, but smaller teeth, and were more highly dissected. The researchers concluded that while the size of the teeth is probably due to genetics, leaf dissection and tooth number likely respond plastically to their environment. These results are consistent with other studies that found a functional link between leaf teeth and climate. As the trees studied here were only grown for two years before sampling, this study shows that plants can respond quickly to environmental change. That is good news for paleobotanists who study leaf morphology in fossilized plants, it can give them an idea of the environmental conditions with greater resolution. However, it is important to note that plasticity isn't the only process that determines the distribution of leaf traits. Other process operate on slower timescales and include evolutionary changes within a population and species. Also, this study does not look at environmental factors such as the concentration of atmospheric carbon dioxide and the UV-impact plants receive.

If you would like to read this paper you can find it for free through PLoS ONE:

Royer, Dana L. Laura A. Meyerson, Kevin M. Robertson, and Jonathan M. Adams. (2009) Phenotypic plasticity of leaf shape along a temperature gradient in Acer rubrum. PLoS ONE: 4(10), e7653. (DOI: 10.1371/journal.pone.0007653)

(images from and, respectively)

Tuesday, April 5, 2011

The Photosythesis Rap

Many of my botanist friends found this song/video to be entertaining. I'm sure you will too.

Cleaning Station Alpha

You're a large wild animal. You itch. You scratch. You attract little critters that you can't reach. What do you do?

You are a small wild animal. You search. You hunt. You need to find those juicy morsels to keep your little belly full. What do you do?

Ectoparasites are any parasites that live on the exterior of another organism. They are pests and can be nuisances and detrimental effects for large animals. However, a mutualism has evolved between large pest-riddled animals and smaller organisms which feed on these pests. You are probably familiar with pictures of small birds sitting on large mammals. These birds get the benefit of an ectoparasite meal and the large mammal gets the benefit of no ectoparasites. But did you know that this type of mutualism doesn't just exist in terrestrial ecosystems?

A wide variety of small marine organisms clean external parasites (and dead skin) from other marine organisms (clients), typically other fish. These cleaners include wrasses, gobies, shrimp, cichlids, etc. Some species of cleaners will even set up a cleaning station where client fish stop in, partake of the cleaning service, and then swim away. Studies have shown that reef fish will actively visit cleaner fish to have parasites and dead or infected tissue removed. These studies typically investigate the station itself, including which species sets it up and which species partake of its services, or the behavior of the fish at the station, what keeps the cleaner fish honest and not taking little bites of healthy client tissue. There have also been several studies in various systems that have failed to show, quantitatively, any benefit to the clients, suggesting that cleaner fish are "behavioral parasites." In other words, they exploit the sensory system of the clients to obtain food, they do not increase the fitness of the client.

A new(ish) paper in the journal PLoS ONE investigates the interaction of cleaners and pelagic shark species at a seamount. Seamounts are hotspots of biodiversity in the open ocean, acting as stepping-stones for marine species to spawn and dispense their larvae. They also serve as important habitats for visiting large marine vertebrates, such as sharks, potentially acting as social refuges. This study looks at the pelagic thresher shark (Alopias pelagicus). This shark reaches 12 feet (365 cm) long, most of which is a long tail fin, and inhabits warm and temperate offshore waters circumglobally. It is known that sharks that are infected with ectoparasites suffer from a variety of health consequences including anaemia, retarded reproductive organ development, reduced respiratory efficiency, debilitating skin disease, and infections. Therefore, it is likely that visiting a cleaning station would be beneficial to the sharks.

This paper quantified the behavioral interactions between pelagic thresher sharks and cleaner wrasse to test if cleaners selectively forage on specific areas of shark clients and if shark clients modify their behavior to facilitate inspections from the cleaners. The researchers sampled fish at the Monad Shoal, in the Visayan Sea, due east from Malapascua Island, Cebu, in the Philippines. It is a seamount that rises 820 feet (250 m) from the sea floor with the top forming a plateau at 50 to 65 feet (15 to 25 m) depth. They selected five cleaning stations and set up remote video cameras to observe the behaviors of the fish. They identified the areas, or "patches," of a shark's body known to harbor high concentrations of parasites to see which patches the cleaners were inspecting the most. They categorized the behaviors in order to differentiate the behavioral patters of the sharks while they interacted with the cleaners including swim speeds and direction of locomotion and posing patterns.

The researchers found that the cleaners showed preferences for foraging on specific patches of a sharks' bodies with the highest percentages of inspections occurring on the pelvis, pectoral fins, and caudal fin. These results, particularly the high concentration of cleaning in the pelvic region, likely reflect the distribution of ectoparasites on the bodies of the sharks. There was no preference for time of day or shark sex, but there was a positive correlation between the amount of time a shark spent at a cleaning station and the number of inspections it received. The authors suggest that sharks that spent more time at a cleaning station harbored more ectoparasites. A head-stand or tail-stand posing behavior is classic to reef fish clients at cleaning stations that act as signals to solicit a cleaning interaction, but require fish to pump their gills or lie still to be cleaned. However, the thresher shark, like most oceanic sharks, is what is called an obligate ram ventilator, meaning that it must constantly swim to maintain oxygen ventilation, or to "breathe." To get around this problem and still advertise they they want the cleaning service the sharks performed a behavior called "circular-stance-swimming." The shark slows its routine swim speed while assuming a head-up swimming attitude and lowering of the caudal fin and then performs slow circular swims in/around the cleaning station.

This study suggests that cleaner wrasse play an important part in the structure of seamount communities. The cleaners show selective behavior in cleaning high parasite areas which may make them more attractive to the clients. Pelagic thresher sharks regularly visit the cleaner stations and even modify their behavior to facilitate cleaning. Overall, a very interesting interaction.

Here is the paper - and it is from PLoS ONE so it is free!
Oliver, Simon P., Nigel E. Hussey, John R. Turner, and Alison J. Beckett. (2011) Oceanic sharks clean at coastal seamount. PLoS ONE: 6(3), e14755. (DOI: 10.1371/journal.pone.0014755)

(images from and , respectively)

Friday, April 1, 2011

Batting a Billion

Did you know that 2011-2012 is the Year of the Bat? Thanks to classic literature and popular culture, bats are thought to be nocturnal, creepy, winged rats. Probably every fear people have concerning bats is based on centuries of myths and misinformation. As part of my what-is-becoming-typical subject introduction I thought I'd give some facts and dispell a few of the myths about bats with a little round of True or False. As I plan to present a paper here and not just a bunch of bat facts I'll try to keep to some of the most popular myths and at the end of this post I'll have some links where you can find out more information.

True or False?: Bats are mammals.
Bats are flying mammals belonging to the order Chiroptera. There are more than 1,100 species (that's 1/5 of all mammals!), including the world's smallest mammal, a bat the size of a bumblebee.

True or False?: Bats are blind.
Actually many bats have very good eyesight. However, because many species are nocturnal (active at night) they have an extra sense that helps them to navigate and find food: echolocation. They send out sound which bounces back off of objects and creates a sort of map for the bat.

True or False?: All bats feed on blood.
Well, mostly. Admittedly there are three species of vampire bat: the Common Vampire Bat (Desmodus rotundus), the Hairy-legged Vampire Bat (Diphylla ecaudata), and the White-winged Vampire Bat (Diaemus youngi); all of which are found in Latin America. But don't worry, they don't require much blood and typically like to feed on livestock. More than two-thirds of bat species are primary predators of night-flying insects, this includes agricultural pests and many insects humans find to be particularly disruptive or annoying. A single bat can eat up to 1,000 mosquito-sized insects in a single hour! The other third of bat species feed on the fruit and nectar of plants. As such, they serve as pollinators and seed dispersers for many plant species. A small percentage are also known to eat fish, frogs, mice, birds and/or other small vertebrates.

True or False?: Bats are found everywhere.
Close but no. Bats are a very diverse group that take advantage of a wide variety of habitats, but they do not inhabit extreme desert and polar regions.

True or False?: Bats live in caves.
You can find many bat species living in caves. This is because one of the most basic requirements for bat is a safe roost. As such, bats can be found living in almost any conceivable shelter, from caves to buildings to leaf cavities and even in animal burrows. As their habitats shrink, more and more species, and individuals, can be found living in buildings. Building bat houses, the same concept as a bird house, is a backyard conservation technique that is catching on with the public. (Learn how to build you own bat house here:

The questions that I've listed here are not only some of the most popular concerning bats, they are also directly related to today's topic. A new Policy Forum paper published in Science this week takes a look at bat conservation from the aspect of their economic importance.

It is known that White-nose Syndrome (WNS) and the increased development of wind-power facilities are threatening populations of bats in North America. WNS is a fungus (Geomyces destructans) that infects the skin of cave-dwelling bats while they hibernate, particularly around the nose, ears, and wings. It is associated with a high mortality rate and is estimated to have killed over a million hibernating bats in more than 15 U.S. states and 2 Canadian provinces. Little Brown Bats (Myotis lucifugus) are sustaining the highest mortality rates, showing a 93% decline in 23 caves at the epicenter of the WNS outbreak. Other species affected include the Big Brown Bat (Eptesicus fuscus), Northern Myotis (Myotis septentrionalis), Tri-Colored Bat (or the Eastern Pippistrelle, Pipistrellus subflavus), Eastern Small-Footed Myotis (Myotis leibii), and Indiana Bat (Myotis sodalis).

Our growing concerns about climate change mixed with our desire to break our dependance on oil have resulted in the construction of more wind turbines. As a source of alternative energy wind turbines are a wonderful thing. However, for species of migratory tree-dwelling bats they are a flight, and life, hazard. In North America, these species include the Eastern Red Bat (Lasiurus borealis), the Hoary Bat (Lasiurus cinereus), and the Silver-haired Bat (Lasionycteris noctivagans). Other species that are ssusceptible to wind turbines include the Tri-colored Bat (L. subflavus), the Little Brown Myotis (M. lucifugus), and the Big Brown Bat (E. fuscus), species names that should sound familiar after reading about WNS. Included in this list of affected species includes bats with a relatively small range sizes, the Mexican Free-tailed Bat (Tadarida brasiliensis) and the federally endangered Indiana Myotis (M. sodalis). High numbers fatalities in species with small range sizes has a greater impact on the survivability of the species than the same number of fatalities in populous, large-range species. It is still unclear why these species are so susceptible to wind turbines. There is no continental-scale monitoring programs for assessing wildlife fatalities caused by wind turbines, but it is predicted that by 2020 an estimated 33,000 to 111,000 bats will be killed by wind turbines just in the Mid-Atlantic Highlands of the U.S.

This article focuses on these two sources for declining bat populations, leaving out sources such as habitat degradation. The numbers of bat fatalities are, in and of themselves, pretty staggering, but many people in political and policy making positions still consider it an academic interest rather than an economic problem. That is where this article becomes particularly interesting. In fact, the economic consequences of losing so many bats could be substantial. One example the authors use is the Big Brown Bat (E. fuscus). A single colony of 150 bats in Indiana as been estimated to eat nearly 1.3 million pest insects per year. Think about it: That is one relatively small colony of bats eating a whole lot of insects. Other estimates have a single Little Brown Myotis (M. lucifugus) consuming 4 to 8 grams of insects each night. Doesn't sound like much, but if you extrapolate that from one bat to one million bats that is 660 to 1320 metric tons of insects. This is a huge disruption to the population cycles of agricultural pests, and to say that bats are unimportant is just ignorant. 

The paper goes on to discuss the economic importance of bats in agricultural systems, estimating the value of the pest suppression services provided by bats. Previously published estimates have the value at anywhere from $12 to $173 per acre, with a likely value at $74/acre in a cotton-dominated landscape in south-central Texas. The authors here took these values and extrapolated the estimates to the entire United States. They estimated that the value of bats to the agricultural industry at between $3.7 billion and $53 billion per year with a likely value of approximately $22.9 billion per year. This cost does not include any downstream impacts of bat loss such as the impact of pesticides, secondary predation, and the predator release of insect populations.

A figure describing the worth of bats. Yellow being low cost to red being high cost.
 In terms of policy, the authors suggest that wait-and-see approach to the issue of widespread declines of bat population is unacceptable as the life histories of these mammals suggest that population recovery is unlikely for decades or centuries, if at all. They suggest management actions to restrict the anthropogenic spread of WNS, taking additional steps toward developing improved diagnostics to detect early stage infections and fungal distribution, investigating biological or chemical control of the fungus, increasing disease resistance through habitat modification, potentially culling infected bats, altering wind turbine operations during high-risk periods for bats, and continued research into these problems.

Here's the article:
Justin G. Boyles, Cryan Paul M., McCracken Gary F., and Kunz, Thomas H. (2011) Economic Importance of Bats in Agriculture. Science: 332 (6025), 41. (DOI: 10.1126/science.1201366)

Description of bat species from the Smithsonian National Museum of Natural History:
Info on bats from the Natural Science Research Laboratory at the Museum of Texas Tech University:
The Year of the Bat website:
From Boston University's Bat Lab:
From the Museum of Palentology at UC Berkeley:
A list of academic "bat labs":

From Bat Conservation International:
Bats and Wind Energy Cooperative (BWEC):
Video and information from Boston University about bats interacting with wind turbines:
U.S. Department of Interior, US Fish and Wildlife Wind Turbine Guidelines Advisory Committee:

Buzbee's Bathouse Page:
Info from the U.S. Fish and Wildlife Service:
From the Organization for Bat Conservation:
USGS National Wildlife Health Center WNS Page:
The National Speleological Society's WNS Page:

Bat Conservation International:
Organization for Bat Conservation:
Bat Conservation and Management, Inc.:
Lubee Bat Conservancy:
Bat World Sanctuary:
Bat Conservation Trust (in the UK):
The Warwickshire Bat Group (UK):
The Norfolk Bat Group (UK):

(image from
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