The (Mythical?) Snipe

So who's this hiding from the camera?

Wilson's Snipe (Gallinago delicata), Potter Marsh, Anchorage, AK 8/10/2012

This is a Wilson's Snipe (Gallinago delicata), a rather large sandpiper with a preference for wet meadows and shallow wetlands. They used to breed here in Illinois, but in recent decades that's become an extremely rare event. However they still migrate through, and I saw my first one of the year earlier today.

Here's one that's not hiding -- you can see the long bill, on the long side even for shorebirds, and the stripes that act as camouflage in the deep grasses they prefer to live in.

Wilson's Snipe (Gallinago delicata), Potter Marsh, Anchorage, AK 8/3/2012

Now, if you grew up in the Boy Scouts, or watching Cheers and the second incarnation of Star Trek, you may be thinking "What's wrong with this picture?" After all, everyone knows that there's no such thing as Snipe. I was told that by a junior-high shop teacher, and campers everywhere used to be introduced to Snipe hunts, where you're handed a pillowcase and told to go out in the woods at night and make weird noises. On the other hand, if you're a birder, or a bird hunter, you smile when you hear that claim. When I go looking for Snipe, I find them.

Sadly, the tradition of Snipe hunting seems to be dying out. These days, I rarely if ever find a student who's even heard of snipe.

Those long bills are used to probe into soil or mud for invertebrate prey, either on land or in the water. This means that the type of soil is going to be as important as the amount of prey it contains when the bird's trying to decide where to forage. Green, et al. found that females foraged close to their nest on dry ground when the soil was moist and prey was plentiful, but moved farther away when things dried out. (1) They also found that the preferred prey type varied with how wet the summer was, although they didn't state whether this was a result of foraging conditions or an actual preference for one or the other.

This sort of preference may explain the findings of McCloskey & Thompson, who found that females wintering on the Texas coast predominated in wet meadows with plenty of vegetation whereas males predominated in more open wet environments. (2)

That's fancy findings for a species that many people insist doesn't exist!

(1) Green, R. E., Hirons, G. J. M., & Cresswell, B. H. (1990). Foraging habitats of female common snipe Gallinago gallinago during the incubation period. Journal of applied ecology, 325-335.

(2) McCloskey, J. T., & Thompson, J. E. (2000). Sex-related differences in migration chronology and winter habitat use of Common Snipe. The Wilson Bulletin, 112(1), 143-148.

The Moths Are Coming!

My first little (outdoor) moth of the year:

Epinotia zandana, Van Patten Woods FP, Lake Co, IL  3/30/2014

This, I believe, is Epinotia zandana, one of the Tortricid moths. This is a big family of tiny critters, with approximately 10,000 species. (That's more tortricid moths than mammals in total!) Their even tinier caterpillars live on various plants, many of them of considerable economic value. As a result, quite a few are considered pests, with the Codling Moth (Cydia pomonella) shown here as an example:

Codling Moth (Cydia pomonella), Zion, Lake Co, IL 7/26/2012

Codling Moth caterpillars eat apples, from the inside out. As a result, apple growers spend millions of dollars a year trying to keep them out of their orchards, but despite that, they've colonized most of the world.

On the other hand, E. zandana caterpillars feed on hawthorn leaves, and have probably been doing so for thousands of years with no observable negative impacts. (On a population level, that is - the leaf being eaten would have a different opinion if it were capable of such, I'm sure.)

Given the status of many of these moths as pests, it's not surprising that some of them are well-studied. On the other hand, species that aren't considered pests are barely noticeable in the literature -- a Google Scholar search for E. zandana yields 10 citations, 3 of which refer to better ways to catch Tortricids (1,2,3) . Another one is simply a review and checklist of lepidoptera of Maine (4) . A similar search for the Codling Moth yielded 100 pages!

I often tell my students, the cheap way to discover a new species is to learn a bunch about some obscure group of invertebrates and then head down to the Field Museum and spend a few days in the back rooms looking through trays of specimens. Well, a fairly recent example of that was reported in 2002, when this species was first described (5):

Epiblema glenni, Zion, Lake Co, IL  7/21/2012

This is Epiblema glenni, another Tortricid. Despite all of the money and effort we've expended upon this group, there's still more mysteries than pests.

(1) Priesner, E., Reed, D. W., Underhill, E. W., & Bogenschütz, H. (1989). (Z, Z)-7, 9-Dodecadienyl acetate, sex pheromone ofEpinotia tedella clerck (Lepidoptera: Tortricidae). Journal of chemical ecology, 15(10), 2457-2464.

(2) Beroza, M. (1972). Insect sex attractant pheromones, a tool for reducing insecticide contamination in the environment†. Toxicological & Environmental Chemistry, 1(1-2), 109-134.

(3) Reed, D. W., & Chisholm, M. D. (1985). Field trapping of threeEpinotia species with (Z, Z)-7, 9-dodecadienyl acetate (Lepidoptera: Tortricidae). Journal of chemical ecology, 11(10), 1389-1398.

(4) Brower, A. E. (1983). A List of the Lepidoptera of Maine--Part 2: The Microlepidoptera Section 1 Limacodidae Through Cossidae.

(5) Donald J. Wright. 2002. A New Species of Epiblema previously confused with E. tripartitana (Zeller) and E. infellx (Heinrich) (Tortricidae). Journal of the Lepidopterists' Society, 56(4): 277-285.

A Beetle Out Of Water

First (outdoor) insect shot of the year:

Hydrobius fuscipes, Van Patten Woods Forest Preserve,
Lake Co, IL  3/29/2014

I think this is Hydrobius fuscipes, one of the water scavenger beetles of the family Hydrophilidae. Some members of this family, most likely including this one, undergo dispersal flights in the spring, (1) which would explain why this guy fell out of the sky right in front of me. Unfortunately for him, I suppose, he missed the water, landing on the boardwalk instead.

This species was part of a field study in Scotland examining changes to aquatic macroinvertebrate faunas in a mixture of temporary and permanent ponds. Jeffries found that even permanent ponds had a considerable turnover, which suggests that dispersal flights must be very important in maintaining a population of these beetles. Surprisingly, they also found that extinction rates were similar in temporary and permanent ponds, indicating that factors other than the loss of water were responsible for most local extinctions. (2)

Another interesting result throws a significant wrinkle into that story, though. Working in experimental tanks in Illinois, Resetarits found that another member of this family, Tropisternus lateralis, actively avoided colonizing tanks with fish in them. (3) This suggests that some of the colonization/extinction dynamic found by Jeffries in Scotland was based on interactions between species, in many cases interactions that took place generations ago, rather than the simple incidence models he was using. Trying to tease all of this apart is a tricky task indeed!

Biology is sometimes called a "soft" science. This is in contrast to chemistry or (especially) physics, which are "hard" sciences. This doesn't refer to difficulty, but rather to the degree that the field is dependent upon mathematical descriptions. While there are fewer mind-bending calculations in biology, there is no reason for a physicist to consider the ancient history of a photon. In biology, though, ignoring the evolutionary history of your subjects is bound to lead you astray, no matter how seductive your calculations may look.

(1) Landin, J. (1980). Habitats, life histories, migration and dispersal by flight of two water‐beetles Helophorus brevipalpis and H. strigifrons (Hydrophilidae).Ecography, 3(3), 190-201.

(2) Jeffries, M. (1994). Invertebrate communities and turnover in wetland ponds affected by drought. Freshwater biology, 32(3), 603-612.

(3) Resetarits, W. J. (2001). Colonization under threat of predation: avoidance of fish by an aquatic beetle, Tropisternus lateralis (Coleoptera: Hydrophilidae).Oecologia, 129(1), 155-160.

The Robins are Back!

Things are finally starting to warm up out there, and suddenly these guys are all over the place:

American Robin (Turdus migratorius), St. Louis Zoo,
St. Louis, MO  3/2/2012

This is, of course, an American Robin (Turdus migratorius), one of our most famous birds. They're well known for chasing worms across our nicely mowed lawns -- in fact, there's evidence that mowing actually makes their prey more visible, and mowed lawns are actually preferred for feeding in. (1) And here's a shot of one doing just that:

American Robin (Turdus migratorius), Illinois Beach State Park,
Lake Co, IL  5/19/2012

So, when the winter rolls in, and the snow's on the ground and the worms are down deep and the bugs are hibernating, then everyone knows that the robins head south for the winter, to return as the first sign of spring, right?

Well, not exactly! Apparently our breeding robins do head south for the winter, but if you wander the right forest preserves in the winter time, you'll likely see something like this:

American Robin (Turdus migratorius), Lyons Woods Forest Preserve,
Lake Co, IL  12/11/2012

This guy's hanging out in what looks like a Hawthorn tree, in Lyons Woods Forest Preserve, in December. And you can still find them in various locations around the area throughout the winter. Turns out they're winter visitors from even farther north, but either way, they can't be chasing worms!

In fact, they're mostly eating fruit -- this guy's sitting in his favorite diner at the moment. Quite a few birds that we think of as mostly insectivores turn to fruit in the winter, including many of the thrushes, Yellow-rumped Warblers, Eastern Kingbirds, and even Tree Swallows. Others, including Cedar Waxwings and tanagers, will happily consume fruit all year round.

In most cases, though, they won't digest the seeds -- they'll pass right through instead, possibly to germinate wherever they're deposited. This dispersal is quite important for the plants, (2) and appears to be the primary reason for the evolution of sugary or oily fruits in the first place. (All of that sugar or oil is energy the plant could be using for growth.) It also has important implications for conservation. First, fragmented habitats can reduce seed dispersal by birds and affect recruitment and gene flow in plant populations. (3) Second, many successful invasive plants are dispersed by birds. (4) In Lake County, that includes some particularly problematic species: 10 different species (including hybrids) of Honeysuckle (Lonicera sp.), and European Buckthorn (Rhamnus cathartica). (5)

Obviously, wiping out frugivorous birds to aid in eliminating Buckthorn would be throwing out the baby instead of the bathwater. Even if we didn't care about the birds, we'd be causing even more problems for a number of native plants. But it does throw an extra wrinkle into our conservation efforts when our native birds are part of the problem.

(1) Eiserer, L. A. (1980). Effects of grass length and mowing on foraging behavior of the American Robin (Turdus migratorius). The Auk, 576-580.

(2) Nathan, R., & Muller-Landau, H. C. (2000). Spatial patterns of seed dispersal, their determinants and consequences for recruitment. Trends in ecology & evolution, 15(7), 278-285.

(3) Levey, D. J., Bolker, B. M., Tewksbury, J. J., Sargent, S., & Haddad, N. M. (2005). Effects of landscape corridors on seed dispersal by birds. Science,309(5731), 146-148.

(4) Gosper, C. R., Stansbury, C. D., & Vivian‐Smith, G. (2005). Seed dispersal of fleshy‐fruited invasive plants by birds: contributing factors and management options. Diversity and Distributions, 11(6), 549-558.

(5) http://www.invasive.org/species/list.cfm?id=152

The Tyrant of March

An afternoon walk at Lyons Woods Forest Preserve produced one of these handsome little birds:

Eastern Phoebe (Sayornis phoebe), Illinois Beach State Park, 9/21/2012

This is an Eastern Phoebe (Sayornis phoebe), one of our Tyrant Flycatchers. They're a common breeding bird across most of the eastern US and a large swath of eastern and central Canada as well. They are also quite comfortable around people, routinely nesting under bridges, building eaves, etc. As a result, they've been an important research subject for biologists interested in the evolution of reproductive strategies.

An interesting aspect of phoebe biology is that they often reuse nests -- at least some nests. They are willing to place their nest either on top of a ledge (statant) or affixed to a vertical surface (adherent). Statant nests are sometimes reused, but adherent nests rarely survive the winter and are thus unavailable for reuse. (1) As you might expect, repairing and reusing a nest takes less time than building a new one, and that can be important for reproductive success in many birds -- starting too late can mean less food available for nestlings, and leaves less time available for either a replacement brood or (if lucky) a second brood.

Conrad & Robertson found that among nest builders, the type of nest built didn't affect clutch size or success rates, (1) while Hauber found that nest builders not only initiated their broods later but were less likely to succeed in nesting. (2) Conrad & Robertson also found that younger birds (SY, meaning second year) were less likely to succeed and raised smaller clutches when they did succeed than older birds (3) (ASY, meaning after second year -- aging these guys beyond that is impossible unless they were banded young). I don't know that anyone's examined the issue of the availability of old nests, or whether older birds are more likely to hold territories with old nests, but that does seem like a potential confounding factor here.

Hauber also found another effect of nest type: Brown-headed Cowbirds (Molothrus ater) were more likely to parasitize statant nests than adherent ones. He argued that this shows a preference by the cowbirds for safer nest sites (adherent nests failed more often, frequently from simply falling off!), but I'm not sure how he determined that the cowbirds' ability to detect the nests didn't vary. (4) He didn't find that nest building by the phoebes increased parasitism rates, although that would probably have biased the results the other direction, since adherent nests were never reused.

As a birder, the first Phoebe of the season is a wonderful moment -- it's a reminder of all of those migrants waiting just over the horizon for that first warm night of the season. After that, it's just another phoebe, while you try to find that Acadian or Yellow-bellied Flycatcher. Remembering that every species can be fascinating in it's own right, though, adds a deeper appreciation of the world around us.

(1) Conrad, K. F., & Robertson, R. J. (1993). Clutch size in Eastern Phoebes (Sayornis phoebe). I. The cost of nest building. Canadian journal of zoology,71(5), 1003-1007.

(2) Hauber, M. E. (2002). Is reduced clutch size a cost of parental care in Eastern Phoebes (Sayornis phoebe)?. Behavioral Ecology and Sociobiology, 51(6), 503-509.

(3) Conrad, K. F., & Robertson, R. J. (1993). Clutch size in eastern phoebes (Sayornis phoebe) II: age effects and seasonal variation. Canadian journal of zoology, 71(9), 1738-1742.

(4) Hauber, M. E. (2001). Site selection and repeatability in brown-headed cowbird (Molothrus ater) parasitism of eastern phoebe (Sayornis phoebe) nests.Canadian Journal of Zoology, 79(8), 1518-1523.

Chipmunks Galore!

Beautiful, if a bit chilly, today, and these guys are finally out:

Eastern Chipmunk (Tamias striatus),
Van Patten Woods FP, Lake Co, IL 10/20/2013

This is, of course, an Eastern Chipmunk (Tamias striatus). Here's another chipmunk:

Least Chipmunk (Tamias minimus), Devil's Tower National Monument,
Crook Co, WY  5/29/2013

This one is a Least Chipmunk (Tamias minimus). They don't live around here, but they are found across the northern edge of the US and south through the Rockies.

And there you have the entire cast of eastern chipmunks. The same can't be said for out west - although any one location may only have a couple of species, overall the US west of the Great Plains has 20 species! Many of them are very similar in appearance and have very limited ranges.

A similar pattern can be seen with tree squirrels -- 3 in the East, 6 in the West -- and Ground Squirrels, with 4 species on the Great Plains and 24 West of them. Mice (8 East, 19 West) and voles (7 East, 14 West) show the pattern as well. This suggests that western rodents tend to speciate much more readily than eastern ones. Why?

The obvious part of the answer is habitat -- not only is the West broken up by mountains, the areas between those mountains tend to be much less hospitable to strangers. Deserts are tough places for visitors to survive, and many of their regular residents don't do well away from them. So we get small populations in places they can't really leave.

We don't see the same pattern with larger animals. While there are 4 species of deer commonly found in the West and only 2 in the East, Elk (Cervus canadensis) used to range much more widely, and is being reintroduced to a handful of eastern states. With the possible exception of the Grizzly Bear (Ursus arctos), all of the west's large carnivores have historical ranges that include the eastern US. With rabbits, we see a much more equitable pattern -- 6 in the East and 8 in the West.

So, size could well be part of the explanation. Except for these guys:

Black-and-White Warbler (Mniotilta varia),
Waukegan Beach, Lake Co, IL 5/20/2012

This is a Black-and-White Warbler (Mniotilta varia). They're considerably smaller than most rodents, with the largest one weighing in at less than an ounce. And yet, we see 38 species in the East and only 19 in the West. What gives?

Well, part of the issue is that by flying, they utilize their habitat in more diverse ways -- one county in Maine could conceivably have 23 nesting species. But the other part of the story is that by flying, they can overcome the obstacles that rodents and other small mammals are faced with when trying to disperse across inhospitable habitat. Since isolation is typically an important part of speciation, populations of good dispersers tend not to speciate as frequently. This explains what we see in larger mammals as well, with deer and carnivores able to wander more widely, and thus to cross desert basins on a regular basis.

With all the focus on genes and development these days, it's easy sometimes to forget that evolution involves a species' response to the environment around them, and something as seemingly trivial as how far a critter can walk can have big implications for the future.

Bowers, Nora, Rick Bowers, & Kenn Kaufmann. 2004. Kaufman Field Guide to Mammals of North America. Houghton Mifflin Company, NY.

Sibley, David A. 2000. The Sibley Guide to Birds. Alfred A. Knopf, Inc. NY

Little Froggy Jewels

Spent yesterday at the Madison Zoo, so here's a couple of neat shots:

Golfodulcean Poison Frogs (Phyllobates vittatus),
 Henry Vilas Zoo, Madison, Dane Co, WI 3/22/2014

These are Golfodulcean Poison Frogs (Phyllobates vittatus), endemic to Costa Rica and considered endangered.

Strawberry Poison Frog (Oophaga pumilio),Henry Vilas Zoo, Madison, Dane Co, WI 3/22/2014

This is a Strawberry Poison Frog (Oophaga pumilio), found commonly across the southern half of Central America.

They are both in the family Dendrobatidae, often called poison-dart frogs. The poison in question is a combination of batrachotoxins, which are extremely toxic organic alkaloids. This, of course, explains how such a small, otherwise defenseless little frog can survive being bright orange.

Their toxicity has been known to science for over 200 years, ever since Dendrobates tinctorius was described in 1799. What hasn't been known for very long is that certain birds, called Pitohuis, carry the same batrachotoxins as the frogs! (1) That was first reported in 1992, when a graduate student from the University of Chicago noticed that his hands turned numb after handling the birds. In 2000, a new species of toxic birds, Ifrita, was discovered, again in New Guinea, again with batrachotoxins. (2) And since then, at least one author has argued that the genus is polyphyletic, including species from several different genera in the Corvoidea. (3)

The initial discovery of the birds seemed to indicate an amazing example of convergent evolution, with two entirely unrelated groups producing the same complicated toxin. But these later two discoveries make that just a bit too difficult to resolve. Some species of insects are known to sequester plant toxins in their own tissues, making them distasteful -- Monarchs (Danaus plexippus) and Pipevine Swallowtails (Battus philenor)  are both well known for this. So the same biologist who published the first paper went searching, and found a group of beetles that produce this toxin, the Melyrid beetles. (4) They are widespread, not only in the tropics, but in North America and Europe as well. So it's now thought that the convergence entailed the ability to sequester these toxins rather than succumbing to them. Similar convergences have been noticed in insects, with members of at least 3 orders (Lepidoptera, Homoptera, and Coleoptera) all able to do the same with toxic chemicals in Milkweed sap.

That one discovery of toxic birds in a New Guinea jungle has initiated an entire forest of research, into everything from phylogeny and physiology to the possibility of Mullerian mimicry in birds. All because a single grad student paid attention to the world around him, and took the time to think about not only what was happening to him, but why it might be.

And that is science at its best.

(1) Dumbacher, J. P., Beehler, B. M., Spande, T. F., Garraffo, H. M., & Daly, J. W. (1992). Homobatrachotoxin in the genus Pitohui: chemical defense in birds?.SCIENCE-NEW YORK THEN WASHINGTON-, 799-799.

(2) Dumbacher, J. P., Spande, T. F., & Daly, J. W. (2000). Batrachotoxin alkaloids from passerine birds: a second toxic bird genus (Ifrita kowaldi) from New Guinea. Proceedings of the National Academy of Sciences, 97(24), 12970-12975.

(3) Jønsson, K. A., Bowie, R. C., Norman, J. A., Christidis, L., & Fjeldså, J. (2008). Polyphyletic origin of toxic Pitohui birds suggests widespread occurrence of toxicity in corvoid birds. Biology letters, 4(1), 71-74.

(4) Dumbacher, J. P., Wako, A., Derrickson, S. R., Samuelson, A., Spande, T. F., & Daly, J. W. (2004). Melyrid beetles (Choresine): A putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds.Proceedings of the National Academy of Sciences of the United States of America, 101(45), 15857-15860.

Dwindling Wild Goats

I managed to spend an hour or so at the Racine Zoo today, so:

West Caucasian Tur (Capra caucasica), Racine Zoo, Racine Co, WI 3/21/2014

This is a West Caucasian Tur (Capra caucasica) -- a species I had never photographed before, which is always neat. It's considered to be endemic to the western Caucasus Mountains of Georgia and Russia, an area that boasts of 5 species of sheep and goats, more than any other on Earth.

They're listed as Endangered, with a 50% decline in population over the last 3 decades, largely due to excess hunting pressures. (1) (Some authors consider this to be the same species as the East Caucasian Tur (C. cylindricornis), which is only considered Near Threatened.) (2)

Humans (and their cousins) have been hunting these guys for a long time -- Mousterian archaeological sites frequently include Tur remains. (These would have been Neandertals.) But back then, we were doing so not only in the Caucasus region, (3, 4) but throughout Western Europe. (5,6, 7) This does make me wonder about the word endemic -- apparently as it's used here, it refers strictly to a species range during historic times. So there's two ways to become an endemic: evolve in one spot and remain there (Hawaiian Honeycreepers, for example), or experience a severe population drop and range restriction before anyone's bothering to pay attention.

The Mousterian falls during the last glacial period, so the environment around them has obviously changed, and it's probably impossible to determine how much human hunting had to do with their current absence from most of Europe. We do know that whenever modern humans have reached new areas, large animals have disappeared. This usually happened so long ago that the reasons are consistently controversial, though, and it's possible that we've repeatedly been innocent bystanders. But the recent declines are clearly the result of human activity, an all too common refrain, and one that grows more difficult to change as each year goes by.

I can't ask the Turs themselves, obviously, but it does look like this guy has his own opinions on the topic:

West Caucasian Tur (Capra caucasica), Racine Zoo, Racine Co, WI 3/21/2014

(1) Weinberg, P. 2008. Capra caucasica. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 22 March 2014.

(2) Weinberg, P. 2008. Capra cylindricornis. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 22 March 2014.

(3) Bar‐Oz, G., Belfer‐Cohen, A., Meshveliani, T., Djakeli, N., & Bar‐Yosef, O. (2008). Taphonomy and zooarchaeology of the Upper Palaeolithic cave of Dzudzuana, Republic of Georgia. International Journal of Osteoarchaeology,18(2), 131-151.

(4) Hidjrati, N. I., Kimball, L. R., & Koetje, T. (2003). Middle and Late Pleistocene investigations of Myshtulagty Lagat (Weasel Cave) North Ossetia, Russia.Antiquity, 77(298), 1-5.

(5) Rivals, F., Schulz, E., & Kaiser, T. M. (2009). Late and middle Pleistocene ungulates dietary diversity in Western Europe indicate variations of Neanderthal paleoenvironments through time and space. Quaternary Science Reviews,28(27), 3388-3400.

(6) Rivals, F., & Deniaux, B. (2005). Investigation of human hunting seasonality through dental microwear analysis of two Caprinae in late Pleistocene localities in Southern France. Journal of archaeological science, 32(11), 1603-1612.

(7) Valensi, P., Crégut-Bonnoure, E., & Defleur, A. (2012). Archaeozoological data from the Mousterian level from Moula-Guercy (Ardèche, France) bearing cannibalised Neanderthal remains. Quaternary International, 252, 48-55.

Even the Plants Know It's Spring!

Here's a March sight that I always look forward to:

Willow (Salix sp) catkins, Sedge Meadow FP,
Lake Co, IL  3/20/2014

Willow (Salix sp) catkins, Sedge Meadow FP,
Lake Co, IL  3/20/2014

These are willow catkins, just emerging from their buds. Soon, with a little warmth, they'll open up, and then the leaves will follow. This is usually one of the first plants to show that spring is here.

I'm not really sure which willow this is -- there are 400 species in the genus, although most of them don't occur around here. But ID'ing them to species is often quite difficult, regardless, since for many species you need both sexes of flower to key them out. And they're dioecious. That word is Greek for two houses -- in other words, there are separate male and female plants (so it can be rather difficult to say your two samples are from the same species!). If you're thinking that sounds normal, you're not a botanist. In most plants, both male and female structures appear on the same plant, in many cases in the same flower.

Why some plants have evolved a dioecious habit is still unclear. One explanation, to avoid self-fertilization and thus inbreeding, was discounted as early as the late 19th century -- Charles Darwin argued in favor of the idea in 1876, then reconsidered and argued against it in 1877 (1) , rather convincingly. Another explanation, niche partitioning to avoid intersexual competition, appears to have more going for it. (2) A particularly interesting example involves Arctic Willows (Salix arctica), where willows growing in wet areas are mostly females and those growing in dry areas are mostly male. (3) Dawson & Bliss showed that males transpire less water, and are more adaptable to varying water availability, and argue (but don't show) that this is due to differences in reproductive investments.

The marshes at Sedge Meadow Forest Preserve were noisy with Red-winged Blackbirds, Northern Cardinals, and American Robins today. In some respects, spring in the Midwest shouts its arrival with joy. By mid-April, the plants will be doing so. But for now, they whisper of warmth to come, and you have to listen, and look, close to see it.

(1) Darwin, C. (1877). The different forms of flowers on plants of the same species. John Murray, Albemarle Street.

(2) Cox, P. A. (1981). Niche partitioning between sexes of dioecious plants.American Naturalist, 295-307.

(3) Dawson, T. E., & Bliss, L. C. (1989). Patterns of water use and the tissue water relations in the dioecious shrub, Salix arctica: the physiological basis for habitat partitioning between the sexes. Oecologia, 79(3), 332-343.

Downtown Living

So what do these three species have in common?

Ferruginous Hawk (Buteo regalis)
Pueblo Co, CO 12/31/2005

Burrowing Owl (Athene cunicularia),
Henry Doorley Zoo, Omaha, NE  12/30/2011

Black-footed Ferret (Mustela nigripes)
Cheyenne Mt. Zoo, Colorado Springs, CO
12/27/2013

These are, from top to bottom, a Ferruginous Hawk (Buteo regalis), a Burrowing Owl (Athene cunicularia), and a Black-footed Ferret (Mustela nigripes). And what they share is an interest in these guys:

Black-tailed Prairie Dog (Cynomys ludovicianus) town,
Big Johnson Reservoir, El Paso Co, CO 12/24/2005

These are our old friends, Black-tailed Prairie Dogs (Cynomys ludovicianus), hanging out in a town in El Paso Co, Colorado.

All three species at the top of the post are associated with Prairie Dog towns in some respect. Ferruginous Hawks will happily prey on them, although they are quite willing to change diets when the opportunity arises. (1) Burrowing Owls rarely if ever eat Prairie Dogs, (2) but they do routinely appropriate unused Prairie Dog burrows, and on the Great Plains they are usually found on Prairie Dog towns. (3) Finally, Black-footed Ferrets are only found on Prairie Dog towns, using the burrows and happily dining on the occupants. (4)

Prairie Dogs have declined across their entire range (all 5 species, actually). While both the owls and the hawks can survive without Prairie Dogs, they usually do better on towns, and the Ferret would disappear completely without them. (Actually, in the 1970's, we thought that they had -- they were declared extinct in 1979, and rediscovered near Meteetsee, Wyoming in 1981.) Even if the Prairie Dogs don't disappear completely, if they become limited to small, isolated populations, those species that depend upon them may not be able to survive. Prairie Dog populations exist at a much higher density than any of the three predators shown above, so an area that's big enough for Prairie Dogs may not be for Ferruginous Hawks, for example. This is a case where a species that may not qualify for the Endangered Species List (Prairie Dogs) may nonetheless require a similar level of protection, simply to protect other species.

The Endangered Species Act has preserved quite a few fascinating critters -- but it was passed in 1973, and we've actually learned a few things about both ecology and conservation since then. Given the curious legal status of the act, it's probably worth considering how it could best be updated to account for our improving understanding of the natural world.

(1) Cartron, J. L. E., Polechla Jr, P. J., & Cook, R. R. (2004). Prey of nesting ferruginous hawks in New Mexico. The Southwestern Naturalist, 49(2), 270-276.

(2) York, M. M., Rosenberg, D. K., & Sturm, K. K. (2002). Diet and food-niche breadth of Burrowing Owls (Athene cunicularia) in the Imperial Valley, California.Western North American Naturalist, 62(3), 280-287.

(3) Tipton, H. C., Doherty Jr, P. F., & Dreitz, V. J. (2009). Abundance and density of mountain plover (Charadrius montanus) and burrowing owl (Athene cunicularia) in eastern Colorado. The Auk, 126(3), 493-499.

(4) Miller, B., Biggins, D., Hanebury, L., & Vargas, A. (1994). Reintroduction of the black-footed ferret (Mustela nigripes). In Creative conservation (pp. 455-464). Springer Netherlands.

Feathered Foster Kids

Found my first Brown-headed Cowbird (Molothrus ater) of the year today. Looked just like this one that I photographed last year:

Brown-headed Cowbird (Molothrus ater),
Illinois Beach SP, Lake Co, IL  5/20/2012

This is a male; females are a drab brown color. Last September, today's bird might have looked like this:

Brown-headed Cowbird (Molothrus ater),
Illinois Beach SP, Lake Co, IL  9/20/2011

This is, of course, a young male molting out of juvenile plumage into his first adult feathers.

And before that, he may have looked like this:

Common Yellowthroat nest, Spring Bluff FP, Lake Co, IL 5/16/2012

This isn't a cowbird nest, although the majority of the eggs are from cowbirds. The owners of this nest are a pair of luckless Common Yellowthroats (Geothlypis trichas):

Common Yellowthroat (Geothlypis trichas),
Gander Mt. FP, Lake Co, IL 7/31/2012

What are cowbird eggs doing in a warbler nest? The answer to that is the reason why so many birders have issues with cowbirds. They are what's known in the trade as brood parasites. They lay their eggs in someone else's nest, and let those birds raise the young cowbirds. Baby cowbirds are larger than most of their adopted siblings, faster to develop, and noisier, all of which means that they get the majority of the food that the parents deliver. Some parents will even work themselves to death trying to support the changelings. Relatively few of the host parents successfully raise their own young when they've got cowbird babies to handle.

Brown-headed Cowbirds are native to the Great Plains, and many of the species around here have developed techniques for dealing with the threat. Yellow Warblers in the Midwest, for example, will actually build a second nest on top of the one with the eggs, sacrificing their own eggs for a chance at a brood they can successfully raise. But Brown-headed Cowbirds do very well in human dominated landscapes, and have expanded their range dramatically. Many species that haven't had to deal with brood parasites don't have those defenses, and in some cases the Cowbirds have seriously impacted populations. Least Bell's Vireo (Vireo bellii pusillus) in California and Kirtland's Warbler (Setophaga kirtlandii) in Michigan are examples of species that are actually managed, in part, by aggressive action to reduce Cowbird numbers in their known breeding locations.

The impacts of cowbird parasitism appear to vary both by habitat fragmentation and location: Hoover, et. al. found that forest patch size didn't impact parasitism rates in Wood Thrushes (Hylocichla mustelina) in Pennsylvania (although it did impact predation on nests), (1) while Trine found that it did have impacts in Illinois. (2) She also found that patches in Illinois were population sinks for thrushes at sizes that are consistently population sources in Pennsylvania. In the West, where cowbirds are relatively recent immigrants, Airola found that parasitism rates increased with human disturbance, at least in parts of the Sierra Nevada. (3)

Cowbirds aren't really an invasive species - they haven't been moved into those new areas. Instead, they've moved in on their own as we've altered place after place to suit our own needs. Unfortunately, that's the sort of change that has ramifications beyond anything we intended at the time.


(1) Hoover, J. P., Brittingham, M. C., & Goodrich, L. J. (1995). Effects of forest patch size on nesting success of Wood Thrushes. Auk, 112(1), 146-155.

(2) Trine, C. L. (1998). Wood thrush population sinks and implications for the scale of regional conservation strategies. Conservation Biology, 12(3), 576-585.

(3) Airola, D. A. (1986). Brown-headed Cowbird parasitism and habitat disturbance in the Sierra Nevada. The Journal of wildlife management, 571-575.

Dangerous Little Treasures

Here's a sinister looking critter:

Eastern Massassauga (Sistrurus catenatus),
St. Louis Zoo, St. Louis, MO 3/2/2012

This is an Eastern Massassauga, (Sistrurus catenatus), a small rattlesnake which used to be the only venomous snake found in Lake County. I say used to because in 2009, biologists collected the last few known in the county for a breeding program at the Lincoln Park Zoo in Chicago. Even when they were here, though, they were hard to spot.

Although the species as a whole is listed as of Least Concern by the IUCN (1) , it is listed as endangered in Illinois (2) , as it is in most states, and it's a candidate species for Federal listing as well. (3)

This isn't the only viper to be considered endangered. Out of 182 viper species, the IUCN lists 24 as Endangered or Critically Endangered, with 12 more listed as Data Deficient, meaning we don't know enough to say. (1) Here's one of the Endangered ones:

Ocellate Mountain Viper (Vipera wagneri),
St. Louis Zoo, St. Louis, MO 3/2/2012

This is an Ocellate Mountain Viper (Vipera wagneri) from Turkey and Iran. Ironically, it's threatened in part by collectors looking for rare species to display.

Focusing only on species also doesn't capture the entire picture: this next snake is considered part of a common species, but the subspecies it belongs to is Critically Endangered, with perhaps 200 left in the wild.

Aruba Island Rattlesnake (Crotalus durissus unicolor),
Louisville Zoo, Jefferson Co, KY 3/28/2013

This is an Aruban Island Rattlesnake (Crotalus durissus unicolor), found only on the island of Aruba.

All of these are venomous, of course, and all are potentially dangerous. Most snakebites, even from venomous snakes, aren't fatal to healthy adult humans, but that doesn't mean you'd enjoy the process. And yet, we humans are doing just fine, even in places with plenty of venomous snakes, while the snakes themselves seem to be having their problems. It looks as if we're the truly dangerous animals!

It's easy to think of dangerous animals as something we need to get rid of to be safe. But the world isn't safe, and trying to make it so far too often produces results we don't particularly care for. I've hiked in Grizzly country, and I've encountered wild rattlesnakes on a number of occasions. Knowing they're not out there does make walking our woods here in Lake County a more relaxing experience, I suppose, but it does mean you don't have to be quite so alert, and is that really what we want when we're out in the wild?

(1) IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 18 March 2014.

(2) http://www.dnr.illinois.gov/ESPB/Documents/ETChecklist2011.pdf

(3) http://www.fws.gov/midwest/endangered/reptiles/eama/eama_qanda.html

A Northern Family Reunion

According to the weathermen, winter's not quite over, and today they seemed intent on proving it. So here's a bird that's named after a place where winter holds sway:

Lapland Longspur (Calcarius lapponicus),
Wind Point, Racine Co, WI 9/25/2013

This is a female Lapland Longspur (Calcarius lapponicus). They nest on tundra in Canada, Alaska, and Eurasia.

She looks rather like our sparrows and even more like the Eurasian Emberiza buntings, and for a long time they were included in the family Emberizidae with them. It was thought at the time that the family got started in North America and expanded west into Eurasia fairly recently.

Work in the 1990's pretty much wiped that concept out. Calcarius is now recognized, along with the Snow Buntings (Plectrophenax) and the McCown's Longspur (Rhynchophanes mccownii), to make up the family Calcariidae. (1) The supposed recent expansion of the family into Eurasia also fell by the wayside: genetic disparities appear to be similar in both Emberizid groups, indicating that they began their current radiations at about the same time. (1,2)

The family Calcariidae is mostly North American, with only the Snow Bunting (P. nivalis) and Lapland Longspur occurring in Eurasia. Here's a female Chestnut-collared Longspur (C. ornatus):

Chestnut-collared Longspur (Calcarius ornatus), Kidder Co, ND  6/2/2013

And since the females are so drab, here's a male Chestnut-collared:

Chestnut-collared Longspur (Calcarius ornatus), Kidder Co, ND  6/2/2013

More recent work by Klicka, et al. clarified relationships within the family itself. (3) Plectrophenax and Rhynchophanes turn out to be sister genera (which explains why mccownii is no longer in Calcarius), and C. ornatus is the sister species to Smith's Longspur (C. pictus), with Lapland as a sister species to that pair. This seems like trivia, but it points out a very interesting pattern: the two southern species (mccownii and ornatus) are not, as might be expected, each other's closest relatives. Instead, each half of the family sent a representative south to colonize the Great Plains. That sort of event is something that we couldn't have deduced without the fine-scale systematics work discussed here. Without that sort of detail, our views of the evolutionary history of our Earth will never be more than broad brush strokes, which is why this sort of work is so interesting to see.

(1) Grapputo, A., Pilastro, A., Baker, A. J., & Marin, G. (2001). Molecular evidence for phylogenetic relationships among buntings and American sparrows (Emberizidae). Journal of Avian Biology, 32(2), 95-101.

(2) Watada, M., Jitsukata, K., & Kakizawa, R. (1995). Genetic divergence and evolutionary relationships of the Old and New World Emberizidae. Zoological science, 12(1), 71-77.

(3) Klicka, J., Zink, R. M., & Winker, K. (2003). Longspurs and snow buntings: phylogeny and biogeography of a high-latitude clade (< i> Calcarius</i>).Molecular phylogenetics and evolution, 26(2), 165-175.