A Proper Mink Coat

This little guy seemed remarkably unconcerned about my presence this afternoon:

This is an American Mink (Neovison vison), a rather large member of the weasel family. He was hunting the rocks along the side of N. Pt. Marina, hoping to find some mice for dinner.

This is the same species that mink coats are made of, and these days they are intensively farmed for their fur. Here in the US and in Canada, this is a cause for concern, since domesticated mink are genetically distinct from wild ones by now. When they escape, some are able to survive, and can dilute the gene pools of wild mink in the area. (1)

In Europe, this is even more of a concern -- in addition to farm escapes, wild mink have been released in a number of countries as a source of fur. As they are semiaquatic predators, it isn't surprising that they've been implicated in declines of muskrats, at least in Poland. (2) (Muskrats are a favored food in their native range as well.) These days, mink control programs are common throughout Europe, (3)  but they are hampered by continuing escapes of domesticated mink. (4)

There does appear to be some hope in this regard, though. Some island populations have actually been eradicated, in part through careful consideration of how the mink respond to trapping pressure. (5) Modelling efforts suggest that eradication may even be possible in some mainland populations. (3)

Of course, my little model is a native mink, and there's no pressure at all to get rid of him. Which means he's still free to consider me a curiosity:

(1) Kidd, A. G., Bowman, J., Lesbarreres, D., & SCHULTE‐HOSTEDDE, A. I. (2009). Hybridization between escaped domestic and wild American mink (Neovison vison). Molecular Ecology, 18(6), 1175-1186.

 

(2) Brzeziński, M., Romanowski, J., Żmihorski, M., & Karpowicz, K. (2010). Muskrat (Ondatra zibethicus) decline after the expansion of American mink (Neovison vison) in Poland. European journal of wildlife research, 56(3), 341-348.

 

(3) Zabala, J., Zuberogoitia, I., & González-Oreja, J. A. (2010). Estimating costs and outcomes of invasive American mink (Neovison vison) management in continental areas: a framework for evidence based control and eradication. Biological invasions, 12(9), 2999-3012.

 

(4) Zalewski, A., Michalska-Parda, A., Bartoszewicz, M., Kozakiewicz, M., & Brzeziński, M. (2010). Multiple introductions determine the genetic structure of an invasive species population: American mink< i> Neovison vison</i> in Poland. Biological Conservation, 143(6), 1355-1363.

 

(5) Bodey, T. W., Bearhop, S., Roy, S. S., Newton, J., & McDonald, R. A. (2010). Behavioural responses of invasive American mink Neovison vison to an eradication campaign, revealed by stable isotope analysis. Journal of applied ecology, 47(1), 114-120.

 

(6) Zalewski, A., Michalska‐Parda, A., Ratkiewicz, M., Kozakiewicz, M., Bartoszewicz, M., & Brzeziński, M. (2011). High mitochondrial DNA diversity of an introduced alien carnivore: comparison of feral and ranch American mink Neovison vison in Poland. Diversity and Distributions, 17(4), 757-768.

 

 

Aquatic Beauties

 Here's a little beauty:

This is a Fragrant Water Lily, Nymphaea odorata. It's one of  approximately 36 species in the genus, itself one of 7 or 8 genera in the family Nymphaeaceae. According to the Flora of North America website, this is one of 9 species of Nymphaea that occur in North America.

The entire family is often referred to as water-lilies, of course, since they are entirely aquatic. They grow rooted to the bottom of ponds and slow rivers, with leaves submerged, emergent, or floating on the surface. The flowers are raised above the surface to some degree, as seen here:

In addition to their beauty, and their ecological importance in warm wetland areas, water lilies are of interest to botanists because of their taxonomic position. They are generally thought of as the second most basal group of angiosperms, branching off from the other flowering plants just after Amborella did so. A recent paper, however, argues that Amborella is the sister group of a Nymphaeaceae - Hydatellaceae clade. (Hydatellaceae is a small family of minute aquatic plants.) This means that the water lilies are direct descendants of that first branch off the flowering plants, basal to all of the other angiosperms.

Water lilies and Hydatellaceae are aquatic plants, but Amborella is a land plant, as are most of the angiosperms. So: were the original angiosperms aquatic, with Amborella climbing onto land, or were they terrestrial, with the water lilies aquatic preference evolving after that next split?

In a similar vein, Amborella has vascular tissue that is missing certain elements normally found in angiosperms (one reason why they've been considered a basal group). But if they're in a clade with two or three other families that do have that tissue, did they somehow lose those elements? Or is this an interesting case of convergent evolution between the Nymphaeaceae and the rest of the angiosperms?

The Evolutionary Root of Flowering Plants. Vadim V. Goremykin, Svetlana V. Nikiforova, Patrick J. Biggs, Bojian Zhong, Peter Delange, William Martin, Stefan Woetzel, Robin A. Atherton, Patricia A. Mclenachan, and Peter J. Lockhart. Syst Biol (2013) 62 (1): 50-61 first published online July 31, 2012 doi:10.1093/sysbio/sys070

Salt-water Musicians?

Here's a critter from deep in the archives (if not so deep in the sea).

This is a Brown Guitarfish (Rhinobatos schlegelii), from the Denver Aquarium. While he looks like a cross between a stingray and a shark, he's actually considered to be in the family Rhinobatidae, in the Order Rajiformes. (That is, he's a ray, but closer to the skates than the stingrays.) He's found in the western Pacific, from Korea to Australia. 1 There are 50 species of these guys, found throughout the warmer oceans of the world. 2  Mostly they hang out in shallow coastal waters, eating snails, clams, and other bottom-dwellers.

I haven't had much luck finding studies that focused on this one, although Fishbase does state that it's a fine eating species, but other species, such as the Common Guitarfish (R. rhinobatos) from the Eastern Atlantic and Mediterannean, and the Shovelnose Guitarfish (R. productus) from the west coast of the US and Mexico, are quite well-studied, from distributions to reproductive biology 3,4,5,6 to genetic variation. 7

That last study found something quite interesting to my mind -- unrecognized genetic differentiation between fish from the west coast of Baja California and those from the Gulf of California just to the east. The authors didn't go so far as to claim the two forms were separate species, but they did point out that this sort of variation should be a concern when we're contemplating conservation or management measures. This species isn't endangered, but several others are, including the Common Guitarfish. (Brown and Shovelnose are listed as data-deficient by the IUCN).8

While the Brown and Shovelnose aren't considered endangered, they are both heavily fished, so all of this study, including the ongoing taxonomic work, are very important, if we want to keep them around.


1) http://www.fishbase.org/summary/Rhinobatos-schlegelii.html

2) http://en.wikipedia.org/wiki/Guitarfish

3) Enajjar, S., Bradai, M. N., & Bouain, A. (2008). New data on the reproductive biology of the common guitarfish of the Gulf of Gabes (southern Tunisia, central Mediterranean). Journal of the Marine Biological Association of the UK, 88(05), 1063-1068.

4) Ismen, A., Yıgın, C., & Ismen, P. (2007). Age, growth, reproductive biology and feed of the common guitarfish (< i> Rhinobatos rhinobatos</i> Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea. Fisheries Research, 84(2), 263-269.

 

5) Abdel-Aziz, S. H., Khalil, A. N., & Abdel-Maguid, S. A. (1993). Reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Alexandria waters, Mediterranean Sea. Marine and Freshwater Research, 44(3), 507-517.

 

6) Sandoval-Castillo, J., Rocha-Olivares, A., Villavicencio-Garayzar, C., & Balart, E. (2004). Cryptic isolation of Gulf of California shovelnose guitarfish evidenced by mitochondrial DNA. Marine Biology, 145(5), 983-988.

 

7) Márquez-Farías, J. F. (2007). Reproductive biology of shovelnose guitarfish Rhinobatos productus from the eastern Gulf of California México. Marine biology, 151(4), 1445-1454.

8) The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 16 October 2014.

(Nearly) Lost Wanderers

Early October, and soon we'll be seeing the last of these guys winging their way past the watch:

This is a Peregrine Falcon (Falco peregrinus). The name literally means wanderer, and it's appropriate. They live on every continent except Antarctica, and routinely show up in Hawaii.

There was a time, however, when this would have been an exceptional sight here in Illinois:

Starting after World War II, the US started using DDT to control mosquitoes and other insects. We used a lot of it, much of it for agricultural purposes. We didn't realize, though, that it bioaccumulates, (in other words, the higher trophic level you feed on, the more you absorb) especially in aquatic systems. Neither did we recognize that in larger doses it has serious impacts on calcium metabolism in birds.

Peregrines feed largely on ducks and shorebirds. (Well, today a lot of them feed on pigeons, but that's a rather new development.) That puts them squarely in a high trophic level, at the top of an aquatic system. So it's no surprise that they got doses more than high enough to disrupt calcium uptake. This is especially important for birds, since their eggshells are primarily made up of calcium. In the case of Peregrines, in the eastern US, eggs became so fragile that the females couldn't successfully incubate them. And by the early 1970's, Peregrines were no longer found east of the Mississippi.

After DDT was banned in the US in 1972, several of the most heavily impacted birds began to rebound. (Osprey, Bald Eagles, Brown Pelicans). But there weren't any Peregrines left to start a recovery. Into this gap stepped the folks at the Peregrine Fund. They raised a bunch of money, began to acquire Peregrines from elsewhere, and then learned how to successfully reintroduce them. As a result, they were removed from the US Endangered Species List in 1999.

But where did they come from? Therein lies an interesting debate on the nature of subspecies and the authenticity of our natural history.

The eastern anatum was gone -- there were a few pairs breeding in easternmost Canada that appeared to have been anatum, and that was it. Out west, they were still hanging on in scattered locations. So, what to do? Try to catch a few of the Canadian birds (which might have unfortunate effects on the one wild population left), or bring some western birds east?

Or you could try what the Peregrine Fund actually did -- bring in birds from all over the world, and rely on natural selection to sort out a new subspecies that would be well-suited to this new environment. (And a new environment it is -- many of the original nesting areas have become unsuitable, whereas many of today's birds nest in high-rise buildings in various cities.) These new birds are currently termed "mutts" by many raptor enthusiasts. I've been told that "nothing about Peregrine's nesting in Chicago is natural", to which I reply "What about Chicago IS natural?"

Admittedly, this is a long-term strategy. It will be decades, probably even centuries, before we can expect a population that is homogeneous enough to give it a subspecies designation all its own. But then again, that's how natural selection works.
One of the things that interests me about this is the insistence that the Canadian birds were still anatum, so they should have been used. Yes, they looked like birds from New York or Illinois, (or Florida, even), but does that mean that they would be genetically well-adapted to this area? That's an open question -- for most species, we don't have any idea how closely the genetics follow appearances across populations, and even if we did, we don't know which genes are important in adapting to local conditions. (Or even how closely those genes correlate with environmental variation.)

I do find the debate interesting, but fortunately for my own peace of mind, I find myself in agreement with the Peregrine Fund. This is a neat long-term experiment in applied evolutionary biology, and if we're still willing to do the work in the decades to come it could prove invaluable in helping us learn how species can adapt to the changes we like to make in our environment.

No matter how you feel about the current situation, though, it's neat to know that this shot could be across the sunrise of a new population, and not the sunset of a species:

Turf Birds

Here's a find from a few days ago:

This is an American Golden Plover (Pluvialis dominica). He's migrating through, on his way from the tundra of northern Canada to the pampas of Argentina. As a plover, he would be considered a shorebird, and we did in fact find him on a shore (a lakeshore, but...):

This was at Illinois Beach State Park, here in Lake County. Around here, these birds aren't easy to find. Most of the large plovers that move down the lake turn out to be these guys:

These are Black-bellied Plovers (Pluvialis squatarola). They breed in the same Arctic tundra, but many of them spend the winter along the Gulf and Atlantic Coasts instead.

As I said, Golden Plovers are hard to find here in Lake County. But elsewhere in Illinois... A significant portion of the world's population of this species migrates through central Illinois, where a good day scouring sod farms (with a scope, preferably) can yield several hundred of them. Sod farms, of course, can hardly be considered shorelines, but some "shorebirds" actually prefer them. Here's another example:

This is a Buff-breasted Sandpiper (Calidris subruficollis), another sod farm specialist, and another species more easily found in the Midwest than just about anywhere else.

This preference made sense, when this area was full of prairies, prairie fires, and bison. Now that the bison are gone, most of our prairies are tiny little patches, and prairie fires are carefully managed, they seem to be dependent upon our desire for short, green grass. But sod farms are, after all, businesses, and they have no choice but to respond to the economic environment. These days, many of our local sod farms have been slowly converting to corn, as demand for sod goes down. What this means for Golden Plovers and Buff-breasted Sandpipers, we don't really know. But it does illustrate an intriguing way in which economics can impact the natural world we live in.

A Melodrama For Three Parts

Here's a beautiful little critter that came by our hawkwatch yesterday:

This is a Merlin (Falco columbarius), another small falcon. Whereas Kestrels are all about elegance and grace, Merlin are all about power and speed. We sometimes say that Merlin shouldn't be a two-syllable word, because you don't have the time to say it!

Here's one dining on the wing -- they do this a lot as they migrate south.

What's he eating? Probably a close relative of this guy:

This is a Canada Darner (Aeshna canadensis) that also showed up on the hill yesterday. We don't see many of them, but we do see a lot of Common Green Darners, in the same family. (Although in a different genus -- they're formally known as Anax junius.) They appear to be a favorite snack for migrating Merlin.

Darners are also voracious predators of smaller insects, with darners specializing in flying prey.

This particular guy, though, fell afoul of yet another predator:

This beauty is a Banded Argiope (Argiope trifasciatus). She's a big spider, with a body close to an inch in length, and she's going to need every bit of her size and venom:

You may have heard people talk about the food chain. Some might even understand the concept. But the food chain is a wonderful example of what Jack Cohen and Ian Stewart call Lies to Children. (aka education) Nature is so much more complex than a simple chain -- here we have a notable predator (the darner) being eaten by two other predators (the Merlin and the spider), with nary a producer (i.e. plant) in sight -- any plant is at least two steps back in the system, and possibly more. If we had followed this darner through his entire life, we might well have found him eating a baby Argiope trying to reach a new home. Or we might have seen him eating a mosquito that had just fed on a female Merlin returning to her nest with another dragonfly for her hungry chicks.

Lies to Children refers to simplified stories that we tell children (or college students, etc.) so that later on, they're ready to understand the more complicated truth. Except that science is, in the end, about telling each other stories about how the world works, and since the world is bigger and more complex than our poor brains, we have to tell each other lies as well. We can, of course, hope to find more accurate lies, and who knows, maybe sometimes we do hit the real truth. After all, we really do know more about how the world works than we ever used to. But without a teacher out there to tell us how we did, we can never really know we've got it right. We can figure out that we're less wrong than we once were, though, and that's a useful thing indeed.

Making Sense of Hawks

We started our hawkwatch Saturday, and we've had a few things to look at so far. (The first couple of weeks are always rather slow -- if you want to be sure that you're catching the entire migration, you've got to put up with some slow days.)

This beauty came by last Sunday:

He's an immature Red-tailed Hawk (Buteo jamaicensis). He didn't appear to be migrating, though, which isn't surprising. We know they nest in the park where we count.
On Monday, this lovely lady took a look at our site:

This is a female American Kestrel (Falco sparverius). She had caught something, possibly a grasshopper, and we watched her eat on the wing as she went by.

The Kestrel is, as the Latin name suggests, a falcon, in the family Falconidae and the order Falconiformes. She's got a strongly hooked, sharply pointed bill, strong feet with large pointed claws, and long, sharply pointed wings to enable her to fly very fast and maneuver very efficiently. The hawk is in the family Accipitridae (Accipiter simply means hawk in Latin). While the wings aren't sharply pointed, the bill and feet are very similar, and the wings are still long enough to allow for impressive flying abilities. Both families also specialize in eating not only other animals, but frequently other chordates. It's probably not a surprise that traditionally, then, the Accipitridae has been included in the Falconiformes.

What may be a surprise, though, is that they are no longer placed there. In fact, Accipitridae is now in the order Accipitriformes (formed when they were removed from Falconiformes). What's probably more of a surprise is that the Accipitriformes are now considered to be the sister group to a clade of owls, trogons, hornbills, kingfishers, and woodpeckers, while the Falconiformes are seen as the sister group of a clade composed of songbirds and parrots.

And what should we make of this guy:

This is a Turkey Vulture (Cathartes aura), in the family Cathartidae. The family is strictly New World, with 7 species, 3 of which are found in North America. (There are a few finds that suggest they were more widespread in the Pleistocene.) He has a nicely hooked bill, but the feet aren't nearly as strong, and while he's also a chordate eater, he very rarely kills for a meal. Vultures are patient critters that wait for animals to die on their own before they dine.

Historically, they have been placed in the Falconiformes. Before that order was split, though, the Cathartidae were moved into the Ciconiiformes, with a number of authors arguing that they were actually similar to storks. (This discussion only applies to the Cathartidae -- Old World vultures have always, to my knowledge, been included in the Accipitridae.) Some authors subsequently have placed them in an order all their own, Cathartiformes, while others have actually argued for a label of incertae sedis (aka "we have no idea what these things really are!"). The same large-scale analysis that led to the Accipitriformes, though, supported placing the Cathartidae back with the hawks, and at the moment, the AOU checklist has them in Accipitriformes with the hawks, eagles, kites, and Secretary Bird.

Through it all, we've been faithfully counting all of them, and we'll of course continue to do so. Knowing about the evolutionary history is wonderful, but keeping them around is a pretty important goal as well, and we hope that keeping track of them is a small part of that. With luck, I'll never have to try to communicate the thrill that we used to get watching them sail past.

Oh, and just because, here's a King Vulture (Sarcoramphus papa) from the St. Louis Zoo: