On the swift’s scuttly wingless fly friend

May 28, 2015 • 3:52 pm

by Matthew Cobb

Earlier today I posted a video of a pair of swifts that met up for the first time in 9 months. In the comments, Mark Sturtevant pointed out that on the male (the front bird) you can see an ectoparasite scuttling about:

swift

Here’s the video again. Go to 50 seconds, which is about the first moment you can see the parasite, as a white blob on the back of the male’s neck. It starts scuttling around and can be clearly seen at around 1:10.

Chat on the comments and on Twitter identified the beast in question as probably Crataerina pallida, a wingless fly like the wingless bat louse fly Jerry posted the other day. Morgan Jackso (aka @bioinfocus) has gone on to pose some interesting questions about this particular fly over on his website Biodiversity in Focus.

You should head over there to see the full argument, but Morgan’s starting point is that this species does not lay eggs, but instead gives birth to live maggots, that presumably overwinter as pupae in nest boxes:

This leads us to an interesting question of how this louse fly got onto this bird! The fly was already aboard the bird when it entered the box (if you watch closely you can see a white blob that moves around neck is first visible at 0:06, immediately after the male bird approaches the sitting female). This means that one of two things happened: either the male bird has in fact carried its little parasite friend down to Africa and back (something that neither Hutson nor Walker & Rotherham (2010) believe to be the case) (and assuming this was the first nestbox that the bird stopped in, which I take to be the presumption of the ornithologists who posted the video and stated it shows a male reuniting with its mate from last year in last year’s nestbox), or alternatively, the male bird did stop for a time in another nestbox where it picked up its little hitchhiker, and then proceeded on to its longterm mate.

Curiouser and curiouser. Even more curiouser, as we were chatting about this on Tw*tter, the BBC programme Springwatch showed a video of their swift cam, showing a brooding female, who also had one of these beasts scuttling about on her. Lewis Spurgin, who ID’d the beast on our post, said:

https://twitter.com/LewisSpurgin/status/604009504343244800

If you have expert knowledge on this, please chip in below, and on Morgan’s site!

Cooperative hunting in groupers and moray eels

May 28, 2015 • 11:43 am

Here’s a short video from Nature that isn’t based on a single research paper, but on the continuing work of Redouan Bshary, a biologist in Switzerland who studies interspecific communication and behavior in fish.  The article itself, a summary of Bshary’s work written by Alison Abbott, is called “Animal behaviour: Inside the cunning, caring and greedy minds of fish“, and deals largely with the relationship between cleaner wrasses and their “cleanees.”

It turns out that this relationship is far more complex than the simple symbiotic relationship I’ve always taught (“cleaneee gets dead skin and parasites removed, cleaner gets a meal”). There is cheating by the cleaners, punishment by those fish who get a bum job of cleaning, and all kinds of complex social dynamics.

The video accompanying the article, however, deals with a different interspecies relationship—that between groupers and moray eels who seem to hunt “cooperatively”:

Now from the video alone, it looks as if the grouper is getting all the benefits, using the moray eel to flush prey for him (note that this also involves the moray leaving the safety of its den in the reefs). The experiments shown at the end demonstrate learning ability in groupers, but one question is missing in all this: What does the moray get out of it?  This behavior would not evolve (or persist, if it’s not genetically based) if both species didn’t derive some benefit from it. My immediate reaction would be that the moray gets some noms, too, but this isn’t mentioned in the video, which seems to show that all the benefits devolve to the grouper.  A better video would explain the benefits to both partners.

One alternative, which I find unpalatable and not biologically sound, is that the groupers are enslaving the morays as sort of a hunting d*g, to flush prey for them.  In this scenario the moray gets nothing. However, in nature we don’t see this kind of slavery very often, though it’s the norm for humans and their d*gs.

h/t: John

Swifts reunited

May 28, 2015 • 8:18 am

by Matthew Cobb

Spring is about to give way to summer in the northern hemisphere, and the swifts are back! My favourite bird, the swift (closely related to the nightjar, don’t you know) arrives in Europe at the beginning of May. They produce one clutch of eggs, and then return to Africa in the middle of August. They appear to mate for life, and to return to the same nest box. This charming and apparently unique video from a swift nest-cam shows the moment when a pair meet again, for the first time in nine months.

The video was recorded by staff at the charity BirdLife, who have had a swift nest box and cam installed on the side of their building in Cambridge. The video was recorded from the monitor rather than directly from the camera feed, so initially you can hear sounds from the office.

Although it looks like this is the moment the pair were reunited, we can’t be sure. The BirdLife website is rightly circumspect and says it “most-likely shows a pair re-affirming their bonds in preparation for nesting”. The reasons for this supposition are as follows:

According to local experts, the ‘wing flapping’ behaviour exibited in the video is a way of stopping aggression when the two meet again or when a bird attracts a new partner. However, courtship and encouraging a new prospective partner to use a nestbox are usually rather more drawn-out affairs than the behaviours displayed here, thus it is very likely that this is last year’s pair meeting up again and re-affirming their bond.

Whatever the case, the video gives a unique insight into how these birds interact. My assumption is that the recognition involves sounds and smells, (swifts have huge nostrils) but who knows?

Readers’ wildlife photographs

May 28, 2015 • 7:45 am

Today we have an odd combination: Galápagos iguanas and squirrels. First the iguanas, from reader Kris Rossing, who is too humble about these lovely photos.

I am a practicing biologist and longtime reader. I greatly enjoy your website and find the community of regular commentators extremely thoughtful and respectful. I particularly enjoy the user submitted photos. It is clear that some readers have exceptional skill, transforming the mundane into magic; the trivial into transcendent.
As such, I’ve been nervous about posting these, but as I have yet to see pictures from the Galapagos [JAC: we have more coming from another reader soon], I hope that these images will still be enjoyable to the avid biologists among your readers. I thought I’d start by submitting some photos of one of the Galapagos’ most iconic species.
Our trip was during the first two weeks of October, at the onset of the breeding season of the marine iguana (Amblyrhynchus cristatus). As the warm currents hit eastern-most San Cristobel first, the males on this island were beginning to don their full mating regalia, resplendent in green and red. This male eventually decided we were close enough and began his iconic head-bobbing dance, proclaiming his dominance of that particular rock for all to see.
Amblyrhynchus cristatus (Marine Iguana) 01
Further west, on Isabella, we encountered what the locals called a nursery; a huge and isolated tract of rocky shoreline occupied almost exclusively by the young. This photo was taken in the morning, as they bask to gain energy for the trials of the day ahead. As much as the lifestyle looks easy now, anyone familiar with their exclusive dietary habit is already cringing at the thought of plunging into the surprisingly cold waters below.
Amblyrhynchus cristatus (Marine Iguana) 02
After they gorge on algae, they haul themselves back on land to digest and warm up. We caught this fellow (first photo) on his way to a power-nap party among the mangroves (second photo).
Amblyrhynchus cristatus (Marine Iguana) 03
Amblyrhynchus cristatus (Marine Iguana) 04
Later in the evening we encountered this beast of a male. His mating colours are only just barely beginning to show, but he was easily the largest iguana we saw on our trip. He didn’t even flinch as I approached for the money shot (second photo). I can’t help but feel that the orc race of many fantasy worlds must have been modeled on this amazing animal. His salt-encrusted scales are simply striking.
Amblyrhynchus cristatus (Marine Iguana) 06
Amblyrhynchus cristatus (Marine Iguana) 05
To any readers who have ever considered going, I say “Do it!”. There will be precious few experiences in life that can top sharing a sunset on the beach with a marine iguana sitting on a log only a few inches away.
JAC: I fully agree with Kris. When I went to the Galápagos (as a lecturer on a wonderful Lindblad cruise), I thought I knew all about the islands and their inhabitants, and, as a jaded biologist, that I would be intrigued but not stunned. But I was stunned. It’s one thing to read about these animals from afar, another entirely to see them in the flesh, fur, and feathers. It’s simply astounding to step onto barren, black, and dry lava islands teeming with life: dancing blue-footed boobies, iguanas so thick on the ground that you must avoid stepping on them, sea lion pups so friendly they will waddle into your lap, the weirdly primeval giant tortoises, and finches so tame they will alight on a stick held in your hand. Not to mention the Galápagos penguins and the sea turtles (I once swam with both, including sea lions). It’s a once-in-a-lifetime experience, one that both evolution mavens and anyone who loves animals (or lovely landscapes) must have. There’s nothing I’ve seen to compare.
*******

Reader Jason from Canada sent some odd but beautiful squirrels. Canada seems full of black and weird-colored squirrels (the Parliament grounds in Ottawa is full of black ones); I wonder why.

Here is a black squirrel with a blonde tail in Grange Park,Toronto (1 block north of City TV/Much Music HQ). We also had an albino squirrel in Trinity-Bellwoods Park which unfortunately died last year (down the street from the park there is a road “White Squirrel Way” that leads into the CAMH facility. We also have red squirrels in High Park and a few of the other forest areas of the city. The majority of squirrels are black and grey and a lot have different colour variations.

DSC_6019a

DSC_6035

DSC_6077a

Thursday: Hili Dialogue

May 28, 2015 • 5:49 am

I believe the book talk went well last night, though there were lots of questions from apparently miffed people, including one rabbi who said I needed to learn more about Judaism! (He didn’t tell me how my knowledge was deficient with respect to the thesis of my book.) I believe Jason Rosenhouse, who was kind enough to make the long trek to my talk from his Virginia digs, will write a report on his website about my talk, which I will link to in lieu of writing one myself. I also met several readers of this website I hadn’t known (lurkers, I think), one of whom informed me that she thought I was mean to Cyrus in these dialogues, and that I should respect the d*g more! Well, in Dobrzyn the d*g and the cat are playing Greek philosophers in the orchard, and this is a cute picture.

Oh, and lots of people said “Maru” and demanded that I draw a cat in their book. They must read this site, or have acquired the secret word in samizdat.

Hili: Are there still any genuine peripatetics in the world?
Cyrus: Probably just the two of us.

P1020822
In Polish:
Hili: Czy są jeszcze na świecie prawdziwi perypatetycy?
Cyrus: Chyba już tylko my dwoje.

Squirrels of a different color

May 28, 2015 • 5:00 am

by Greg Mayer

Squirrels are, of course, perennial favorites here at WEIT, being known as honorary cats. They also present a number of interesting phenomena of within and among population variation in easily observable traits like pelage color. Because these variations are often known even to casual observers, I often use squirrels as examples when explaining what species are. In eastern North America, gray squirrels, fox squirrels, ground squirrels, chipmunks, and woodchucks provide many informative examples of the differences within and among species.

We’ve had occasion to comment here on albino, parti-colored and black squirrels, all of which are gray squirrels (Sciurus carolinensis). I was thus intrigued when my Toronto correspondent sent along a photo, taken in Port Huron, Michigan, of a black squirrel with a brownish tail.

Gray squirrel that is balck with brownish tail.
Gray squirrel that is black with brownish tail.

The body looks like a typical melanic squirrel– black, although when seen up close, they often have some reddish/brownish in them– but the tail is brown! Black is usually the result of the pigment eumelanin, while browns and reds often are due to the presence of phaeomelanin, so melanics can have both pigments present. In the Port Huron squirrel, the tail (although not the underside of the base, which is black) perhaps has only phaeomelanin. There were “tons” of regular melanics in Port Huron, but just one with the lighter tail.

I have seen melanics and albinos in the wild, but I had never seen– in the wild, in a museum, or just in a photo– a melanic with a brown tail. I consulted a colleague with a great deal of field experience in Wisconsin, especially northern Wisconsin, and he too had not seen them. I was surprised to learn after consulting a standard reference (Fiona Reid‘s volume on mammals in the Peterson Field Guide series– highly recommended) that such squirrels are in fact well known, especially from further north in the range of the squirrel.

My Toronto correspondent also sends a photo of a black squirrel from Toronto itself. Black squirrels are quite common in Ontario: my correspondent writes, “[I]n Toronto, I feel as if I see a black squirrel every time I turn around!” The interest of the pictured squirrel is that it seems to have light spots on the forehead and back; she said it looked “spotted”.

Spotted black squirrel in Toronto.
Spotted black squirrel in Toronto.

You can see the white spot on the forehead; there’s another, just barely visible in this photo, in the middle of the back. I have never seen this pattern either. I did find though, through a link provided by Jerry, the opposite pattern: a photo of a white squirrel with darker spots on forehead and mid-back from Brevard, North Carolina, where white (and mostly white) squirrels are common.

A Brevard, NC white squirrel with some dark markings on forehead and mid-back.
A Brevard, NC white squirrel with some dark markings on forehead and mid-back.

The reptile-mammal transition

May 27, 2015 • 1:07 pm

by Greg Mayer

Update: An alert reader, has objected to the theory presented below, or at least the specific evidence used; he has proffered what he contends is “much more pertinent evidence”, which I append below.

Jerry posted a couple of days ago on a specimen of an early tetrapod, Ossinodus, which seems to have had a partially healed injury to the radius of its right forearm. The authors who described the injured specimen interpreted the injury as a fracture that could only have occurred on land, arguing that Ossinodus therefore is the oldest tetrapod that can confidently be said to be terrestrial. (The first tetrapods, from the upper Devonian, are considerably older than Ossinodus, which is from the following Mississippian subperiod of the Carboniferous; but these earlier tetrapods, which had caudal fins and functional gills, may not have been terrestrial.) Ossinodus is thus potentially an important point in the transition from fishes to amphibians.

Another major transition in the history of vertebrate life was that from reptiles to mammals, which we have discussed here before at WEIT. As important as the morphological changes which can be seen in the fossils, are the changes in ecology and behavior, which, along with environmental changes, lead to changes in the extent to which one group or another dominates the ecosystems of its time. Although mammals originated in the mid-Mesozoic era, it was not until the Cenozoic (colloquially known as the “Age of Mammals”) that the mammals became the dominant terrestrial vertebrates. Most ideas on the rise of mammals to ecological dominance focus on the fate of dinosaurs and other large reptiles at the end of the Cretaceous, when the disappearance of the latter may have been caused or accelerated by the impact of an extraterrestrial body. I was recently forwarded another theory, visually expressed, about how it was that mammals replaced reptiles as the dominant land animals on Earth.

https://i.imgur.com/ilRV9QO.jpg
A mammal and reptile engage in a vigorous contest for dominance.

And now, the more pertinent evidence:

Leo battles velociraptor.
Leo battles velociraptor.

I will allow as the mammal in the new evidence does seem to have a more dominant position over the reptile.

h/t: C. Mayer, J.B. Losos