Blogger says farewell

When I started this blog in 2008, I would never have imagined it would have the kind of longevity or enthusiastic readership that it has. I thought it would be an outlet for occasional news and information and might not last all that long. Instead, it became my connection to many of you Seanetters, to collaborators, to students of dead bird identification on either side of the Atlantic.

Farewell from my accustomed blogging spot, alone in the dining room.

Because it has come to mean so much to me, it’s been difficult to come to my present decision. Since 2014, I have been a full time professor at my local community college. Because SEANET doesn’t count as one of my responsibilities in that role, I have to pursue any SEANET activities outside of my obligations to the college. This, as you might imagine, leaves very few hours in the week. Keeping the blog while also responding to your emails, and trying (trying) to analyze some of our data from time to time, has proven untenable. Since I do not want to stop corresponding with volunteers, or dredging up data for people who request it for their research, I concluded that the blog must be what I let slip overboard to lighten this little craft.

I want to say thank you to all of you, everywhere, who have read the blog, written comments, played the Dead Bird Quiz game, and otherwise made my solitary work a little less solitary. I feel what seems a disproportionate sadness over this; this blog has combined three of my great loves–writing, science, and education.

If I may flatter myself that some of you would follow my writing outside the proscribed bounds of seabird science, I do keep an intermittent naturalist’s/outdoor/ecology blog that you are welcome to stop into from time to time.

Thank you, thank you, thank you for over seven years of your company, your time, and your interest. I won’t ever forget it. -Sarah

Scrounging for cash

For an impoverished outfit, we don’t go begging for funds nearly as often as we ought, here at SEANET. I mean to rectify this, in part, today, with a specific plea.

Regular readers of the blog will know that I help out every summer banding gulls on Appledore Island in Maine. Each year, we are fortunate to have generous private donors who fund students to come out and assist us. This year, we are trying something new, and much more ambitious. Of the students who came out to the island for banding last week, we selected two extremely talented young women to spend an entire summer on the island not just banding gulls, but studying their diet, reproductive success, and a host of other ecological parameters. It’s something we’ve long talked about, and this is our pilot year.

Again, we have benefited from the incredible generosity of private donors in paying the steep fees to keep a person on the island for 10 weeks, but that brings me to why I’m here scrounging for cash.

Mary (right) and Taylor on island–these two are our chosen interns for 2016!

The internship funds we currently have cover room and board, transportation, and a very small stipend. We want our internship to be open to students of any means, and one of the students we selected (full disclosure of nepotism here) is my sister, Mary Everett. Mary is a full time student and she and her husband also have to work a substantial number of hours to keep the rent paid, groceries bought and all that. If Mary is to take 10 weeks of her summer off work to do this internship, she has to raise substantial funds to do so. Not only will she continue to have bills come due, but she is giving up the prime earning time of summer when she could normally make some extra money to get them through the school year.

If you can help out in any way, even a few bucks, we’ve set up an easy and secure site for you to do so. It’s the only time I’ll be on here asking, and every little bit counts. Please, help me ship my sister off to an island for a couple months!

Flashy color and honest signals

After the last Dead Bird Quiz featuring blue wing patches, it seems an apt time to address the structure and function of such color in birds. Blue is, of course, not the only color a bird may display; even outside the outrageous coloration seen in many tropical species like parrots, we here in North America are treated to many birds in these color classes:

Male scarlet tanager in Illinois (photo: CheepShot via Wikimedia)

Baltimore oriole depicted in the Wisconsin Bird Bulletin, 1906. (photo via Harvard’s Ernst Mayr Library)

In such cases, the colors in the feathers are built from dietary pigments, particularly carotenoids. Because the brightness of the color in the feather depends on the quality of the diet, such reds and oranges are termed “honest signals” of the quality of the individual–birds that are better foragers sport brighter colors. A female selecting a mate can use the brightness of a male’s plumage as an indicator of what sort of provider he will be, both in terms of genetic contribution, and, in species where males contribute parental care, how well he will provision the chicks.

Blue pigments, on the other hand, are not derived from diet, but are instead what are known as structural pigments. Proteins in the feather, when aligned properly, will reflect blue light back at the observer. These proteins typically “self assemble” and a more genetically fit bird would not be bluer than a lesser individual. Blue feathers either are, or they aren’t, as the conventional wisdom goes, and there is no spectrum of brighter or duller blue jays, or ducks, or what have you. There has been work to challenge this, focusing on what can affect the brightness of structural color. Feather mites, for instance, could damage or dishevel the feather, leading to a loss of brightness. A more fit individual might have fewer such parasites, and so the blue in these birds might appear brighter than a heavily infested bird. So a duller bird might be less fit, but is there any such thing as a “super blue?” A blue that is brighter than the average because that bird is fitter?

Turquoise-browed motmot (photo by Katja Shulz, via Flickr)

I encountered a study done on turquoise-browed motmots in Mexico on this subject. In this species, both males and females sport a blue tail with a racket shaped projection at the end, though the tail feathers are longer in males. The researchers analyzed the brightness of the tail feathers across the sexes and within the sexes, between individuals. They were interested in determining whether the brightness of the blue could, in fact, be linked to fitness in either or both sexes. Not only did the study address the variation in brightness across individuals, they also measured how quickly the feathers grew. Growth rate is considered an indicator of fitness since a bird’s energy reserves, and thus diet, determine how much new feather a bird can lay down in a day.

The research team indeed found that the brightness of the blue in the tail feathers was greater in birds whose tails grew faster, but only in males. In females, no link between the two was identified. It seems that, in males, blue may indeed be an honest signal of fitness. In females, the tail is shorter overall, and there is no correlation between brightness and growth. This is consistent with the hypothesis that the tail in female motmots is not used to signal fitness, but may serve a different purpose, like distracting predators while the bird makes a swift escape, or may simply be a genetic holdover between the sexes.

This subject of honest signaling also came up while I was preparing notes for a new course I am teaching this semester. My students will be looking at the dominance hierarchy in house sparrows. In these birds, the size and darkness of the bib in males is an indicator of his position in the hierarchy. Both males and females will defer to larger-bibbed males, and the dominance extends not only to access to mates, but to nest sites and food. Researchers have understandably been interested in what underlies these bibs. The black color of the bib is caused by the pigment melanin, which is expensive to manufacture. Because of this, black coloration is considered an honest signal, much as reds and oranges are, since only a well fed, highly fit individual, would have the spare energy to lay down that pigment. Since the bibs are tied to dominance behavior in males, testosterone seemed a likely target for analysis in this case. Interestingly, I found one study that showed no link between high testosterone and large, dark bibs. That study also noted that the bib is produced in fall when the birds molt, but is not used in terms of mate selection until the following spring. Testosterone levels can fluctuate substantially over that time, so birds that had high circulating testosterone in fall when they grew the bib may well have lower levels than their rivals come spring. So if females use those badges to select mates, and if rivals are choosing not to challenge another male based on badge size, they are not using a reliable indicator of testosterone at the time of breeding either.

A modest throat patch. Dark bills, unlike badges, DO show a clear link to testosterone levels. (photo: Adamo, via Wikimedia)

A more recent study following up on this work looked at testosterone again, but measured it at night rather than during the day. The results indicated that testosterone was, in fact, linked to badge size. Over the course of 24 hours, testosterone levels peak at night while the birds are asleep, and fall off rapidly as soon as the birds wake up. When measured at night, peak testosterone levels did correlate with individuals with the largest bib size. Perhaps, suggest the researchers, badge size reflects peak production of testosterone, rather than average level. This still leaves the question of seasonal changes–does this nighttime testosterone production hold true for the time of year when the badges are being grown, or only during the season when they are being used for breeding signaling? The plot thickens. Or, since we’re talking about dark splotches on birds, shall we say, the blot thickens? Sorry.

DBQ answers

I got quite a few responses to this one, and I am not surprised that our usual ringers were right in here with both the clear i.d.s and the one that is, at least somewhat, in question. All three birds are ducks which all respondents recognized. The first two are in one category–ducks with a bluish speculum on the wing. Bird C is in a category of ducks with blue on the wing, but with that blue located on the upper wing coverts rather than the secondaries as in Birds A and B. Let’s take the Bird A/B pairing first.

I like when I have an all duck quiz since I can use Samuel Carney’s Waterfowl Wing Key. When we follow through that key for a bird with blue or purple on the secondaries, we get to a junction point where we are asked what borders the blue or purple patch. If it is hemmed in with white both above and below (that is to say, with white on both the greater coverts and on the trailing edges of those blue/purple secondaries), then we have a mallard, like such:

Mallards in flight. (Photo by Ingrid Taylar)

In this photo, one can see not only the clearly bordered speculum, but another helpful feature for when you have the underside of the wing to look at as well–a mallard’s underwing is a clean, clear white. This is in contrast to our other candidate among the blue-speculumed ducks, the American black duck, which has a characteristic brown streaking on the underside of the wrist.

An American black duck (ABDU to friends) is generally described as having no white border, front or back, around the blue, though in many images and in some descriptions, one may see a faint pale trailing edge to the secondaries. It’s pretty faint though. Great, so that was easy, no? White borders: mallard. No white borders: ABDU. Not so fast (0f course). Because these two species heard we were having an easy time of their identification, they decided to hybridize freely. Given the slight chance of pale tips to the secondaries in an ABDU, we can look at the forward border of the speculum for a firmer sense of what is happening here. In an ABDU, there should be no white at all on the greater coverts at that leading edge of the blue speculum. So, where are we now with respect to Birds A and B? A shows substantial white both fore and aft. Bird A looks like a mallard decisively to me (my decisiveness here is augmented by back up from most of our respondents on this quiz). Bird B has what we might technically term a “meh” amount of white on that forward border of the speculum. It’s faint, but it’s definitely there. While some of our quiz players think ABDU on this one, others raised the possibility that this is one of those ABDU x MALL hybrids, and I am inclined to agree. Would that we had more of the bird to go on, but the features here do seem intermediate between the two species.

Now, to Bird C. This one is in the group of ducks with a large amount of blue on the upper wing coverts rather than the secondaries. It’s hard to know if the secondaries ever had much color–they may have, but as my next blog post will address, blues and greens in bird feathers are a trick of the eye, and in a disheveled specimen, those colors may be lost almost entirely. In addition, in some species, the secondaries are green and iridescent in males, but green and non-iridescent (dull) in females. I don’t see much that catches my eye in the secondaries of Bird C at all, but if there is any green there, I would say it looks decidedly non-iridescent to my eye. What we have to go on is the blue, and then some white on the greater coverts, though they do not appear entirely white–more dark spotted with white rims. In the group of birds with blue on the coverts and a white band on the greater secondary coverts, our best candidates are blue-winged teal and northern shoveler (both raised by our respondents). How to differentiate them? The number one feature all the field guides point to are the distinct white shafts of the primaries in northern shovelers. Take a moment to appreciate them in this image:

 

USFWS photo

As you can see in these images, the white band on the greater coverts in northern shovelers is uninterrupted, unlike the broken band with dark spots we have in Bird C. In addition, I do not see these obvious white primary shafts in Bird C. Taken together, these two features lead me to call this a blue-winged teal, and again, I draw unnatural courage in this i.d. from the fact that it came to me pre-identified by Craig Watson who works for USFWS down south, and also, so many of our crack dead bird experts told me they thought it was a blue-winged teal as well. I hardly ever see these, so I confess, I would not have come up with that right off the bat.

Next time, I will share with you what I’ve been reading about feather pigment, honest signals, and the flamboyant tails of motmots in the Yucatan.

Dead Bird Quiz: got the blues edition

It’s a monochrome world outside here in the north, and, though I am secretly wishing for snow so I can get some cross country skiing in, I do appreciate a spot of vibrant color. Thus, I have made these selections for the DBQ. Though they are not the most challenging ever, this will give me a window to talk about pigment in feathers when the answers are revealed, so look for that next week.

Here are our candidates (a phrase I hear a bit too often for my liking here in New Hampshire these days; I can’t travel 5 miles without tripping over a would-be President).

Bird A: found by Dan Tracey in Massachusetts in May.

Bird B: found by Ray Bosse, also in Massachusetts, also in May.

Bird C: guest Seanetter Drew Lanham, professor at Clemson, photographed this bird on New Year’s Day on Seabrook Island, SC.