Saturday, September 27, 2008
Recently Beverly asked me about bird vomit. In particular she wanted to know if the "material" ejected by the birds when it is used as a defensive mechanism was the same "material" used to feed the young.
I did a bit of digging and found out that prey derived stomach oils are used both as an energy source as well as a defensive/offensive tool, at least for petrels, the family of birds most often associated with defensive projectile vomiting. Oils are produced by both adults and chicks and it is indeed fed to chicks by the adults. The chicks also produce the oils as well.
Birds have 3 stomach-like organs as part of their digestive system - the crop (generally for quick food storage in seed eating birds), the glandular stomach, and the muscular stomach (for grinding food). The crop and gizzard are generally reduced in petrels and most of the digestion is done in the glandular stomach. All petrels except diving petrels (Pelecanoididae) are know to produce stomach oils and the ability to projectile vomit those oils and stomach contents is most developed in those species that nest in the open on the ground, such as the Southern Giant Petrel, which I have photos of here.
The oils are derived from the prey items of each petrel species and are thought to afford petrels a high energy, low volume energy source composed most often of wax esters and triglycerides. These oils may also retard digestion of food items and thus enable petrels to assimilate food over longer periods, which is advantageous for birds whose prey are distributed in widely spaced patches or whose young often endure long periods of fasting between meals. The oils may also provide water for fasting chicks through the internal combustion of the oils.
These oils are apparently quite effective in deterring predation and have been know to result in death of predators, particular bird predators whose feathers become matted and loose insulating value potentially resulting in death through exposure. Diving petrels are thought to have not developed these oils because they tend to forage close to breeding areas and nest in burrows.
Although it might seem like the loss of these oils while vomiting them at a predator may be maladaptive, the loss of life would most certainly be a greater impact to an individual that a loss of a meal. The evolution of this behavior may have also benefited petrels by giving chicks a way to independently defend themselves allowing both parents to forage when the chicks are younger therefor providing more food earlier in the chicks life, and nesting sites can be in more open areas, thus allowing expansion into habitats otherwise not available.
The petrel that I have worked most closely with is the Southern Giant Petrel, arguably the bird most adept in the art of projectile vomiting. They are large birds, nearly the size of a turkey and have a correspondingly large stomach. When disturbed they can project their oils about 2 meters. We called it "gack" and I can vouch for the fact that it is very oily, stinky, and persistent. Giant petrels are also well known scavengers, so the projectile often contains more than just prey derived oils! Their bills are well adapted to scavenging with the lower mandible shaped much like a curved wood chisel well suited to jabbing into a carcass; the upper mandible is sharply pointed and hooked to then grab and tear out chunks of flesh to wolf down.
Despite being known as the Antarctic vulture with photos often taken of individuals head deep in a recently deceased seal, these birds can be remarkably endearing. The birds I worked with had become accustomed to having researchers visit their nests rather often and although some individuals never did get used to us, others were quite accommodating. Often we were able to gently approach a nest and reach under an incubating bird to rotate the band on the bird's leg so we could read all the numbers on the band. One of my favorites was a pure white bird that often tried to move me under her with insistent downward nudges of her bill on my arm so she could incubate me as well as her egg.
Armstrong E. 1951. Discharge of oily fluid by young fulmars. Ibis 93:245-51.
Warham J. 1977. The incidence, functions and ecological significance of petrel stomach oils. Proceedings of the New Zealand Ecological Society 24:84-93
Thursday, September 25, 2008
NASA has apparently placed 90 yellow rubber ducks in the Jakobshavn Glacier near Ilulissat in western Greenland to help understand how glacial meltwater moves from the glacier (I know it's a long way from Arctic Bay but you never know!). There is a $100 US reward for the first duck found and smaller monetary amounts for subsequent duck discoveries. More here.
Tuesday, September 23, 2008
Much like the migrations of large mammals with their deadly shepherds of lions, hyenas, and wolves, the movement of large flocks of birds have their attendant ghost riders as well. The shepherds I see most often are the shadow followers of warblers and sparrows. As Dad says, when the White-crowned and White-throated Sparrows start appearing in the rose thickets and dogwood, the accipters are not far behind. Most often it is the smaller Sharp-shinned Hawk we find, perched in the corner of the yard, noticed after the sparrows instantly melt into the rose thicket and the Downy Woodpecker merges with the suet feeder.
Last week it was the larger Coopers Hawk that resulted in a silence in my backyard. It was a young, brown cloaked bird that emerged from the neighbords cottonwood and slipped into the plum in my backyard. It waited and watched and I was able to find it through a gap in the fading leaves. It slipped away, there at one glance, gone the next.
Saturday, September 13, 2008
Something about the bagpipes always gets me and it was wonderful to be sitting in the middle of the band as they performed in a horseshoe shaped formation in our friends backyard complete with a group of young ladies doing Scottish dances while the band played. One of our friends daughters had her birthday today and one of the pipers even played Happy Birthday for her. After they finished their quick set they boarded their bus on headed out on the town.
I am still kicking myself for not bringing my camera so you are going to have to settle for a photo from their website of the band performing a couple of years ago . They promised to come back for another barbecue next year so I will be sure to bring my camera then.
I know some people don't like the pipes but like I said, for some reason hearing bagpipes gets me emotional. Must be something about my heritage or attending Glasgow High School where we used to have kids playing bagpipes in the high school band. In fact, the only request I have for when I pass away is to have bagpipes played at my service.
Friday, September 12, 2008
A couple of weeks ago I found out the the local weed control district was going to be having a tour to look at an area up the lake where they had done some Salt Cedar control. I was interested in seeing the area but I also realized that it would be probably the only chance I would have to get out on the lake to look for birds this fall.
It payed off. One of the first birds I found was a Sabine's Gull. There were also thousands of Western Grebes, a few Common Loons, and Ring-billed, Franklin's, and California Gulls.
I hope I get to do this again and when I can spend some more time looking for birds.
Tuesday, September 9, 2008
This Ferruginous Hawk flew above me and was obviously looking at me trying to figure out what I was doing.
Adult Swainson's Hawk in lentil field
Juvenile Swainson's Hawk.
Sunday, September 7, 2008
First I found a couple of Red-tailed Hawks playing in the wind at the edge of hill. As I was taking a photo of this hawk it folded it's wings and dove on the other hawk below it - I just barely caught the hawk heading straight down on the next frame.
Next I watched the local display herd of elk for a bit. It is that time of the year and the bulls that chummed around all summer have now developed an intense dislike for each other. I watched this bull shepherd his small harem of three cows and two calves while the next largest, younger bull shadowed the group, trying to look innocent but never quite pulling it off.
Saturday, September 6, 2008
Friday, September 5, 2008
Thursday, September 4, 2008
The first item is a chance to help out with a small scale conservation effort directed at an endangered grassland bird. Earlier this year Charlie at 10,000 Birds was birding in Kenya and happened to get some good photos of the Endangered and range-restricted Sharpe's Longclaw (a bird that looks remarkably like our familiar Western Meadowlark). He posted his photos to 10,000 Birds and added that if anyone would like to use the photos for conservation of this species, he would be willing to provide them. One thing let to another and Charlie and 10,000 Birds is now trying to raise a small amount of money for conservation work on this species. Below is what Charlie as to say about the project he worked up or you can read more about it here. Please consider donating to this project (I did). I believe it is one of those instances where a little bit of money can go a long way and thanks to Charlie for recognizing the need and organizing this effort.
This really is a worthwhile (and achievable) project to help save a rapidly disappearing species. Chip in, or read more about the project and Dominic at http://10000birds.com/sharpes-longclaw-10000-birds-and-the-small-african-fellowship-for-conservation.htm"
Photo of a Sharpe's Longclaw courtesy of Charlie at 10,000 Birds.
The next item is a chance for you to provide a voice in how one of the largest National Wildlife Refuges in the lower 48 states will be managed. The Charles M. Russell National Wildlife Refuge is currently working on producing it's latest management plan, called a Comprehensive Conservation Plan (CCP). They are currently soliciting comments on their range of management alternatives and I encourage you to check out information on this plan here. The latest publication on the planning efforts can be found here (PDF, 2.66 mb). The cover has a great photo of a beautiful lady and her young son with a pair of rather large binoculars glued to his eyes and there are a few more photos of a group of birders in the document that may look familiar to some of you. One thing I have learned since working on federal planning and review efforts is the power of good comments so please take time to review the documents and consider sending the refuge your comments on their plan.
Next is a link that I was given by a friend of a friend after a few email exchanges and the revelation that I have a Flatcoated Retriever (Addie is still here and her usual Flatcoat self. I haven't posted about her in a long time but maybe now that bird season is here...) Anyway, the link is for a Flatcoat breeder not that far away from me with similar interests in dogs and birds. I need to get in touch with Andy and Liz but if you would like to see some photos of their gorgeous working Flatcoats check out their website here.
Addie earlier this spring.
And last, but certainly not least, is a photo from the first day of school for my getting taller-by-the-minute oldest son Benton. Plus a photo of Benton and Crean from earlier in the summer just for fun.