Rigor Vitae: Life Unyielding

Monday, June 25, 2007

A PELICAN BRIEF

One of my vague blogging objectives is to chronicle some of the natural changes I see around me. As I mentioned the other day, I live in a big city surrounded by some of the least densely populated land in the temperate zone. Next month, Salt Lakers will celebrate the 160th anniversary of our city's founding, and during most of that short time, the natural world has been busy adjusting to that major insult. Behavioral changes often precede morphological ones, and it's often astounding how quickly behavior can change – among animals human and non-human alike. This state's still abuzz over it's first recorded human death by a Black Bear (Ursus americanus) last week, and a timid populace avoids the backcounty in droves, ignoring the fact that once they've parked their car at the trailhead, the dangerous part of the trip is over.

Last year I mentioned some local changes in pelican behavior, and it's high time for a serious update. The family Pelecanidae contains a single modern genus, Pelecanus, with seven species and nearly global distribution, occurring on all continents except Antarctica. The genus is well represented in Old World Miocene deposits. Today's pelicans are a uniform lot: fish-eating specialists with distinctively huge, flexible bills that anchor a skin pouch that serves as a fishing net. The African Pink-backed Pelican (P. rufescens), the Asian Spot-billed Pelican (P. philippensis), and the American Brown Pelican (P. occidentalus) are normally solitary foragers, but the other four species typically forage in groups of as many as two dozen individuals, forming a semicircle and corralling schools of fish, as the Eastern White Pelicans (P. onocrotalus) above are doing. As they fish, they raise their knobby wrists and gracefully rock them, often in unison. This fishing takes place mostly in the morning and evening, and is usually initiated by a single bird, who will take to shallow water and swim about, waiting for others to join. Once a group is on the water, they swim together, searching out a school of fish. Once an appropriate school is found, the birds encircle them, and plunge their heads under the water, opening their bill and distending their pouch. When a fish is caught, they bring their head to the surface and tilt it to drain the pouch before lifting their bill and swallowing their booty. When small prey is plentiful, the Australian Pelican (P. conspicillatus) sometimes uses its wings to propel itself forcefully across the surface, plowing through the shoals with its bill.
Most pelicans are cloaked in pale colors, like the American White Pelican (P. erythrorhynchos) and Eastern White Pelican above. Only the Brown Pelican varies from this color scheme. An iconoclast in more than plumage, the coastal Brown Pelican only strays far inland by accident. Brown pelicans forage just offshore, flying at modest altitude, usually under 15 meters. When a fish or school of fish is located, the bird crumples up and plunges into the water like a gannet. Its great bill is forced open, and the pouch is immediately filled with as much as 10 liters of water, and hopefully, a fish, which is brought to the surface and consumed after the pouch has been drained. These dives are quite spectacular, and attract the attention of all sorts of pirates. I once found a young Brown Pelican being beaten on by two adult birds as it cowered upon the water. The juvenile's pouch swelled to capacity with a captured fish. Seemingly unable to either release or swallow its recalcitrant quarry, the poor bird had little option but to sit out its fate. We watched it and the pair of older thugs for over an hour with no resolution before having to paddle on. I've seen gulls fly out to diving pelicans, to alight on their heads once they've popped to the surface—poking their own heads right into the larger bird's mouth to rip off a fish chunk or two.



Pelicans can't spend too much time on the water before their plumage becomes water-logged, and much of their day is spent loafing on sandbars or other favorite spots, occasionally preening themselves and grooming their pouch. Above left, an American White Pelican indulges in a glottal exposure, a practice peculiar to the genus, where the pouch is everted over the neck. This movement is also sometimes used to drain the pouch when fishing. Another peculiar pelican gesture is the "bill-throw" (above, right). This sometimes follows a glottal exposure, and seems to indicate a slight degree of unrest. Both of these gestures appear contagious, like human yawns, and the bill-throw may serve to communicate an intention to spread those long wings and take flight.

With the 1972 banning of DDT in the United States, the once decimated Brown Pelican has happily rebounded. The USFWS still classifies the entire population outside of the eastern US coast, Florida and Alabama as endangered, but a strong case could be made to delist the species at this point. The IUCN lists all pelicans as species of low concern except two vulnerable species: The Spot-billed Pelican has seen a serious decline recently, thanks to habitat degradation and human destruction of colonies for food, guano, and as an act of competition for fish. Central Eurasia's Dalmatian pelican (P. crispus) is protected in seven reserves, most importantly at Lake Mikri Prespa in Greece. The other 14 or so known breeding areas have seen substantial declines recently.
Brown Pelicans appear to adjust to people more easily than the other species. In coastal cities of the Southeastern US, like Charleston, SC, they are nearly as tame as pigeons, and in many Latin American fishing towns, rats might make the more apt simile. I have the good fortune to live near one of the biggest pelican colonies in the world. Gunnison Island, in the Great Salt Lake, is home to 4,000 to 14,000 breeding White Pelicans, depending largely on the fluctuating lake level. Isolated from the mainland, this sanctuary is home to but two mammal species, Gunnison's Deer Mouse (Peromyscus maniculatus gunnisoni) and the Gunnison Island Kangaroo Rat (Dipodomys microps alfredi), and is a State Wildlife Management Area, protected from human disturbance. I've never been to the island, but I paddled to a large colony of Eastern White Pelicans on the Senegal River (above), which was spectacular for eyes and nose alike. It's hard to imagine how the young birds could be packed more densely. As they mature, they form groups, or pods, of their own, which become the social unit in which they learn to live as adults. Since the Great Salt Lake has no fish, parent birds must journey to rather distant waters twice a day to provide for themselves and their young.
Last July, pelicans began fishing on a small pond in an urban park near my home. This year, they returned in Late May, and I've spent some time watching them, trying to make sense of their behavior. This pond, a popular duck-feeding site, is perpetually filled with well-fed Anseriformes, as well as nitrogen, which indirectly feeds a surprising density of Carp (Cyprinus carpio), Fathead Minnow (Pimephales promelas), and other fish. It is also only about ten miles from Gunnison Island, a fraction of the 30-100 miles the birds are used to traversing. The only challenge the pond presents the pelicans is great human activity, to which the pelicans are adjusting, as evidenced by another lawnmower photo (above). Pelicans from Gunnison Island have also begun fishing on a pond (often referred to by the non-ecologically oriented as a "water hazard") on a nearby golf course. On the morning of July 15, I took a photographer friend to the park, but only saw four birds, where 22 had been two days earlier. I speculated that a dog or drunk might have frightened most of them off, but for the following week the birds were mostly absent. I believe this is coincident with the hatching of their eggs and intensified responsibilities at the colony. Of course, they still must fish, and why they stopped doing it here isn't obvious to me.


Whatever the case, their visits are becoming more frequent now, with each day. At 9am this morning there were 6 of them. The literature I've seen describes White Pelicans as strictly diurnal, but the peak feeding here takes place in the middle of the night, when there is less human activity, and more light than one would have seen here 200 years ago. Their beautiful feeding ballet is even more dramatic in the dim of midnight. Birds even fly to and from the pond at 3am, across a route well-lit by Salt Lake City light pollution.

I'm ashamed to say I've yet to execute a painting of one of these fascinating birds. For now, I can only illustrate this post with photos and one dinky little Brown Pelican in the background of this San Esteban Island Chuckwalla.
____________________
All photos by CPBvK, taken in Salt Lake City, Senegal and Florida
lower: SAN ESTEBAN ISLAND CHUCKWALLA (2006) acrylic 30" x 20"

11 Comments:

Anonymous Brian said...

Interesting post!

A minor thing though; Elopteryx is no longer seen as a pelecaniform, or even an avian. It is generally considered either a troodontid or an alvarezsaur.

5:00 AM  
Blogger cpbvk said...

Thanks, Brian. So hard to keep up with the paleontological concensus! I've edited my piece to reflect your correction.

6:21 AM  
Anonymous Roger B. said...

Fascinating. Did you hear about the pelican that swallowed a pigeon in St James's park, London? The story was reported last year on the BBC News website.

9:15 AM  
Blogger burning silo said...

Wonderful post! Very interesting observations of the white pelicans in your area. That does seem odd about them feeding at night, but it seems that creatures will do whatever they have to in order to adapt to the presence of humans. There seems to be a great variation in their tolerance of humans as well. Last autumn, a friend and I visited the white pelicans in the Tule Lake area of n. CA. They seemed very nervous. Of course, it turned out that they had a good reason to be. I had checked to make sure that the week of our visit would be before the fall duck hunting season. However, little did I know that there was such a thing as a "youth hunt" a few weeks before the regular hunting season... and we arrived just as it began. It was like a war zone there with the poor pelicans, egrets and other birds flying from one part of the lake to the other trying to get away from the gunshot racket. As you might guess, we didn't get too much of a chance to enjoy watching the pelicans. Luckily, we did run into some in later in our trip. Saw lots of brown pelicans flying south along the California coast and shot some little movie clips of them diving into the surf after fish. As you've mentioned, the gulls were landing atop the pelicans trying to steal their catch. Beautiful birds. I wish it weren't so far for me to travel to see either species.

4:56 PM  
Blogger cpbvk said...

Roger: Yes, I'd forgotten about that article and the bizarre photograph! How common is it for Eastern White Pelicans to haunt parks in London?
Burning Silo: Thanks! White Pelicans were very wild birds here until the past couple of years.

7:55 PM  
Blogger coturnix said...

Pelicans may be coming back to Serbiabr/>
And I'll be at Salt Lake City airport for about an hour on Thursday morning...

3:42 PM  
Blogger cpbvk said...

Rats!! I'm in Los Angeles--otherwise I'd come out and buy you lunch at the airport Chili's.

5:53 PM  
Blogger coturnix said...

Well, I'll be in San Francisco for a month. Perhaps there is a way we can connect somewhere in California in July. Or in Chapel Hill, NC in Jaunary....

11:27 PM  
Blogger Darren Naish said...

Have only just seen the reference to Elopteryx: funnily enough, I (and Gareth Dyke) published the 2004 paper revisiting this taxon (another paper, by Sylvia Hope, looked at the fossil anew in 2002). I'm confident that it is a bird, but there's no reason to think it anything to do with pelecaniforms. Brian's reference to troodontids and alvarezsaurids refers instead to Heptasteornis, found in the same Upper Cretaceous deposits as Elopteryx.

Anyway... neat post. We had native pelicans here in the Uk in the recent past but, alas. And I like your description of brown pelicans 'crumpling' during a dive: what they do is both awesome, and incredibly stupid looking.

11:33 AM  
Anonymous RedondoManChris said...

I am seeing some large birds at night feeding in the surf zone off my beach in Redondo Beach CA. (Near LAX)
We think they may be pelicans about 10 to 20 but its dark so we cant see the bills or heads.
Do pelicans feed at night?
Or would this be a new adaptation to the city lights providing nightly luminessence for a new feeding behavior.

3:41 PM  
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7:33 PM  

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