BROWN PELICANS IN WASHINGTON

When I moved to Washington in 1967, Brown Pelicans were rare in the state. Formerly common and widespread on all coasts of the US, their populations had crashed over a period of decades. Only after some time and much research did the cause become clear. Beginning soon after the Second World War, DDT was developed as the first of the modern synthetic pesticides. Within a short time, it had been liberally applied to crops all over the continent and to settled areas to combat the mosquitoes that transmitted diseases such as malaria.

DDT accumulates in tissues and becomes concentrated as it passes up the food chain. Fish picked it up from the water and passed it on to the pelicans that ate them, concentrating the chemical in pelicans more and more. One of its byproducts, DDE, interferes with calcium metabolism and as a consequence, the birds weren’t able to produce sufficient calcium for their eggshells. The thin-shelled eggs cracked when the adults attempted to incubate them, and reproductive success dropped precipitously all around our coasts.

The consequences of using this pesticide became so obvious that in 1972 the Environmental Protection Agency banned its use in the US. Fish took up less of it, eventually pelicans were pretty much free of it, and their nesting success improved greatly.

By the end of the 20^th Century, Brown Pelicans had become common again on the Pacific coast and were coming up to Northwest waters in numbers never seen before. Now thousands of them visit our outer coast every summer to take advantage of fish populations apparently greater than those around their breeding grounds in southern California and Mexico. A small number of birds make their way all the way down to southern Puget Sound, and a few even stay through the winter now.

Our pelicans are a good mixture of adult birds with white heads and dark underparts and juveniles with brown heads and white underparts. They roost in large flocks on sand islands, jetties and piers and launch into the air to feed after long sessions of resting and preening.

This unmistakable bird is an aerial plunge diver. Single pelicans, sometimes in groups, fly several meters above the water and, when they spot a fish or school of fish below, they fold their wings and drop like a plummet, piercing the water with their long bill and almost completely submerging. When the bill reaches one or more fish, it opens and water rushes into the huge pouch. The pelican lifts its head and lets the water drain out, keeping the fish inside to be swallowed.

Heermann’s Gulls, breeding in the Gulf of California, also move north along the Pacific coast, becoming common in Washington waters while the pelicans are here and then moving south again in late fall.

When a pelican dives, it may be accompanied by one or more of these kleptoparasitic gulls. If a fish falls out of a pelican pouch, a gull is often there to grab it.

Dennis Paulson

WHAT'S WITH THE WHITE BIRDS?

We become so used to seeing birds such as robins and chickadees and sparrows that we notice right away when one of them is oddly colored. The abnormal color variations that are seen in birds often are the result of mutations that involve the reduction or lack of melanin pigments. When melanin is reduced, dark feathers become paler, even whitish. When melanin is absent, feathers are pure white.

Albinism involves a complete absence of melanin and usually results in a pure white bird with red eyes. The melanin pigment that gives birds brown eyes is absent, so the red blood is visible through the transparent cornea. This mutation does not affect other pigments, so if a bird has carotenoid pigments coloring it red or yellow, that color may remain.

Leucism is different from albinism in that it may affect all pigment types, reducing their concentration to produce a paler bird or eliminating them entirely to produce a white bird. This can occur in some or all feathers, making some birds a patchwork of normal and white or whitish feathers. A bird that is white with brown eyes is leucistic.

Odd variants are typically seen in the most common birds, so even when such a mutation is rare, we see enough individuals to eventually encounter a funny-looking one. Robins that were pale overall have been reported with some regularity. Dark-eyed Juncos are often reported with scattered white feathers, even a head pattern somewhat like a chickadee; pure white ones are much rarer, perhaps in part because they are very conspicuous to predators and don't last long! You can see why these mutations would remain rare.

Some populations of Black-capped Chickadees in the Seattle area have persistent leucistic genes, and individuals are seen year after year in a neighborhood with different combinations of whitish caps and backs and white outer tail feathers (looking a bit like a junco as they fly away). Apparently chickadees don't have enough visual predators to eliminate these genes entirely.

I know of at least four male Red-winged Blackbirds in Washington that had plumage almost identical to the one shown here. Apparently that leucistic mutation is widespread in the genome of this species, at least in the Pacific Northwest. Is this some basic blackbird color pattern that is suppressed by the males' black pigment?

Leucism can be hard to detect in birds such as gulls that are already gray and white, but a pure white one like this Ring-billed Gull usually indicates this mutation. Remember that egrets and swans aren't leucistic; they just evolved white plumage, obviously advantageous to them.

Dennis Paulson

EXTENDED PARENTAL CARE IN BIRDS

You may be surprised to see obviously immature (brown) gulls at the waterside at this time of year vigorously begging from some nearby adult. You can recognize begging by the bird's throwing its head back and giving loud, high-pitched calls. You may be even more surprised to know that the adult isn't necessarily the parent of that young bird. You may not be surprised to see that the adult ignores the young or chases it away if it remains persistent.

This begging behavior continues into the winter and even to the next spring in some Glaucous-winged and Western Gulls and their hybrids. After all, they have begged for food from their parents for several months, and the behavior is hard to turn off—especially if they are hungry!

Extended parental care after the young have left the nest area is rather rare in birds and seems to be restricted mostly to fish-eaters. It is not easy to catch fish—no bird has evolved a rod, reel, hook and line for the job—so a young bird just starting out to learn how to do this may have a difficult time of it. So although we see these gulls trying to get a little extra parental care, they don't usually get it.

However, young of some other types of birds are successful beggars well after the breeding season. Several species of crested terns have extraordinarily long dependence on their parents after fledging. Juvenile Elegant Terns fly around with their parents for up to six months or more, beg from them, and are fed.

Juvenile frigatebirds may return to their nesting colony for as long as a year after leaving the nest, to be fed by one or both of their parents. Frigatebirds forage by capturing squids and flying fishes at the sea surface, and they have to be very effective at scooping one of these fast-swimming fish from the water. Thus it takes a long time for the young birds to be effective foragers.

Tropicbirds also feed in the open ocean and on the same types of fishes and squids as frigatebirds, although they plunge into the water at high speed to capture them rather than picking them up with a long bill. Interestingly, tropicbird parents do not feed the young postfledging. Perhaps they should, as frigatebirds are thought to have low juvenile mortality for a seabird, presumably because of the extra help they get from their parents.

Dennis Paulson

BLACK-TAILED GULL IN COMMENCEMENT BAY

In the fall of 2009, a Black-tailed Gull (Larus crassirostris) showed up roosting on a log boom on the east side of Commencement Bay, near Tacoma. It was found on October 13 by Charlie Wright and remained for about a month, seen almost daily until November 7. I remember that date well, as it was seen that morning. That afternoon, Netta Smith and I were finally able to accompany Shep Thorp in his boat, the best way to see the gull, but we were unable to find it. It had presumably headed south with the large numbers of California Gulls that had been present until that time.

In the fall of 2011, presumably the same bird showed up at the same spot. First seen by Shep on September 14, it was still present as of November 4 but may have departed soon after that. During both of its visits, this bird was seen by many enthusiastic observers, mostly at a distance of several hundred yards, spotting-scope range. By far the best way to see it was to go out in a small boat and circle the big log boom on which it roosted daily with hundreds of other gulls.

On November 4, Netta and I brought our kayak down from Seattle and launched it from the Gilmur access point on the bay. Very quickly we found the Black-tailed Gull and captured a few mediocre photos. Then something spooked them, and a bunch of the gulls took off. We saw our bird head across the bay and disappear in the distance, very disappointing. But we weren't discouraged, as the day, although threatening rain, had turned beautiful, with the low afternoon sun illuminating the maple-covered hillside in front of us.

We maneuvered the kayak around the log boom and found a place to enter it, giving us better light for photography. The boom was covered with gulls over much of its length, with photo ops abounding. Double-crested Cormorants roosting on it didn't like us at all, and they took off when we were a hundred yards away. Harbor Seals watched us but stayed put until, in a few cases, we got too close for their comfort level. The gulls just mostly sat and watched us paddle or drift past as close as 30 feet from them. They are surely used to curious kayakers by this time.

The most abundant gulls on the boom were Bonaparte's and Mew, at least several hundred of each. Among them were dozens of California and a few Thayer's and Glaucous-winged. We scrutinized the flock carefully and were able to find no other species. While slowly moving around the boom, we found to our delight that the Black-tailed had returned. We were able to get photo after photo of it as it watched us; it often rested with eyes closed, comfortably napping. When we got a little too close several times, it hopped onto another log, giving us the opportunity to photograph it with a different species.

Among the hundreds of gulls, the lack of immatures was noteworthy. There were no immature Bonaparte's and only a few immature Mew and California, a far lower proportion than would have been in their populations. Obviously immature gulls were not using Commencement Bay, or perhaps they weren't roosting. Do they have a harder time finding enough food and therefore have to continue foraging for a longer time? That makes sense, and the timing of mature vs. immature gulls at roost sites would be an interesting research project.

Another point of interest was the variation in leg color in the adult gulls. We noted such variation in Bonaparte's, Mew, California, and Thayer's, usually from duller to brighter. Bonaparte's varied from pale pink to red-orange, California from yellow-green to blue-gray. Thayer's are supposed to have rather bright red-pink legs, but one adult had very pale whitish-pink legs.

In any case, my luck had changed; it turned out that this was probably the last time the gull was seen!

Dennis Paulson

THE GULLS OF PUGET SOUND

Gulls can be best viewed where we concentrate them, anywhere from fast-food restaurants (French fries are a favorite) to waterfront parks (white bread a staple of the menu) to a meat- or fish-processing plant where they relish the offal, awful as it is. For the most part, the large gulls dominate these assemblages, although if there are few of them, smaller species may be in attendance. The smallest species, Mew and Bonaparte’s Gulls, have different feeding habits and are not part of these spectacles.

As pointed out in a previous blog, the Glaucous-winged is the most common and certainly most ubiquitous gull in Puget Sound. It and the much smaller Mew Gull are the ones you see everywhere throughout the winter. During spring and fall migration, large numbers of Bonaparte’s Gulls appear, and during fall migration there are even larger numbers of California and Heermann’s Gulls.

In addition to these five species, several others are seen in much smaller numbers. Thayer’s and Western Gulls are uncommon during winter, Herring and Ring-billed Gulls even less common. After these nine regularly occurring species, any other species is much rarer. This discussion will concern itself with adult plumages; the immature plumages are usually quite different.

Heermann’s Gulls (Larus heermanni) are medium-sized and stand out by their entirely gray body and black tail; the bill is red, the legs black. In breeding season, the head is white, but we don’t see it in that plumage, as it is a fall visitor from breeding colonies in Baja California. It is more common in the northern part of Puget Sound, mostly in September and October.

Bonaparte’s Gulls (Larus philadelphia), usually seen in migration but remaining for the winter in small numbers, are easily distinguished by their small size, black bill and red legs, and extensively white wingtips. In breeding plumage, they have a black head. They tend to be in flocks, sometimes large ones, and they often feed along convergence lines, or “tide rips.”

All the other gulls have gray mantles, yellow bills, and white heads, bodies, and tails in breeding plumage. Mew Gulls (Larus canus) are the smallest of these, not much larger than Bonaparte’s. Adults have thin, almost pigeonlike, yellow bills and yellow legs. The eyes are brown, the mantle (back and upper surfaces of wings) medium gray. In nonbreeding plumage, the head and neck are strongly marked with gray. The extreme wingtips are black, with large white spots that furnish a characteristic field mark. Like Bonaparte’s, this species is most commonly seen feeding along convergence lines but is common and widespread throughout the region in winter.

The next larger is Ring-billed (Larus delawarensis), with mantle paler gray and contrasty black wingtips. The white tip spots are smaller than in Mew. The bill is yellow with a black ring, the legs yellow, and the iris yellow. This freshwater species is only occasionally seen on Puget Sound but is noteworthy for its very contrasty markings.

A bit larger, the California Gull (Larus californicus) is patterned about like the Ring-billed but has a darker gray mantle, like the Mew, and brown eyes. Note both mantle color and eye color alternate with progression from Mew to Ring-billed to California. The yellow bill features a black spot in front of the red spot characteristic of all the larger species.

The rest of the regularly occurring gulls, larger yet, have yellow bills with a red spot on the lower mandible and pink feet. Thayer’s (Larus thayeri) and Herring (Larus argentatus) are very similar, both with pale gray mantles and less black at the wingtips than either California or Ring-billed. Herring always has a yellow eye, Thayer’s usually a brown eye, but the eye is pale in some individuals. Thayer’s is slightly smaller, with a distinctly smaller bill and more rounded head shape. The wingtips of Herring are blackish above and below, while in Thayer’s, there is not only less black but it shows up scarcely at all from below. So wingtips black above and pale below are characteristic of Thayer’s.

Finally, the two largest species, Glaucous-winged (Larus glaucescens) and Western (Larus occidentalis), differ primarily in mantle and wingtip color. In Glaucous-winged, the mantle and wingtips are gray and darker gray, in Western dark gray and black, respectively. Very different-looking birds, they unfortunately (for the birdwatcher) hybridize freely in the Puget Sound area, and the hybrids come in all shades of gray. These have been called “Olympic gulls,” and they complicate field identification. The wings are always more uniform than they are in Herring and Thayer’s, in which the light gray mantle and black wingtips contrast strongly.

Western Gulls have slightly larger bills than Glaucous-winged and are more likely to have yellowish eyes. The skin around their eyes is yellow, the same in Glaucous-winged is pink. But again, the hybrids complicate the issue. Western is much less common in Puget Sound, but there are pure Westerns along with the hybrids. A pure Western usually retains a white head throughout the winter and doesn’t acquire a black smudge on the red bill spot as does Glaucous-winged.

See the Slater Museum’s gull web page (http://www.pugetsound.edu/academics/academic-resources/slater-museum/biodiversity-resources/birds/identification-of-pacific-nort/) for more images and further information on identification.

Dennis Paulson

THE COMMON SEAGULL

Seagull? Everyone knows what a seagull is, but why do we use that name for them? They are gulls, GULLS. We don’t have “seaducks” or “sealoons” or “seaterns,” so why “seagulls?” I don’t know, but I’ll never stop asking that question. Although all of them visit the sea for at least part of the year, more than half of the gull species breed on fresh water.

On Puget Sound, there is one very common gull, the Glaucous-winged (Larus glaucescens). In winter, most of the large gulls you see are Glaucous-winged, just as most of the small gulls are Mew Gulls. A moderate variety of species make up the other few percent.

Although in winter they wander inland to near-coastal freshwater lakes and well up the larger rivers, Glaucous-wings are basically marine birds. They breed throughout the protected marine waters of the Pacific Northwest in good-sized colonies on islands and scattered as single pairs at ferry docks or on rooftops. On the outer coast, the Glaucous-winged is replaced by the Western Gull as a breeding species.

Each pair nests in a scrape on the ground, lined with grass, twigs, and anything else that can be found in the limited nesting territory. The female usually lays three eggs totaling about 10% of her body weight, the last egg laid a bit smaller than the others. Both sexes alternate incubation for a period of about 27 days. Hatching takes a surprisingly long time, 2-3 days from pipping (first crack appears) to completely out.

The adults quickly begin to forage for the young, foraging trips lasting several hours. Prey items are brought about 10 times/day to a nest of three young. The young grow rapidly and are able to fly at about six weeks of age. They typically leave the colony at about eight weeks but are fed by the adults for some time afterwards, even well away from the breeding site. Young birds will beg from their own parents and other adults well into the winter, with diminishing returns.

Fully fledged juveniles are brown, coffee-with-cream colored with fine markings on most feathers. The wings and tail are very slightly darker than the body feathers and relatively unmarked. The bill is black, the legs dull pinkish. Limited molt begins during the fall, and the brown feathers of the back are replaced by gray.

Large gulls, including this species, seem to molt during a large part of the year, so plumage changes signaling a transition from immaturity to maturity occur not only between years but within years. The largest gull species take about four years to reach maturity, and their plumage changes throughout that time.

A typical first-year gull is brown, like the Glaucous-winged described here. By the time it is a year old, certain changes are evident in its plumage. Typically the mantle (= back) has become some shade of gray, and white feathering is increasing on the head and breast. The bill becomes pale (pinkish) at the base. The rest of the body and wings and tail look about the same.

By the second spring (about 20 months old), much more of the head and underparts are white, the bill has more pale color at its base, and gray feathers are appearing in the wing coverts. The wings and tail are still the same shade of brown, although both have been molted once.

By their third spring, Glaucous-winged Gulls look much more like adults. The bill has dark markings restricted to the tip and may be starting to turn yellow. Most of the head and body feathers are white (except for dark streaks and smudges on the head and neck). The wings are largely gray, the primary feathers with slightly darker tips and restricted white spots at the very ends. The tail is white, with or without gray spots toward the ends of the feathers.

One of these birds could easily be mistaken for an adult, but the white primary tips are more restricted, there is often a dusky wash across the upper surface of the wings, and the bill usually has a dark tip or subapical ring. there is much variation in plumage at this age. Some individuals look more like two-year olds, others more like fully adults. A small percentage defy categorization.

When the gull is mature, it has an entirely white body and tail and gray mantle, with slightly darker wingtips with white spots in them. The iris is brown, the bill bright yellow with a red spot on the lower mandible, the feet pink. The circumorbital skin is also pink. In nonbreeding plumage, the head and neck are suffused with dusky markings, and a black smudge appears on the red bill spot.

Back in the 1950s, a small group of these gulls from the Protection Island colony were raised to maturity in captivity by Zella Schultz of Seattle Audubon Society, and the variation within any given year class was surprisingly great. This is presumably because different birds have different hormone levels and apparently molt at slightly different times and/or with different degrees of completeness.

That tremendous variety of gulls that we see out there is caused, at least in part, by the gradual plumage change from young to adult in each species. Learn it in the Glaucous-winged Gull, and you will feel a sense of satisfaction at having made complexity somewhat simpler.

Dennis Paulson

IT'S TIME TO MOLT

All birds have a complex coat of feathers, thousands of them, which they use for insulation, display, camouflage, and flight. Look at a feather closely and you’ll see that it looks flimsy, yet it does its job very well by meshing with others of its kind. Flight feathers can hold up birds such as Trumpeter Swans that weigh in excess of 30 pounds and provide thrust and lift for continuous flight in birds on migrations that extend thousands of miles.

But these feathers, while strong, are not indestructible. Inexorably, a feather wears over its lifetime, and if a bird grew only one coat of them, eventually wear would take its toll. If not naked, a bird would look rather frazzled. Over time the feathers would lose their strength and insulating ability as the microscopic structures that hold them together wore off. Look at the same feather when about a year old, and you can easily see that wear. This Little Gull wing in the Slater Museum collection, from a one-year-old bird just molting into its second set of wing feathers, shows you how worn feathers can become before they are replaced.

The solution to this problem is the annual molt that all birds undergo. All the feathers on the body are replaced each year, usually soon after breeding, which would be in fall in our north temperate zone. Not only are the contour feathers of the body replaced, but all wing and tail feathers are replaced as well, except in the very large birds in which this isn’t energetically possible (see next blog post).

It takes a lot of physiological energy to grow a feather, so molting is a fairly slow process. A complete body molt takes as long as a month for an average songbird. Individual flight feathers take about three weeks to replace completely, so a complete wing molt may take a month or more. These constraints are very important to migratory birds, as they may not be able to migrate until they have finished growing all their flight feathers, and they molt only after breeding, with its own energetic demands, has been completed.

Wing molt is typically sequential. The innermost primary is shed, and its replacement begins to grow. Before it completes its growth, the second primary is shed and its replacement begins to grow. Etc. The molt progresses out the primaries and, at some point, begins in the secondaries, where it moves from the outermost (adjacent to the primaries) inward. This gull is in the middle of primary molt, with the two outermost feathers from the previous generation and the feather just in from those growing in. You can also see that some of the outermost secondaries have been shed.



This adult Black Turnstone shows body molt (worn brownish feathers being replaced by crisp blackish ones) and wing molt (worn brown primaries and newly grown blackish ones, with a gap where the intervening feathers have been shed and are regrowing). Most birds would look something like this in fall.

Of course, in birds that change plumage color between breeding and nonbreeding times, molt of the body feathers must occur twice each year, spring and fall. This molt is one of the most obvious ones to those of us who look carefully at birds. This juvenile Short-billed Dowitcher is just beginning its molt into its dull first-winter (much like adult) plumage; the scapular feathers are often the first to molt.

Dennis Paulson