“TIS THE SEASON TO EAT DUCKLINGS,

Fa la la la la, they’re good for you.”

This just might be the spring song at the top of the Coyote Hit Parade. Ducks have been breeding for the past several months in the Pacific Northwest, and there is a steady supply of cute, fuzzy, edible ducklings. Mallards were first, and many of them have full-sized young now. They were followed by other species, including Gadwalls, the second most common breeding duck in western Washington.

Ducks lay clutches of around 8-10 eggs and incubate them for almost a month to hatching. Incubation begins when the last egg is laid, so the young all develop synchronously and hatch at about the same time. The female leads the ducklings from the nest off to a good wetland feeding area, watching carefully for predators.

She can warn her offspring to hide, but she can’t do much to protect them against the predatory mammals, birds, snakes, frogs and fish that might relish a duckling meal. A duckling might be a snack for a Coyote, a good lunch for a Mink, or an overstuffed belly for a Bullfrog.

The downy (cute) stage in a Mallard lasts about 25 days, and then they begin feathering out and enter their gawky “teenager” stage.  After another few weeks, they are fully feathered, and they can fly at around two months of age; most broods are abandoned by the female then or a bit before.

Males of most species of ducks desert their mates when incubation begins, but in city ducks, it seems that more and more males can be seen with their families, at least early in the season, and one wonders if there are genetic changes happening in these populations.

The males begin to molt out of their definitive plumage soon after leaving the females, changing to a female-like eclipse plumage and eventually molting all their flight feathers simultaneously. The Gadwall shown here is entering that plumage. After their brood has fledged, females also undergo a complete molt, although they don’t change plumage.

Meanwhile, predators are taking their toll. Rarely will you see a complete brood of ducklings. Instead, the numbers decrease week by week until there are often only a few left with any given female. Sometimes females combine broods, raising the level of predator awareness with two pairs of eyes, but the young still remain relatively unprotected.

In any case, all a pair has to do is raise two young successfully in their lifetimes to keep populations stable. Waterfowl populations as a whole are doing well, so those females must be doing something right! Perhaps it’s good that not all those ducklings survive, as wouldn’t we be knee-deep in ducks at some point?

Dennis Paulson

YES, WE HAVE VULTURES

We often think of vultures as big, ominous-looking birds sitting around the carcass of a lion-killed wildebeest in Kenya or lined up on rooftops next to a garbage dump in South America. But we have our own carrion-eating vulture in the Pacific Northwest, the Turkey Vulture (Cathartes aura).

Turkey Vultures occur throughout the tropical and temperate parts of the New World, from southern Canada to Tierra del Fuego. Those at the northern end of the range, in Canada and northern US, are migratory. Tremendous numbers of Turkey Vultures migrate through Mexico and Central America. The vulture migration over Panama in October has almost reached the status of a tourist attraction, as the birds wheel and climb above the high-rise towers of Panama City in the fall, along with Swainson’s and Broad-winged Hawks.

They return to Washington from their tropical wintering grounds in late March and April to occupy nest sites on cliff ledges or in broken-off hollow trees or other dark recesses, usually in remote areas well away from human disturbance. They lay 2 eggs that they incubate for about 40 days. The young remain in and near the nest for up to three months after hatching. Oddly, although commonly seen in the air, they are almost never seen at road kill, very different from the situation farther south.

These vultures are very often seen early in the morning perched with wings outspread, apparently to dry them out. Why this is so common in vultures and doesn't occur so much in other large soaring birds may be a mystery we never solve.

Turkey Vultures fly with their wings held up in a dihedral angle, which it turns out adds stability in turbulent air. They often fly close to the ground, so this is of great importance. As a wind current hits one side, that wing tilts up and the other down. As it tilts down, it approaches the horizontal, where lift is maximal, and that stabilizes it. Watch a vulture in windy conditions and see how it tilts from side to side.

Unlike most other vultures, Turkey Vultures have a well-developed olfactory sense. Field experiments have shown that they can find something as small as a dead mouse by its smell, even under a closed forest canopy. Watch a Turkey Vulture quartering on the wind, going back and forth as first one nostril and then the other picks up the smell of a carcass from upwind. By going back and forth as the smell gets stronger and weaker, they eventually home in on the spot.

At lower latitudes, where Black Vultures are abundant, they may use Turkey Vultures as their carcass finders, watching individuals of the other species and following them to the ground. The Blacks are also watching each other, so the stimulus from a descending bird spreads outward, probably for quite a distance. Blacks dominate Turkeys, so the Turkeys must be quick to take advantage of a “fresh” meal. In the forested tropics, the much rarer big white King Vultures may finally appear and scatter all the lesser birds.

Turkey Vultures have actually increased in the PNW in recent years, for reasons unknown. Are there more dead animals now? Are they being more successful on their wintering grounds? Were they reduced by DDT like so many other raptors and are still recovering? In any case, they are masters of the air and a pleasure to see in the sky.

Dennis Paulson

THE CHORUS OF THE CHORUS FROGS

Early every year in the Pacific Northwest a familiar sound rings out, telling us it is spring whether it seems that way or not. this is the “song” or advertisement call of the male Pacific Chorus Frog, Pseudacris regilla.

Most people recognize the call immediately as the generic frog call of movies in decades past. As this is a common frog (or at least used to be) in Hollywood, California, its call was incorporated into many a movie that needed frog calls as ambience. In fact the “ribbit, ribbit” sound has become the stereotype of frog calls.

These frogs come out of their winter dormancy very early in spring, when, to paraphrase Robert Burns, a young frog’s fancy lightly turns to thoughts of love. The only way a frog has to express itself in such a situation is to call . . . . and call . . . . and call. And that they do, with surprising strength.

When a male frog feels these stirrings, he heads for the nearest pond or marsh, usually in the evening but sometimes even during the day. On arrival, he jumps in the water and swims to what he considers a good position. Only the frog knows why it is a good position, but it probably provides a place to hold onto the vegetation and a place where he can be easily seen as well as heard. Interestingly, it is often the same male that calls first each evening.

He begins to call: ribbit, ribbit, ribbit, a creaky two syllables that carries at least a hundred yards or more on a quiet night. Another frog heads for the pond, either because hopping downhill in a moist environment will lead to water or because it homes in on the first frog. The second frog begins to call, perfectly insinuating its calls between those of the first. The two may sound quite different, so we hear ribbit, rabbit, ribbit, rabbit, ribbit, rabbit.

A third male begins to call, amazingly also able to insert its calls into the soundscape so they can be heard as distinct: ribbit, rabbit, robbit, ribbit, rabbit, robbit . . . the pace is speeding up, and there is no room for a fourth frog, but that one calls anyway. As the chorus swells, the individual voices become less apparent, even though the structure may still be there, but a female approaching the pond can easily distinguish the individual voices.

Females apparently choose males based on the vigor of their songs, and as the evening progresses, more and more males acquire a mate. The male clasps the female and stays with her while she looks for a place to lay her eggs. She finds such a place, lays a cluster of eggs, and the male fertilizes them.

The eggs hatch in a few days, and the tadpoles grow quickly on a diet of plant matter. After a few months, they finally absorb their tails and grow a set of limbs and are then ready to leave the pond. If they survive the year, they will return the following spring, and the pond will resound again with the chorus frog chorus.

Dennis Paulson

THE BIRDS THINK IT’S SPRING

This is the time of year when our resident birds begin to sing. Already I have heard Anna’s Hummingbird, Bewick’s Wren, American Robin, Varied Thrush, European Starling, House Finch, Song Sparrow, and Dark-eyed Junco singing around my house. On the other hand, the vast majority of migrant species have not arrived yet, and those residents that are singing won’t be breeding until some time in April.

Why don’t all birds breed at the same time? Well, an easy explanation for raptors is that their incubation periods are long, so it behooves them to breed before many other species, so they have eggs hatching at a time when food resources are high. As it turns out, the eggs of the early breeders hatch at a time when many local mammals are weaning young.

Some species, for example raptors such as Barn and Great Horned Owls and Red-tailed Hawks, have already begun their breeding cycles. A Northwest pair of Red-tailed Hawks could have a complete clutch of three eggs laid by March 20. The first egg would hatch in mid April, and young would be ready to leave the nest by the end of May.

The bird-eating accipiter hawks (Cooper’s, Sharp-shinned) begin to breed later than the mammal eaters, because the supply of naïve young birds doesn’t really kick in until May or June. A Cooper’s Hawk pair that lays the first egg of a clutch of four on April 15 would expect the first young to hatch on May 20 and the first young to fledge about a month after that. By the end of May there are great numbers of young, naïve birds in the surrounding woodland that can provide prey for a family of Cooper’s Hawks.

A Barn Owl that laid her first of six to eight eggs on March 10 would see the first young hatch on April 10 and fledge in about two months. By hatching time, great numbers of young voles would have emerged from their grass nests to forage in their myriad runways, and the parents can find plenty of protein for their growing young. Furthermore, a just-fledged owlet should have no trouble detecting and catching those furry snacks.

Mammal-eating owls such as Barn and Great Horned breed early, but insect-eaters such as Western Screech and Burrowing Owls breed later for two reasons. First, incubation and fledging periods are shorter for smaller birds, so there is no reason to start so early. More importantly, their prey does not become active until ambient temperatures allow activity. So these owls are laying their eggs in April and even May.

A Burrowing Owl clutch of eight eggs might be completed on April 15, when incubation would ensue. The eggs would hatch around May 15, and the young would be ready to leave the burrow by the end of June, when insects and lizards abounded in its nesting territory.

So the eggs of the mammal eaters hatch about a month before the eggs of the bird and insect eaters, just as predicted. Not only the wonderful adaptations of living organisms, but also their exquisitely fine tuning, never fail to impress me.

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