#larusoccidentalis

[ethanm8n]

Juveniles

August 22, 2024

Juvenile California Gull

Now that most of the local Olympic Gulls are out of their nests, scattered along beaches, docks and alleyways, I think it would be a good time to talk about juvenile plumages. I would also like to briefly explore the types of moult that young birds undergo in early life, particularly in their first year.

Juvenile Plumage

Nestlings in most species begin replacing their natal down in the nest in a process called prejuvenile moult, which results in juvenile plumage.* Juvenile plumages (and subsequent immature plumages, like those of larger land birds and gulls) are fascinating, fine-tuned to give a young bird the best chance of survival. Thrushes like American Robins are speckled with dots and teardrop patterns to confuse a chasing predator, while the muted grey and brown colourations of Larus gulls act as camouflage. In fact, as for adult birds, juvenile plumages serve multiple and often conflicting functions (e.g. predator confusion vs camouflage), which find balance through natural and sexual selection.1

Fledgling Swainson's Thrush. Notice the buff teardrops on the upperparts and speckled chest.

Formative Plumage

There is also a wide variety of moult strategies for immature birds. In most cases, juvenile feathers have to grow quickly, being semi-functional by the time the bird has left the nest. Because of this, these feathers are of lower quality than adult feathers. Combined that with the fact that most species have a longer delay between prejuvenile (first prebasic) and second prebasic moult than subsequent moults, many species have supplemental moults to maintain feather quality.2 The preformative moult takes place after, or even before, the prejuvenile moult has completed, producing formative plumage. In many songbirds, and small gulls like Bonaparte's and Franklin's Gull, this moult is limited to body feathers and some coverts, though there is much variation.

First cycle Franklin's Gull. This individual has some grey feathers appearing on its upperparts, marking the start of the preformative moult.

Alternate Plumage

Larger gulls (Glaucous-winged Gull, Herring Gull, Ring-billed Gull, etc.) do not have a preformative moult.** Whereas the prebasic moult is usually complete (replacing body and flight feathers) and coincides with the nonbreeding season, the prealternate moult replaces less feathers. Alternate plumage--think of it as alternating with basic plumage annually--is completed around the breeding season for many species, and is often when you see birds at their most colourful. Birds that take multiple years to reach adulthood still undergo this prealternate "prebreeding" moult--it just looks a little messy. When my local Olympic Gull Juveniles start developing grey feathers on their backs, that is the prealternate moult in progress.

First cycle Ring-billed Gull beginning its prealternate moult (light grey on upperparts).

I know I am throwing a lot of jargon around--moults, cycles and bears, oh my! If anything, this is just me, a novice birder, trying to express my excitement about such misunderstood and under appreciated subjects as the plumages of juvenile and immature birds and the process of moult in general.

Until next time.

*I might confuse a few people writing about H-P terminology and the WRP system in Canadian English. Hopefully more Old World articles begin to be written using these standards, trading in Life Cycle terminology, which has an initially shallow learning curve, with that which better accounts for eclipse plumages in ducks and variation in moult duration in neotropical birds.3

**Preformative moults actually occur in most birds, according to Pyle. However, it is not appreciable enough in the larus gulls I come across. I need to look into this further.

References

Jenni, Lukas, and Raffael Winkler. “The Biology of Moult in Birds.” Bloomsbury Publishing, 2020, pp. 10.

Pyle, Peter. “Identification Guide to North American Birds.” Part 1, Second Edition, Slate Creek Press, California, 2022, pp 16.

Wolfe, Jared D, et al. “Ecological and evolutionary significance of molt in lowland Neotropical landbirds.” Ornithology, Volume 138, Issue 1, 2021. doi.org/10.1093/ornithology/ukaa073

[anthropocenesketchbook]

#westerngull #larusoccidentalis #sciart #sketchbook #orcasisland #sanjuanislands #directwatercolor

[ethanm8n]

Second-third cycle Olympic Gull.

(Vancouver BC, April 26 2024)

[ethanm8n]

Gulls

March 19, 2024

“I was mugged by a gang of seagulls” reads the title of a Tripadvisor review for Granville Island1. “When I came outdoors [a] gang of seagulls attacked me and stole part of my lunch.” Anyone who has eaten a meal outside of the Granville Island Public Market will understand this frustration. Seagulls watch like sentinels from rooftops, above benches and dining tables, on the lookout for a loose pizza slice; grey-coloured seagulls beg near sitting diners, screeching incessantly. Some seagulls patrol the skies above, while others choose to stay close to the ground, walking around on webbed-feet, waiting for loose food items and handouts. It would be easy to overlook these birds as a nuisance—rats with wings, to quote the pelican from Finding Nemo. They may be kleptoparasites, stealing food from other animals, including lunching humans and unsuspecting tourists. But seagulls are so much more than just ratbirds. In the Salish Sea region, they humble the proudest of birders trying to make an ID. (Is that light grey-mantled gull with darkish grey wingtips a Western x Glaucous-winged Gull hybrid or a darker Glaucous-winged Gull? Does the slightly smaller, petite head indicate hybridization with a Herring Gull, or is it a female of another species? Is its eye colour dark or pale? How about the colour of the orbital rings?) Their increasing reliance on urban breeding grounds (e.g. rooftops) serves as a litmus test for habitat degradation, and also gives researchers an opportunity to study how fauna adapt to urban living. How does the diet of an urban dwelling Glaucous-winged Gull Larus glaucescens differ from one that spends its time in more remote areas? Do urban seagulls lay more or less eggs than their counterparts? What is the survival rate of their young in to adulthood? Researchers have been hard at work answering these questions2. One recent study flew drones above buildings in Victoria to study nest sites of Glaucous-winged Gulls, a wonderful example of new technology opening up more avenues for scientific inquiry3.

Before going further, I need to address a misnomer. Gulls belong to a diverse group of birds in the family Laridae, from the circumpolar, all white Ivory Gull Pagophila eburnea, to the grey-bodied Lava Gull Leucophaeus fuliginosus and coal-black backed Olrog's Gull Larus atlanticus in South America. (Melanin—the pigment responsible for skin colour in humans—is what gives darker tones to feathers. It helps resist sun bleaching, which is why gull species's upper bodies trend towards darker tones closer to the equator4.) The Heermann's Gull Larus heermanni is a true pelagic (literally “ocean”) species, individuals spending their days hunting for fish, rarely going inland. Then there is the California Gull Larus californicus, which breeds inland of the Western United States; and the Ring-billed Gull Larus delewarensis, prolific in most of North America, but rarely straying beyond coastal waters5. This is why you will almost never hear birders refer to seagulls as such. Many gulls are generalists, found in urban centres, prairies, rivers and lakes, landfills, open oceans and coastlines. Calling them seagulls would be a disservice to their enterprising nature, breeding on every continent, including on the fringes of Antartica. Many of these species have adapted to living in rapidly expanding human-made habits. We can conflate this success with the annoyance conjured up in many people's minds when they think of these birds: Their pervasiveness; their loud squawking; the mess they make with their guano; and their proclivity towards thievery. Perhaps the things humans find so irritating about gulls are actually what we hold most in common. But I digress. No birder or ornithologist worth their salt is going to call you out for saying seagull instead of gull. (If they do, they will bring it up benignly.) Gulls as a label in itself is taxonomically ambiguous, pertaining to several genera within the Laridae family while excluding terns, skimmers and noddies. Instead of splitting feathers over vernacular, try learning about local gulls in your neighbourhood (if you have any.) Download an app like Merlin or Audubon for quick reference if you stumble upon an interesting bird. Your local gull species may not have the vocal acumen of a Song Sparrow Melospiza melodia, nor the fantastically coloured plumage of a Wood Duck Aix Sponsa. For me at least, I find tremendous enjoyment in watching a second winter Olympic Gull walk past me, a collage of grey and brown and white; or seeing a first winter individual staring at me with those deep and dusky eyes, its first grey scapulars developing, like ash on a dirt road. Gulls are full of personality. I observe them trying to snatch fish from cormorants; pulling up worms from park grass; standing on volleyball pegs and tidal rocks, heads tucked in behind their backs and bodies rotating side to side as if to lull themselves asleep. Even the seemingly normal, mundane, sometimes irritating aspects of life can offer up wonders if you are patient. Gulls or otherwise.

References:

“I Was Mugged by a Gang of Seagulls – Granville Island, Vancouver Traveller Reviews – Tripadvisor.” Tripadvisor, 2011, www.tripadvisor.ca/ShowUserReviews-g154943-d156255-r120159573-GranvilleIsland-VancouverBritish_Columbia.html.

Edward Kroc. “Reproductive Ecology of Urban-Nesting Glaucous-Winged Gulls Larus glaucescens in Vancouver, BC, Canada.” Marine Ornithology, vol. 46, 2018, pp. 155–16.

Louise K. Blight, Douglas F. Bertram, Edward Kroc. “Evaluating UAV-based techniques to census an urban-nesting gull population on Canada’s Pacific coast.” Journal of Unmanned Vehicle Systems, vol. 7(4), 2019, pp. 312-324. https://doi.org/10.1139/juvs-2019-0005

Steve N.G. Howel, Jon Dunn. “Peterson Reference Guides to Gulls of the Americas.” Houghton Mifflin Harcourt, 2007, p. 25.

Birds of the World, https://birdsoftheworld.org/bow

[kmorgantini]

Western Gull #LarusOccidentalis (at Lake El Estero, Monterey Ca)