Hi everyone,
I was wondering about the molt timing for Common Loons, Red-throated Loons, and Horned Grebes in particular, and loons and grebes in general. Will they molt on winter grounds before heading to breeding territories, and if so how long after molting will they tend to stick around for? My impression from what I've been able to find is that the loons do molt before, but the grebes will molt after. Also if anyone knows of a good resource for finding out information on molt timing of all types of birds, I would love to know of it. I've found some good places to photograph these species on wintering grounds and am considering whether I should try to make trips back late in the season or whether I am better off waiting until I have a chance to see these birds on their breeding grounds (which won't be this year).
Thanks in advance for any information!
Robert Rommel
Hi Robert- I'll have to do some research on this. Moult is complex and I doubt that loons and grebes are similar as they are unrelated.
My best source for moult information is the Birds of North America (BNA) project. BNA is available on-line for a modest subscription. Years ago I wrote the BNA account for my beloved Brown Noddies and have just finished co-authoring the revision for Ring-billed Gull. Here's the BNA link:
Sorry for the delay in getting back. Info below from Birds of North America.
Molt in Common Loons is complex and not completely understood. The moult from winter (Basic) to summer (Alternate) plumage involves body feathers but not wing flight feathers. It starts in January on wintering grounds and gradually proceeds through March or April. Moult occurs later the farther north you go in their range.
Red-throated Loons- Moults from winter to summer plumage partial and includes head, neck, body and tail feathers but not wing flight feathers. Moults occurs March-May. Summer plumage worn April-October.
Horned Grebe- Moults from winter to summer plumage partial and includes head, neck, breast, belly, flanks and some feathers of upperparts and some coverts in wing. Moults occurs March-April or later in NA.
Thank you very much for all the information John! I wound getting my membership to the AOU that I had meaning to get for a while now - it has been too long since I've read the Auk. Fortunately that also grants me access to the BNA project, although it took a while to process. The timing charts on the BNA site are fantastic!
If I understand correctly then, it seems that loons have a single 'catastrophic' moult when they go from Alternate to Basic plumage and lose all flight feathers simultaneously (losing the ability to fly), but the Basic to Alternate moult only includes body feathers. In any case, I may still make a trip to try and catch the loons on the last few days on their winter grounds down here.
Thank you again, and I'm going to head over to the BNA site to read the Brown Noddy description
Molt timing question - Loons and Grebes
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