Bad Photos of Ugly Birds, Part IV

The breeding chronology of Bobolinks is well known. Bobolinks are polygynous. They are also single brooded. Nesting typically begins in mid- to late-May, and the first young fledge as early as late-June and early July, with additional young fledging into late-July and August. As the young fledge, freeing adults from much of their parental duties, adult Bobolinks begin a complete molt. It’s also at this time that adults of both sexes and young form pre-migration flocks. They begin to migrate shortly thereafter.

There are numerous late-summer and fall reports of Bobolinks massing in coastal marshes in the east, as well as in interior marshes. These accounts usually note that Bobolinks travel to such sites after breeding in order to molt. (For a list of sources about Bobolinks, some of which were used in this series of posts, please see Part III.)

Perhaps because there aren't any particularly large marshes or wetlands near the VOA or because of some other reason, Bobolinks at this site seem to complete or nearly complete their molt from alternate to basic plumage before departing, usually around mid- to late-August.

Migrating fall Bobolinks occasionally are reported in large numbers in nearby locales such as Miami-Whitewater Wetlands, a mixed wetland/prairie site in northwestern Hamilton County. In Ohio, there are historic and more recent records of migratory Bobolink flocks numbering in the hundreds, and more rarely thousands, in Lake Erie marshes as well as in grasslands and reclaimed strip mines in northeastern and central Ohio. I assume most of the birds are in basic plumage, since there don't seem to be any reports of large numbers of migratory Bobolinks still deep in their molt or arriving at these stop-over sites in alternate or near alternate plumage, which would indicate that molt was yet to start or perhaps suspended. Indeed, since Bobolinks usually undergo rapid loss of tail and wing feathers early in their molt, it's not likely that birds in such condition will purposely fly very far.

Since the birds at the VOA are usually well into their molts by mid- to late-July, I've assumed that the majority of them are molting on site, as opposed to making a "molt migration" to a non-breeding site such as a marsh or different grassland and beginning their molt there.

What I was never able to figure out at the VOA is how many, if any, migrating Bobolinks from other breeding sites drop into the VOA during their migration. I assume some birds outside of the VOA breeders find the site each summer.

To (finally) conclude this series of posts and their use of golden oldie photos, here is a gallery of sorts of molting Bobolinks. All photos were taken in the summer of 2004 at the VOA:

(Female. 11 July 2004)

(Female. 1 August 2004. This bird is just beginning its molt--almost a month after many of the males had begun their molt.)

(Female. New tail feathers coming in. 18 July 2004.)

(Two views of the same hatch-year bird in juvenal plumage. 3 July 2004.)

(Adult Bobolink, basic plumage. The fresh tail eathers have a softer or more rounded appearance compared to the "pointy-tipped" feathers of the hatch-year bird in the photo from the same date, below. 12 August 2004.)

(Probable hatch-year Bobolink. Points in favor: the tail feathers are more pointed than the adult in the photo above. The tertials are a little worn, too. The plumage seems "complete" with no noticeable gaps in flight feathers, coverts, tertials, etc. That is, there doesn't seem to be any clear sign that this bird is still molting, and by the date, and given that the other adult birds on site were mostly in complete or near-complete basic plumage, this should be a hatch-year bird. Where's a bander when you need one? Problem solved if the bird is in hand! 12 August 2004.)

(Adult Bobolink, sex unknown, possibly female given the early date? Coverts and wings showing signs of molt. Compare to Hatch-year Bobolink photos above and in Parts II and III. 11 July 2004)