Richard Collins: Multi-tasking isn't just for humans
URI doctoral student Colby Slezak places a leg band and GPS transmitter on a female American woodcock at the Francis Carter Preserve in Charlestown, Rhode Island. Images courtesy of Colby Slezak
What is this life if, full of care, we have no time to stop and stare — 'Leisure' by William Henry Davies
Are women better multi-taskers than men?
A Chinese study found that they are, but a Swedish one found the opposite.
For birds, however, multi-tasking isn’t possible. A male, establishing a territory and securing a mate, must pull out all the stops. Females have to build nests, form eggs, incubate them, and rear chicks. ‘A woman’s work’, as they say, ‘is never done!’
Even when the brood has flown, the exhausted parents face challenges — they must replace their tattered worn-out feathers. They will need a pristine new set to get them through the winter. Stay-at-home birds will scrape out a precarious living at the mercy of the weather. Migrants lay on fat to fuel their dangerous, energy-demanding, journeys south. There are no free lunches for birds; it’s ‘all hands to the pumps’ throughout the year. Devoting all their attention to the activity in hand is essential.
Or is it?
It’s been suggested that there’s an exception to the rule. ‘Itinerant breeding’, where a bird interrupts its migration to nest en route, is suspected, although not proven, in about half a dozen species.
The American woodcock is a prime suspect: males engage in spectacular flight displays, known as ‘roding’, at locations along their migration routes. The cocks don’t stake out territories, so they must be trying to impress females. Why? Also, many females arrive at their nesting locations in the US and Canada late in the season. What delays them?
Colby Slezak, from the University of Rhode Island, fitted GPS tags to more than 200 female American woodcocks and tracked them. Monitoring the movements of individual birds on his computer, he found that females halt for extended periods during migration. When the locations of these stop-overs were checked out, the birds were found to be nesting. An itinerant female having fledged her brood, would continue her journey for a further 100 to 1,500km, and nest again.
This, it’s claimed, is the first conclusive demonstration of itinerant breeding. The behaviour has some advantages. Nesting becomes feasible earlier in the faster warming south and can be repeated, as conditions improve, further north. This effectively extends the breeding season and reduces the demands of long-distance migration. Also, birds can adjust their breeding strategy to cope with unexpected weather changes.
The woodcock’s way of life facilitates the practice. Like our Irish species, American ones are promiscuous and into casual sex. A male will perform his extraordinarily slow flight display, land near a receptive female, and mate. These cryptically camouflaged ground-nesting birds have eyes in the back of the head to spot approaching enemies. She lays relatively small eggs for her size, so that she will have the resources to nest repeatedly on her journey. The birds do not form long-term bonds, nor do potential fathers stick around.
For American Woodcocks, stops along spring migration routes aren’t just for rest. New research has found that these birds raise chicks at multiple points along their journey, a strategy that may make them more adaptable to a changing world. @gennaro_tommahttps://t.co/oRiCIK3M7j
— Audubon Society (@audubonsociety) April 25, 2024
Our Eurasian woodcocks, although larger, are close relatives of the American species. Migrants come to Ireland from Scandinavia and Russia, which raises an intriguing question? Do they also indulge in itinerant breeding along the way?
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