It’s 5 O’Clock Somewhere

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Written by Pam Garrettson
Tuesday, May 24, 2011

Pam Garrettson.I didn’t change the time on my watch when I got here, which is how I found myself up at 4 a.m. one day, thinking it was 5—which it was—on the East Coast. OK, that wasn’t smart, but on the areas that the US and Canadian ground crews survey, keeping track of time can be complex. We are nearing the end of the survey, working out of Bismarck, ND. It’s on Central Time, but just across the Missouri River it’s an hour earlier, same as Montana and the "west river" portion of South Dakota. Daylight savings time is another complication, especially in Canada. Saskatchewan doesn’t switch to daylight time; so it’s always Central Standard Time (CST) there. During the winter, that’s the same time as Manitoba, but right now, the same as Alberta or Montana, currently on Mountain Daylight Time (MDT). Unless you are in Lloydminster (SK), which does switch, and honestly, I don’t know what time it is there.

Time zones came into use with the advent of railroads and the need to keep predictable schedules. Likewise, scientists often record times and dates in special ways to make data collection and analysis easier and more consistent. Recording time in 24-hour format makes calculations simpler. For the same reason, days may be expressed as Julian dates, such that each is numbered progressively from 1 to 365. So January 1st is 1, and July 1st is 182, except during a leap year, when it is 183. Got that? Me neither, so most biologists record date more conventionally in the field, then convert it later for analysis. But be careful. To stay on the same page with cross-border colleagues, make sure you write out the name of the month, as our numeric date conventions differ. In the US, 5/6/2011 is May 6th; in Canada, it’s June 5th.

Ducks have no such worries, yet they too keep daily and seasonal schedules. In temperate climates, timing of seasonal events is influenced by weather, habitat conditions, day length, and the characteristics of the bird. Nesting dates vary by species; here, mallards and pintails are the earliest dabblers to nest, followed by shovelers, blue-winged teal, and finally, gadwalls. Among divers, canvasbacks and redheads nest far earlier than ruddy ducks, which really don’t get going until June. Within species, we know that older females tend to nest earlier than younger females, and that earlier nesters tend to be more successful. Older females are also more likely to re-nest if they lose an earlier one, and in general, ducks are more likely to re-nest when water conditions are good.

The daily schedule for a breeding female and her mate depends largely on how far along her nest is. When laying begins, ducks visit nests relatively early in the morning, lay the egg (nearly always one per day), and leave after a short time. With each successive egg, she spends more time on the nest, but typically leaves by noon. Once the last egg has been laid, time spent incubating increases dramatically; typically the female attends the nest all night and most of the day, with short incubation breaks in the afternoon. Meanwhile, the male loafs on a nearby pond. During laying (typically between 7-13 days) and early incubation, the male will rejoin the female once she leaves the nest. Copulation between the pair continues through the laying period. In addition, he guards her against forced extra-pair copulation attempts by other males. Both strategies are efforts to ensure his paternity. Later in incubation, the male typically abandons the female, perhaps to find some action elsewhere, but if she loses that nest, he may return and pair with her again.

Twelve eggs is a good clutch size for this species, and the nest was about 1/3 of the way into incubation.

Twelve eggs is a good clutch size for this species, and the nest was about 1/3 of the way into incubation. Photo by Dan Collins, US FWS

An American bittern.

An American bittern. Photo by Dan Collins, US FWS