Monday, September 1, 2014

Our resident cranes are back

A pair of sandhill cranes has returned to our lake. The tall, redheaded birds arrive at dusk to spend the night on a tiny wisp of weedy land surrounded by water.

Flying in to spend the night on an isle in our lake

Shortly after daybreak, they busy themselves with a bit of preening and stretching before flying off to destinations unknown. Although the birds never stay all day on our property, they stop by occasionally to probe the soil with their sharp beaks in search of seeds, bugs, berries or lizards. Inevitably, they leave, returning to the tiny island only when some inner clock tells them it's time to roost.

Sandhill crane morning rituals include extensive preening and stretches

Our lake has been a way station for sandhill cranes ever since a mated pair built a nest on a small island that appeared in the middle of the lake in 2001. Sandhill cranes like to raise their young on protected places such as small land masses surrounded by water or wetlands. We had a period of extreme drought 13 years ago and although lake levels have fluctuated widely since then, the cranes' commitment to our property hasn't wavered.

Unusually low water levels in 2001 exposed a long island of peat in the middle of our lake.  That year a sandhill crane couple nested on the island and hatched out two babies. 

Most years, a pair nests on one of the tiny isles in the north end of the lake and succeeds at raising one or two babies. There have been seasons, however, when the birds didn't reproduce at all or their young failed to survive.

During the especially wet spring of April 2011, the sandhill cranes abandoned a nest with 2 eggs in it when water levels rose and flooded them

As a group, sandhill cranes are doing well with about 500,000 birds worldwide divided into six subspecies. Three of those subspecies, the Greater, Lesser and Canadian sandhill crane, are migratory birds while the other three, the Mississippi, Cuban and Florida sandhill cranes, live their entire lives in limited regions. The migratory populations — cranes that nest in the northern climates and fly south for winter — are either stable or increasing, but the outlook isn't as bright for the non-migratory birds. Mississippi and Cuban sandhill crane populations are dwindling with both subspecies listed as endangered. The Florida sandhill crane population is doing a bit better even though it consists of only about 5,000 birds. The Florida Game and Freshwater Fish Commission lists the Florida sandhill crane (Grus canadensis pratensis) as threatened.

Large flocks of migratory sandhill cranes come to Florida in the winter

Because I see them in summer when migratory cranes have returned to their northern homes, the pair that spends the night on our lake is among that small group of year-round residents.  I suspect they are the same pair that we've been seeing for years.

Our resident crane couple with their most recent offspring

One of many interesting behaviors is their tendency to return year after year to the same nesting place. The cranes, which can live up to 20 years in the wild, are monogamous birds with both parents participating in the care of their offspring. Young cranes are called colts. A sandhill crane nest usually includes one or two eggs that hatch after about a month. Occasionally, both baby birds will grow to maturity but often only one bird survives.

Baby cranes that do live stay with their parents for about nine months before leaving to join a flock of other juvenile birds. These gatherings of immature, non-breeding cranes provide the young birds with opportunity to find mates and engage in courting rituals that include extravagant dancing behaviors. (Click below to see movie of mating dance.) Once mates have been selected, partners often stay together for several years before the successfully raising babies.

Like many Floridians, I find our resident sandhill cranes fascinating. These large birds are not only beautiful, but also surprisingly tolerant of humans. They often forage for food in our lawns and rest in the shade of our trees. Yet, because we see them so frequently, it's easy to take our resident sandhill cranes for granted.

The sandhill cranes foraging through our front yard in 2012

Although I often wish the sandhill cranes that spend the night on our lake would spend the day on our property, too, with a population of less than 5,000 birds, I try to be grateful that they come at all.

Please visit my YouTube channel to see several more videos of our resident sandhill cranes and their babies.

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