Wednesday, March 7, 2012

Roseate Spoonbills

Newborn roseate spoonbill chicks in Florida Bay

Numbers of roseate spoonbill nests in Florida Bay are slowly climbing as we explore new territories. It's encouraging to see them rebound after a slow and steady decline over the last 15 years. Islands that we never considered suitable for the pink birds are surprisingly hosting good-sized colonies and reshaping our ideas of their nesting and foraging habits. 

Chicks around the age of 12 days, known as Stage II, will spend another 20 days on the nest before making their first flights. 

We're finding a healthy variation of chicks at different stages, from hatchlings to fledglings, all across the Bay. This isn't out of the ordinary but it helps us see how these birds' nesting schedules are related to food availability. For example, in the northwestern section of the Bay where tides control water levels, spoonbills nested earlier in the season because they could find sufficient food as tides withdrew. When you boat eastward where wind and rainfall controls water levels, you find that spoonbills choose to nest later, waiting for the dry season to kick in. Once water levels are low enough to amass fish in large concentrations, adults will commit to laying a clutch. With shallow water bringing an abundant food source, adults will be able to sustain their young through the nesting season. That's the plan, at least.

A chick only a few days shy of fledging the nest lays motionless below its nest after a cold front in February. 

Recently a cold front pushed through south Florida and dumped rain for three straight days. What seems like a small event to us, a 4-inch rise in water levels effectively disables the spoonbills from accessing optimal foraging grounds. Immediately after, across the board, we witnessed an abandonment of nests and several chicks not far from fledging, washed up in the mangroves. While it's too early in the data set to directly connect the rain event to nest abandonment, we can't say it was entirely coincidence.

A Stage II chick, about 10 days old is found lifeless in the rain-soaked red mangrove prop roots

I can't tell you how heart-wrenching this is to see, how helpless they look, but it's the reality that these birds live with. Albeit disturbing, this is exactly the point Audubon is trying to drive home. Water levels determine everything in the southern Everglades and Florida Bay. While we can't control the weather, we are controlling the water flowing from the north and we must be extremely careful with how we use it

1 comment:

  1. I suppose something will find it and then eat it. The circle of life.