Monday, May 31, 2010

A weekend at the rookery: Part 2

What strikes me most when I am in the Everglades occurs in rhythm. This relates to animal behavior which is largely dictated by one of two things at any given time, being the predator and the prey. It was nearly a full moon this weekend and the tides were strongly affected, which meant that the bait fish were being swept out of the backwaters. This meant that large predatory fishes such as sharks would be in the shallows collecting up bait fish. This also means that the birds have lots to eat. It seems the area of the rookery is full of activity in the water. On both mornings, the water was broiling, mullet jumping everywhere, schools of tiny bait fish sprinkling the water surface. The sharks were there too, coming right about along the edge of the mangrove islands. At one point, one came up on my boat from behind and made a violent wake in attempt to get away from it.

Above the water in the mangroves were the birds. Aside from the great whites and brown pelicans, snowy egrets were in number, but fewer than the others. I'd say a ratio of 1 to 10 snowy to great white. The snowys, being smaller are able to forage for sticks and food among the dark mangrove roots and mud. I could barely see their tiny nests hidden well and below the larger bird activity above. One of the nests was at eye level and I watched an adult come and go often bringing nesting sticks. The snowys were much more wary of me and I noticed they would fly wide around me. The egrets do that too but they seem to get use to me after a short while. The pelicans seem to mind me the least.

I recorded the rookery sounds with my voice recorder. I can now distinguish the noises a bit more. the baby pelicans sound like mooing cows. The snowys have the funniest noises, sounding like gurgles, or like someone trying to talk underwater. The baby egrets make a constant chirp and when the adult comes in with food, the sounds rise to loud crescendos. The pelicans do the same. It's an amazing sound and could probably drive certain people crazy. To me, the sounds are entertaining at the very least.

Like clockwork, a very large flock of juvenile ibises flew across the bay from the rookery area around 7 am. They appeared on both days at approximately the same time. I noticed this on Biscayne Bay as well. Seems they roost at night among the islands and then fly inland on a schedule, during the day for food. There must have been a hundred ibises and mostly juveniles. Very beautiful to watch as the sun rose above the landscape. I also noticed a flock of roseates near the same area I saw them a few weeks ago. This area of the bay is special and for some reason, it's prime avian real estate.

Lots of flying activity throughout the morning. Great whites and brown pelicans were in greatest number. the snowys were actively flying around as well. On the second morning, I noticed a small flock of cattle egrets. I wondered about these guys, where they are nesting or if they are nesting. I heard a green heron, but never saw it and interestingly, no osprey in this area. Although they are around the launch site area as usual.

As the morning grew hotter, more pelicans jumped into the water. One time, there were about 4 or 5 juveniles in the water and they seemed to be playing with each other. One would jab the other's behind, a pelican version of goosing. I watched one pick up a piece of oyster shell and fling it around a few times. They were learning and on occasion an adult would wander over to make sure the children were behaving.

The Wurdeman's heron that I found last time was there both days. I noticed at one point there was a very young bird in its nest, I was barely able to see the crown of its head. The heron stayed on the nest. I had staked out some distance away from the bird but occasionally I would take note of it. At about 9 am or so on both days, I saw a white egret come into the nest and then the Wurdeman heron would fly off to a distant island. Not sure what that was all about, but now that I think of it, I am wondering about the white bird that exchanged places with the Wurdeman. Had I been thinking straight, I should have noticed if it was a blue heron morph or a great white egret. Aren't great blue heron's and great white egrets two separate species? Surely they do not mate and isn't a Wurdeman a cross between a great blue morph and a normal version of it? Now I wish I had paid attention to the bird that flew into its nest.

I hope to get back here one more time. I wonder who will still be there by then? May be worth a visit to find out.

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