Several people have expressed concern about low numbers of water birds on Lake Istokpoga this year, and about low numbers of wading bird nests the past several years. Whether bird numbers are lower than before is a rather hard thing to "prove," partly because we don’t have many detailed bird surveys. Keeping track of bird numbers might sound like something of importance only for bird watchers, but birds are an important indicator of the health of the Lake itself.

Scientist Mike McMillian of Archbold Biological Station has been doing studies on Ospreys around the Lake for years. He reports that autumn populations usually drop to about 50 birds, and around January, depending on the weather, the Ospreys start returning from their migratory wanderings (often in Central America) to start nesting. Last year’s total of about 250 nests around Istokpoga was very high and Mike expects a fairly good return this spring. Dr. Glen Woolfendon, also from Archbold, reports that they recorded about 14,000 lesser scaup (the white-backed diving ducks out in the middle of the Lake) on this year’s Christmas bird count. During the drawdown, FWC biologists report endangered Snail Kites nested on Lake Istokpoga in what appear to be the highest numbers on record. These numbers sound pretty good.

But many people note that there seem to be fewer coots, moorhens, inshore (dabbling) ducks, and wading birds than normal. Unfortunately, we don’t have a scientist following each of these birds and it is hard to tell what’s going on. My guess is that most of the changes probably are short-term effects related to the drawdown and hydrilla control. Plants help create habitat. Wetland plants drop seeds that wait until conditions are just right, sometimes waiting for decades, before they germinate. If you watch a shallow water area in consecutive years, this remarkable ability to wait allows "drier" condition plants to grow during drought years, and "wetter" condition plants to grow during wet years; the same spot will grow completely different plants in different years. During the drawdown and tussock removal project, heavy equipment removed material to help restore the natural sandy bottom. Along with the tussocks, seeds were removed as well. Rather than a diverse plant community, the first plant to grow in many areas was pickerelweed ("flag"). FWC subsequently sprayed this "weedy" species to allow time for more desirable plants to return. Hydrilla was controlled as well, and as vexing as hydrilla is for boating, many ducks and other birds like it. When more plants return, birds should too. Aquatic plant seeds are good at floating around and re-colonizing areas. My guess is by the end of 2002, many of our old friends: coots, moorhens, purple gallinules, ducks, wading birds, and others should be back in normal numbers.

As spring approaches, we wonder how wading bird nesting will be. Big Island and Bumblebee Islands have had large wading bird nesting colonies for years, and have made Lake Istokpoga one of the "Top 100 Wading Bird Colony" sites in Florida. When looking at the numbers of wading birds over the years, you will notice they are quite variable. Part of the variability arises because these breeding estimates are the records of only 1 to 3 counts per year. If the nesting season is earlier or later than average, the count day may not catch the rookery at its peak. Probably the largest source of variability is the climate itself. During extreme drought or flood years (El Nino winters can be very wet), wading birds may not find suitable conditions and either will forego nesting entirely, or move to another region to nest.

As mentioned above, wading birds were one of the most dramatic indicators of Everglade's problems. Similarly, wading bird declines were one of the important parameters that motivated Kissimmee River restoration, and their return is one of the restoration’s criterion for success. This group of birds are good environmental indicators because they tend to feed at the "top of the food chain." A proper chain of events is required to make fish abundant, or to make healthy snail, crawfish, worm,

tadpole, worm, or shrimp populations, and if that chain is not working, then wading bird populations often show the effects long before some biologist sifting through the mud will detect it.

My conclusion about birds on Lake Istokpoga right now is that they are doing fine. Of course we can’t be sure "how fine" they are, without long-term data sets. By next year we will be able to see in general if plants and most birds come back. For one set of "indicator" birds, wading birds, we can start a project to monitor their numbers. In the future, we can know their trends. Please call me if you are interested.

Table 1

Table 1. Approximate number of nesting pairs of wading birds in Lake Istokpoga (not including Cattle Egrets) a determined by 1-3 annual counts. Most abundant species are in parentheses.