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by Dave Grant  Nesting herons in Florida Wading bird populations in south Florida have a history of fluctuation that not only rivals the stock market in its extremes, but exhibits trends that are usually the inverse of our economic expansions and contractions. At the end of the last century, bird populations plummeted because of the trade in their plumage for extravagant fashions. With protection, they rebounded to perhaps 2.5 million birds in the 1930's, a dark period for the economy. Today, with Florida experiencing some of the fastest growth in its history, bird populations are in deep trouble. By the mid-1970's populations dropped to 250,000 and today may be down to less than five percent of their level in the 1930's. The causes of this dramatic decline are complex. The basic problem is what some ecologists refer to as T.M.F.P. (too many people) forcing too much growth in a delicate environment, too quickly. This might be easier to deal with if we had better ways to manage development - skills our society has yet to perfect. The ultimate solution is as complicated as the many factors that are affecting the birds. The birds' troubles began in 1926 after a major hurricane flooded much of central Florida. Farmers and homeowners living in these wetland areas pressured the government to begin "managing" the waters of the state; building dikes at Lake Okeechobee and the canals to drain the naturally flood-prone glades. Farmers converted the valuable 10-foot veneer of muck that is the soil here (which acts like a sponge for rainwater) into fields that today grow half the nation's sugar cane. The draining of these wet soils has encouraged devastating fires, contributed to subsidence and replaced indigenous wetland plants with less-desirable cattails and other flora. The introduction of invasive exotic plants has further upset the ecosystem and hurried the extinction of at least a dozen native species. Flood control measures further altered water levels, and excess nutrients and pollutants from farms and urban development continue to runoff into the remaining water systems. Compounding these human impacts, three of the last five years have been much drier than usual in south Florida, affecting breeding and food supplies for wading birds. Normally, wildlife can rebound from yearly fluctuations in weather and other environmental extremes. But with as much as three quarters of their original habitat here altered or destroyed, the buffer for birds and other animals is gone and today they are much more sensitive to change. The declines are not confined to the Everglades or to wading
birds. Along the coast, rookeries of pelicans and other birds
are threatened too. Some researchers cite the large increases
in boat and jet-ski traffic as possible culprits. Both can be
disruptive to the feeding and nesting activities of some birds.   Although the overall picture is grim, there are some bright spots around the state. Many people in Florida have recognized the problem and are devoting time and resources to more wildlife preservation. Also, the state still has a great assortment of wildlife, and much of it is managing to endure the impact of our activities and to adjust. One surprising pocket of wildness is a site we visit each year on the Society's annual trip to the Manasota Key area. We call it the Highway Heronry, for lack of a more exotic local name we could borrow from some nearby landmark (The nearest being a drive-in church, but Heavenly Heronry was voted down). It is located about a mile inland from the Gulf and near several busy intersections and shopping areas. Since it is sandwiched between county highway and private, it appears safe from development for the time being. The site is a two-acre pond ringed along the south shore by tall pines and a fringe of thicket shrubs on the north. Some birds nest in the thickets, but most choose a small wet island in the center that is only 20-yards from the shoreline. This is apparently a suitable buffer for the birds and at the same time provides an unobstructed view for birders. The island vegetation consists of Brazilian peppers (sometimes called Florida holly), an invader and serious pest in south Florida. We visit Florida in early December, but it wasn't until our second year that we saw nests here. Prior to that, the site was only a night roost, at least that early in the season. At sundown several hundred birds fly in from the surrounding areas to jostle for choice spots in a raucous, but entertaining spectacle that lasts about an hour. The main characters in this drama are great blue herons, and American and snowy egrets, which occupy the island shrubs. Cormorants and noisy anhingas, along with additional late-arriving herons and egrets, settle uneasily in the fringe of thickets at the ponds edge. Night herons, coots, gallinules, and pied-billed grebes mingle and feed in the shallow freshwater pond. It is a mass of green, algae-filled water that is eutrophic from the bird guano but sustains many fish and turtles. Most of the birds disperse early in the morning to feed in the surrounding countryside. The great blue herons remain closer to home and squabble under the pine trees over fallen twigs that they then deliver ceremoniously to their mates. We counted 20 nests on the tiny island and two more in less desirable mainland thicket sites this year. This is three times the number we saw last year, and the youngsters were about ten days older too.  This appears to be a secure location for these sensitive birds, and although susceptible to human intrusions, they seem to be left alone by their human neighbors. Under the pines where birds collect nesting materials, we found a stomach pellet containing the remains of a hatchling, and have seen great horned owls and red-tailed hawks in the area; but judging from the number of healthy nestlings, the loss from predators is not alarming. The "highway herons" seem to be thriving and breeding earlier than other birds in the region and this is likely related to food supply. They are fairly tame and some may be "welfare birds" that have learned to beg for handouts at peoples' back yards. This is a fairly common phenomenon in Florida but is not a good practice since the birds become dependent on it. This small colony of waders may be able to continue to flourish
in this little rookery and help maintain a stable population
of wading birds in this area. They seem to be ignoring the trend
in other parts of the state and demonstrate to us that when provided
with a minimum amount of space and privacy, even wary and excitable
birds like these can coexist with people. NOTE: A Society Advisory Council member, Grant is a naturalist who frequently leads Society trips. He took all the photos. The drawing is by Susan Draxler. Vol 19, No. 2: June 1990 |