This Category 3 hurricane was the first major tropical cyclone to hit the Southwest Coast of Florida since Donna in 1960. Having sat out these two severe storms in Naples, I can honestly say that they were quite different -- both created considerable damage to structures and vegetation. In this document I do not intend to comment about the affects of Wilma on the area other than to address what has or has not happened to the coastal waterbirds that we (my wife Ginnie and I) have studied for the last 32 years. After an event like this several questions about birds are common: What happens to the birds, were birds forewarned and able to adjust, and how did the birds deal with the storm? The following tries to address these questions.
Having such a large database for coastal waterbirds taken over a long period of time, allows for an in-depth analysis of specific events not only both before and after but also comparison to normal conditions to determine how and if the birds were affected. Unlike the birds, humans had advance warning of the hurricane and therefore we were able to census several areas before and after, to try and determine the immediate results. Even with such disruption to the coast, regular field work was conducted and a number of additional censuses of Sand Dollar Spit and Naples Beach were added. A number of colony/roosts (Rookery Bay, ABC Islands, Henry Key) were examined to determine the amount of damage and bird mortality. The coast was also inspected and photographed from Gordon Pass to Lostmans River (85 km., 53 miles) both by boat and small airplane. The following comments are derived from the above.
The most pronounced effect observed was the destruction to the coastal vegetation especially mangroves. Much of the mangrove has turned brown, many of the small islands have suffered extensive damage with both uprooted trees and a lot of broken braches that made the bird islands almost impenetrable. It was possible to work through the colony/roosts and look for dead birds and this is where most of the initial effects of Wilma on coastal birds were noted. In all 418 dead birds were recorded; ABC Islands 99, Henry Key 95, Sand Dollar Spit 18.
Note: In an article in the Palm Beach Post 10/29/05 a local resident of Chokoloskee was quoted as saying that thousands of dead birds were observed along miles of the Chokoloskee Causeway. This prompted my wife and I to survey the 1.5 miles of causeway, we recorded 206 birds not thousands; this shows what is often a problem between trained and untrained observers.
All but
two of the birds recorded in the colony/roosts and along the causeway were
waders (herons, egrets and ibis) almost all were killed by either being
blown into or being crushed by vegetation (10 just off the causeway appeared
to have been killed by cars, most likely dazed and staggering around on
the road). There was no oblivious cause of death for the Sand Dollar birds
but this is a lot for one census (the average is three).
The censuses before and after the storm at both Sand Dollar and Naples Beach actually showed a small increase in the coastal waterbirds using the sites. A good but small example: Piping Plovers at Sand Dollar before Wilma 21 were recorded; two days after 30 were recorded; on both of these censuses the same color-banded individual was observed indicating that this bird made it. Conversely the regular censuses right after the hurricane at the colony/roosts showed a slight decline in the waders coming in at sundown. In a way this is surprising as these patterns are what occur in a normal year and apparently the storm did not immediately alter normal seasonal trends. In October-November many winter residents are arriving into the area, this did not change which was demonstrated on the beaches and sandbars; thus the increase in some of the birds (shorebirds, gulls and terns). The waders using the colony/roosts peak in late August and then slowly decline until the next year; this accounts for the slight continuing down turn.
To answer the three questions from the first paragraph (noting that the answers apply to this storm and the immediate effects):
The above relates what apparently happened to the coastal waterbirds at least in the near term. That less than one percent of the birds in the area were killed and comparison to the long term data has not shown any effects on their numbers; it appears that hurricane Wilma had little effect on the overall population of coastal waterbirds. It should be noted that although we recorded 418 dead birds most likely many more also died but were not found.
All of the evidence indicates that, at least coastal waterbirds have no idea that a hurricane (or bad weather) is coming. Often before approaching storm, birds can be observed going about their normal actives as they were for Wilma.
There is some information as to what birds do in really bad weather, but not a lot. One example; there are some reports that right after the peak of a hurricane, small land birds appear at feeders. At our house we have a feeder in-between the house and a dense Fishtail Palm, during the storm sparrows, Cardinals and Blue Jays sheltered in the palm and were out on the feeder before Wilma's winds dropped to 40 mph. and the doves were feeding on the ground at the same time. It is safe to assume that the majority of land birds take shelter in heavy vegetation of some sort. For beach and sandbar birds there is little direct evidence but very few dead ones were found; it would be logical to suppose that they find cover in the lee of something nearby (debris, plants, small depressions in the sand, sand dunes etc.). Unfortunately one cannot be out there to document it. Walking through the colony/roost islands told the story: the waders had gone to roost at sundown as usual. Wilma hit in the early morning before first light catching the birds roosting; trees up-rooted, branches broke and a few of the birds were caught in the falling wreckage and killed. This is what was found both north and south of Marco Island. The species most affected were White Ibis (55% of the dead birds at the ABC islands) then Great Egrets (26% same location); it is easy to understand why the ibis as they are the most numerous species that roost at night throughout the year and for October are 73% of the total birds. But why were there so many Great Egrets when this bird is only 2% of the total birds spending the night in October?
The questions go on and on and on,. For instance, there were (and are) many more Brown Pelicans in the area than usual for October; only two dead pelicans were recorded (Chokoloskee Causeway). How in the world did they manage? In the weeks following the storm large numbers of Great and Snowy Egrets (the most ever for November in 27 years) have been counted coming in at sundown at Rookery Bay. What is going on?
Wilma has shed some light on coastal waterbirds and hurricanes, but like most things in the natural world, more questions are generated than answers.
