EEL FIRE MANAGEMENT MANUALPrepared by The Nature Conservancy |
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| Species with Special Considerations—Florida scrub-jay | ||||||
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development have led to an alarming loss and fragmentation of scrub ecosystems. Scrub losses since presettlement times range from 70 - 85%, with most of the losses occurring since 1950 [8]. Much of the remaining scrub has been severely degraded by suppressing the high-intensity fires that formerly swept the Florida landscape. As a result, many scrub landscapes are no longer self-sustaining. Loss and fragmentation of scrub ecosystems has severely reduced the size and distribution of the Florida scrub-jay population. Approximately 4,000 breeding pairs were present statewide in 1993, an estimated 23% decline from a decade earlier, and less than 10% of pre-settlement numbers. They have been extirpated from nine of the 39 counties in which they formerly occurred, and their existence in another six is precarious [9]. Recent work [9] has grouped remaining populations into twenty-one metapopulations, which are clusters of geographically isolated populations that are linked by sufficient dispersal to effectively unite them demographically. Today, only three metapopulations are considered large enough for long-term viability: Lake Wales Ridge, Merritt Island-SE Volusia, and Ocala National Forest. Two others, Martin and NE Lake, were classified as having low risk of quasi-extinction over a 60-year period. All but two of the rest were considered highly vulnerable to quasi-extinction within 60 years, although habitat acquisition could forestall that possibility in some. Florida scrub-jays were numerous and widely distributed in Brevard county in 1992-1993, the time of the statewide mapping project [9]. At that time the county contained three large (> 100 territories) and one small one. The Merritt Island -SE Volusia metapopulation ranked second in the state at 536 territories, the South Brevard-Indian River-North St Lucie ranked fourth at 158, and the North Brevard ranked eighth at 101. The Central Brevard metapopulation contained 36 territories. Subsequent studies [9] documented substantial declines within these metapopulations, with losses approaching 50% over a decade. Annual censuses of the large population on Cape Canaveral Air Force Station, a major component of the Merritt Island -SE Volusia metapopulation, document a 15% decline in number of groups and a 23% loss of birds over the last five years [4]. A successful management plan for Florida scrub-jays must do the following:
Most populations of Florida scrub-jays are small and geographically isolated. The probability of extirpation of such populations is high and the likelihood of recolonization low. Consequently, it is imperative that existing population be protected to minimize further losses. Recovery efforts need to be expedited to maintain and, where possible, expand the current size and distribution of existing populations. Among the greatest threats to the long-term persistence of Florida scrub-jays is lack of optimal habitat. All potential scrub habitat on protected lands, whatever its current state, should be returned to optimal condition. Prescribed fire will be the principal tool for scrub restoration. Fire frequencies should maximize the sustainable amount of optimal habitat for each property, which will be a function of vegetative response to fire. Soils, nutrients, water table, species composition, fire |
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