Recommendations arising from this study*

*Recommendations are the interpretation and opinions of the University of Florida scientists involved in this study and do not represent official recommendations of the Wood Stork Recovery Team, U.S. Fish and Wildlife Service, or any other entity.

1. In addition to long-lived colonies obviously having characteristics that are regularly suitable for nesting, longevity by itself appears to result in a greater tendency for storks to return to the colony in the future, all other things being equal. This effect was strong and consistent in our analyses, and probably constitutes an important biological process. Management and conservation priority should be accorded to long-lived colonies, particularly those in existence for over 10 years. Our analyses suggest that the effect of longevity increases rapidly through at least 10 years of age, with a weak inflection point after about 15 years, and leveling off after about 20 years. Those years do not have to be contiguous, but a pattern of regular use and recolonization should be evident for a colony to be high ranking in this category. Large colonies should also be accorded higher management and conservation status because large colonies were more persistent than small ones, and were more likely to absorb nearby smaller colonies. Our studies do not suggest a hard threshold for size of persistent colonies, but there did appear to be a leveling off of the effect after 300 - 500 pairs.

2. Colonies on true islands that are separated from the mainland by a clearly perceptible body of water should rank highly as deserving of conservation and management attention. All analyses supported the idea that islands were preferred and resulted in greater persistence. We recommend a targeted analysis to identify appropriate existing island habitat, particularly in areas of higher stork colony density, to determine whether islands are a critical limiting resource for the stork population in the southeastern United States. To be appropriate habitat, islands would need to support large trees and shrubs, be within the mean plus or minus one standard deviation of the mean areal size of colonies, and not be regularly visited by humans.

3. We found a strong relationship between proximity of human structures and colony persistence. While this suggests that storks at minimum are not extremely sensitive to human disturbance, it does not suggest that current guidelines for disturbance near colonies should be changed. Our closest categories for human activity near colonies (100 meters) were no less than those currently recommended as approach distances. More importantly, we have two competing explanations for the apparent relationship - one suggests that storks might be benefitting from human proximity; the other suggests that storks are forced to nest near people because of a strong overlap in human and stork resource needs. In the latter scenario, storks could be negatively affected by human activities, but left without a choice for nesting sites because of resource needs. We also remind readers that the information on human proximity was gathered only recently (2010), leaving open the possibility that humans have simply encroached on stork nesting habitat, rather than storks preferring to nest near humans. We recommend studies to further examine the mechanisms involved in this association.

4. Relationships between land use change and stork colony size, longevity, extinction and colonization were relatively weak, and our analysis of these relationships was likely to have been compromised by the very short time span of land use change information available. We suggest that readers do NOT use the results of this study to prioritize or manage stork colonies based on land use change characteristics.

5. We recommend further studies on the effects of local hydrology on colony suitability. This study was not able to address this question well because of limited hydrological data, but this question remains as an important one for management and conservation. While local hydrology is not usually controllable, understanding the nature of effects (especially for areas outside of south Florida) may allow the identification of areas that are prone to poor or good hydrology. This is of special importance since hydrological/rainfall relationships and hydrological/human use relationships are likely to be strongly influenced by ongoing and future effects of global climate change.