Summary of Florida Release Site Analysis

Notes from January 29 – 30, 2008 Meeting

In response to a catastrophic weather event that caused the loss of most of the 2006 class of ultralight-led whooping cranes, WCEP established a Winter Strategy Management Committee to explore options for an alternate winter release site. The analysis by the Winter Strategy Management Committee identified St. Marks NWR as the best alternative for another release site. To inform our decision on whether to use this alternate site, WCEP partners identified and prioritized our most important objectives for a winter release site. These objectives, which we used to compare the Chassahowitzka NWR and St. Marks NWR sites, are listed below along with a brief summary of how the two respective sites supported those objectives. As a group, we worked through these objectives at our winter meeting at Homosassa Springs State Park, January 29-30, 2008, to ensure that the Project Direction Team was fully informed on the assessments, concerns, and opinions of the WCEP field staff and other partners prior to making a decision during the subsequent Project Direction Team meeting.

Priority Objectives which were used to evaluate the proposed winter release sites:

1. Maximize winter survival of first-year cranes (reduce risks from weather events, predation, and lack of staff access to project site);

2. Maximize learning normal behaviors and survival in the wild (maximize learning safe roosting behavior, maximize conspecific association and pairing of wintering birds, maximize use of most suitable winter habitat returning birds)

3. Minimize exposure of project personnel to dangerous conditions
Secondary Objectives also considered were:

4. Minimize potential for cranes to learn tame/inappropriate behaviors

5. Maximize operational efficiency

OBJECTIVE 1: Maximize winter survival of first-year birds

Reduce risk from weather events: The risk from lightning was judged to be similar at each site; the risk from flooding was judged higher at Chassahowitzka. For both sites, we plan to implement measures to mitigate risk: Cranes will not be kept in a top-netted pen during weather events; Gate to automatically open during high water events; Higher ground habitats to be incorporated into the St. Marks pen.

Reduce risk from predation: The risk from bobcat predation was judged to be higher at St. Marks. The risk from alligators was considered similar at both pen release sites, but possibly higher at the impoundments at St. Marks if older birds return in future winters. There is also a risk of hog impacts at St. Marks, but not at Chassahowitzka, mostly of damage to the pen. We plan to implement measures to mitigate risk, but unclear if measures implemented at St. Marks would reduce risk to Chassahowitzka levels.

Reduce risk of accidental shooting by hunters: Risk from accidental shooting by hunters is very low in both cases, though slightly higher at St. Marks because of land access. Both pen sites are within closure areas, where hunting would be prohibited.

Maximize site access for project staff under all conditions: St. Marks is more accessible under all conditions.
Reduce risk from disease: Not a main deciding factor because there is not a significant difference between the two sites on this factor. Both sites are tidally influenced marsh systems, though flushing of site by tides is better at Chassahowitzka.
Maximize access to needed resources (water, food) at pen site: Supplemental forage, blue crabs, snails, fiddler crabs are available at both sites. Possibly more forage available at St. Marks if cranes use the coastal marshes but not a significant difference between sites because needed resources would be provided at both sites.

Minimize exposure to powerlines: No significant difference between sites

Minimize exposure to bioaccumulating toxins: No significant difference between sites

OBJECTIVE 2: Maximize learning normal behaviors and survival in wild

Maximize learning normal roosting: Similar, with some differences.

Facilitate appropriate habitat for cranes to learn predator avoidance behavior: The differences between the two sites were unclear - distance to treeline greater at St. Marks, more water for roosting at Chassahowitzka. Optimal roosting conditions were created at Chassahowitzka through the construction of an oyster bar and similar action is proposed for St. Marks. The qualities of each site were hard to characterize, and much debated; unresolved.

Maximize learning normal foraging behavior: Possibly more natural forage available at St. Marks. Because food is 95% crane chow provided at the pen site, under current protocols there is no significant difference between sites.

Maximize opportunities to socialize/bond with other whooping cranes: Fifty per cent of the current population has been wintering within 80 km of Chassahowitzka, and 60% within 100km. St. Marks is located along the Sandhill crane migration route into Florida and is 100 km northwest from the core of the existing wintering population. St. Marks is 50 km west of Hixtown Swamp and San Pedro Bay, known wintering locations. Will release at St. Marks affect the cranes’ ability to find each other to migrate together and find potential mates? Ultimate implications are unknown – initially fewer opportunities for pair formation on Wintering grounds by moving to new site.

Promote use of most suitable winter habitat in future years: A GIS analysis indicates 430,000 acres of crane habitat within 65 km of Chassahowitzka; 210,000 acres of crane habitat within 65 km of St. Marks. There is a possibility that cranes will use salt marsh habitat at St. Marks, but unknown. Currently, there is more preferred habitat available near Chassahowitzka. Central Florida is predicted to be one of the highest growth areas of Florida. Migratory birds can shift around and long term could respond to development by moving to suitable available habitat. The Big Bend Region (St. Marks area) is predicted to be one of the slowest growth areas of Florida, and may provide more suitable winter habitat in future years as current wintering sites around Chassahowitzka are developed.

OBJECTIVE 3: Minimize exposure of personnel to dangerous conditions

At Chassahowitzka, the pen is only accessible by boat, and during lower tides only by airboat; at St. Marks, staff can drive within visual distance of the pen. St. Marks offers greater staff safety during hazardous weather conditions.

OBJECTIVE 4: Minimize potential to learn tame/inappropriate behaviors

Minimize exposure to humans and public activity: Small differences but not significant. Both pen sites are on remote sections of the refuges.

Minimize exposure to tame, non migratory Sandhill cranes: No difference between sites.

Minimize exposure to costumed handlers: No significant difference between sites.

OBJECTIVE 5: Maximize operational efficiency

Increase efficiency of winter management staff monitoring older birds: The use of St. Marks would result in additional operational costs, as there will be a need for additional staff to manage the St. Marks release site.

Maintain level of access to veterinary care: Veterinary care for St. Marks would require either longer drives from existing contacts or establishment of new contacts closer to site. There is a concern for finding local vet contact for emergency response situations. Infrequent but important.

Staff access to pen site: Easier access to St. Marks by vehicle. Chassahowitzka is only accessible by boat and only by an airboat under low water conditions.

SUMMARY AND DECISION

The Chassahowitzka and St. Marks sites have different habitat characteristics and each meets many of WCEP’s priority objectives for winter management of the cranes. Primary drawbacks to the use of St. Marks include an increased risk of predation, less suitable habitat in the vicinity, potentially less opportunities for socialization, and increased project costs. Primary drawbacks at Chassahowitzka include higher risk of flooding, accessibility, and staff safety. While there were differences between the two sites in a number of the criteria that were used to inform our decision, the highest priority objective was judged to be avoiding the catastrophic loss of an entire cohort of whooping cranes.

The WCEP Project Direction Team made the decision to split the 2008 flock between the two potential winter release sites to eliminate the potential of a catastrophic loss of an entire cohort. Splitting the flock between Chassahowitzka and St. Marks meets the highest priority concerns for the safety and well-being of the young whooping cranes and offers an opportunity to learn more about what is best for these endangered birds. Evaluating the response of the cranes will improve WCEP’s understanding of whooping crane ecology and inform future management.

Wintering the young cranes at two separate sites in Florida will require greater effort and expense but will protect the tremendous investment of dollars and hope invested in these magnificent birds.

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