Field Tracking Efforts

Monday, March 24, 2014 8:20 PM | Anonymous member (Administrator)


Wade Harrell, U.S. Whooping Crane Recovery Coordinator

Field Tracking Efforts
Thanks to Texas Parks and Wildlife for putting together this excellent video of the whooping crane tracking effort. See it here.

The trapping team completed this field season with 13 marked birds this winter. This is the last season of capture and marking of whooping cranes in Texas. Sixty-eight whooping cranes have been marked with GPS transmitters during the past four years. Currently, 28 of those birds are still being actively tracked.

The study was conducted by a partnership of researchers from multiple organizations using lightweight GPS devices to track individual whooping cranes of the Aransas –Wood Buffalo population.

Efforts focused on putting tracking devices on adult whooping cranes captured on Aransas National Wildlife Refuge NWR, where the birds winter on the Texas coast, and on chicks at Wood Buffalo National Park, the birds’ nesting grounds in Canada.

The GPS units are attached to a bird’s upper leg and record four to five locations every 24 hours, information that is uploaded to a satellite every two and half days. These data reveal migration routes, habitat use, nesting locations, and much more. Biologists in the United States and Canada will use results of this work to identify management and conservation priorities in both countries.

The research partnership is made up of governmental and non-profit partners that include the U.S. Geological Survey, U.S. Fish and Wildlife Service, Canadian Wildlife Service, Platte River Recovery Implementation Program, Crane Trust, Parks Canada, Gulf Coast Bird Observatory, and International Crane Foundation.

Whooping Cranes outside the primary survey area:
Long-term whooping crane followers likely remember that over the last couple of years many whooping cranes spent much of the winter outside of the primary survey area. This was likely due to a number of factors including overall population expansion and ongoing drought conditions.

This year was different. Biologists detected more whooping cranes in the primary survey area and documented fewer individuals outside the primary survey area. This geographic shift among years may be due to shifts in food resource availability. While it was still a relatively dry year, some timely rains this past summer and early fall may have contributed to greater food resource availability in area coastal marshes. This may indicate that whooping crane behavior is adaptable and individual birds are able to shift their habitat and food use in relation to local environmental conditions. It provides a continued hope that the whooping crane population is resilient in the face of fluctuating environmental conditions such as drought. Wintering in a variety of places across a broader geographic range reduces the risk that a single localized catastrophic event could cause extinction.

Between Texas Whooper Watch and the increasing number of birds marked with satellite transmitters via the tracking study, biologists are in a much better position to document geographic expansion of the wintering grounds. Conservation and restoration of high-quality whooping crane habitat in Texas needs to be emphasized in the future so the growing whooping crane population has places to forage and raise young successfully during the winter season. Protecting and conserving habitat that provides the resources the birds need on a broad, landscape-scale will help the population continue to grow and contend with ever changing conditions.

The tables below provide the best understanding of birds that were outside the primary survey areas during the mid-December survey period. Keep in mind some birds may have been missed. Also, we cannot ever be completely certain that individual birds did not move between these locations and to/from the primary survey area during the survey flights.

These are three different data sources that are used to document birds observed outside of the primary winter area during mid-December.

Table 1: Texas Whooper Watch
Birds documented outside of the survey area in mid-December via Texas Whooper Watch

General Area Adults    Chicks    Total    Notes:
Mad Island Area/Matagorda County 2 1 3 Observed several times in mid-December, including during the annual Christmas Bird Count.
Robertson County 1   1 Observed multiple times throughout December and into early January with sandhill cranes.
Total     4  

Table 2: Tracking Study
Birds documented outside of the survey area from Dec. 11th to Dec. 23rd via the tracking study

General Area Adults   Chicks   Total   Notes:
North Matagorda Island (secondary survey area) 1
1 Marked as a chick in Canada in 2011. Detected via aerial secondary survey as well (see Table 3).
Calhoun County 1   1 Moved outside primary survey area on Dec. 14, 2013. Reported as a pair, but unconfirmed. Marked as a chick in Canada 2012.
Total     2  

Table 3: U.S. Fish and Wildlife Service Survey
Birds documented in the whooping cranes’ secondary areas on Dec. 12th & Dec. 17th via aerial survey

General Area Adults   Chicks   Total   Notes:
North Matagorda Island (secondary survey area) 1   1 *same individual reported in Table 2*

* The data and results presented in this report are preliminary and subject to revision. This information is distributed solely for the purpose of providing the most recent information from aerial surveys. This information does not represent and should not be construed to represent any U.S. Fish and Wildlife Service determination or policy.  

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