Whooping Crane Survey Results: Winter 2019-2020


Whooping Crane Survey Results: Winter 2019–2020
506 Wild Whooping Cranes Estimated (95% CI = 342.6–678.0)

The U.S. Fish and Wildlife Service estimated the abundance of whooping cranes in the Aransas-Wood
Buffalo population for the winter of 2019–2020. Survey results indicated 506 whooping cranes (95% CI
= 342.6–678.0; CV = 0.168) inhabited the primary survey area (Figure 1). This estimate included at least
39 juveniles (95% CI = 26.4–52.3; CV = 0.170) and 192 adult pairs (95% CI = 131.2–262.7; CV = 0.171).
Recruitment of juveniles into the winter flock was 8.4 chicks (95% CI = 7.8–9.1; CV = 0.040) per 100
adults.


survey map 2019 Figure 1. The sampling area used to monitor whooping crane abundance on their wintering grounds along the Texas Coast of the Gulf of Mexico, USA.

During winter 2019–2020, the U.S. Fish and Wildlife Service continued to use a Quest Kodiak aircraft and surveys were conducted in late-January. The primary survey areas (approximately 153,950 acres; Figure 1) were surveyed once during January 27–28, 2020. The secondary survey areas (approximately 169,300 acres; Figure 1) were surveyed twice this winter during January 24–27, 2020. A concerted effort was made to survey the secondary areas this year since weather conditions precluded surveying them in winter 2018–2019 and only portions of them have been surveyed since winter 2015–2016.

The long-term growth rate in the whooping crane population has averaged 4.4% (n = 80; 95% CI = 1.85– 6.96%). The population remained stable from winter 2017–2018 to winter 2019–2020 (Table 1). The Canadian Wildlife Service reported 24 whooping crane chicks were fledged at Wood-Buffalo National Park in summer 2018 and 37 in summer 2019. Low fledge rates have resulted in reduced recruitment and no population growth since winter 2017–2018 (Figure 2).

Table 2. Whooping cranes documented outside of the primary survey area during January 23–28, 2020. 
 During the survey period, some whooping cranes were observed outside of the primary survey areas. Table 2 provides our best understanding of whooping cranes outside the primary survey areas during the survey period. Some birds may have been missed. It is impossible to be certain that individuals did not move between these locations and to/from the primary survey area during the survey period.

 

 
The survey protocol contains guidelines for promoting secondary survey areas into the primary survey area. This winter, we observed enough whooping crane groups in the Holiday Beach survey area to promote it to the primary survey area in winter 2020–2021. 

 

Table 1. Preliminary whooping crane abundance estimates for the Aransas-Wood Buffalo population on their wintering grounds, winter 2015–2016 through winter 2019–2020 (95% CI).
WHCR Abundance Table
Figure 2. Time-series of whooping crane abundance estimates and 95% confidence intervals for the Aransas-Wood Buffalo population beginning in winter 2015–2016. 
 

Table 2. Whooping cranes documented outside of the primary survey area during January 23–28, 2020. 

WHCR Outside Survey Area 

 

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. 

Matthew J. Butler, U.S. Fish and Wildlife Service, National Wildlife Refuge System, Division of Biological Services, P.O. Box 1306, Albuquerque, NM 87103, USA. 

Colt R. Sanspree, U.S. Fish and Wildlife Service, Aransas National Wildlife Refuge, 1 Wildlife Circle, Austwell, TX 77950, USA. 

Wade Harrell, U.S. Fish and Wildlife Service, Ecological Services, Aransas National Wildlife Refuge, 1 Wildlife Circle, Austwell, TX 77950, USA