The Unison Call, – Newsletter of the North American Crane Working Group –
Vol. 27 No. 2, The Fall/Winter 2016-1
457 Whooping Crane Eggs Taken from Canada’s Nesting Grounds – Enough is Enough!
By Chester McConnell, Friends of the Wild Whoopers
An astonishing 457 whooping crane eggs were removed from nesting grounds in Canada’s Wood Buffalo National Park (WBNP) from 1964 to 1998 to be used in several experimental population projects and to establish (or augment) captive breeding programs. The eggs were taken from the only self-sustaining wild population of whooping cranes in the world, which is known as the Aransas-Wood Buffalo population (AWBP). The significance of such management decisions cannot be overemphasized. As of 2016, the AWBP numbers an estimated 329 birds. We can only imagine how much larger the AWBP would be today if the 457 eggs had not been removed. Certainly, not all of the eggs would have produced birds that would have survived and added to the population, but some would have.
Importantly, we need to recall why the eggs were removed. There was concern during the 1940s (and subsequently) that the AWBP could become extinct. Only 18 whooping cranes remained in that population in 1944-45. By 1967 there were just 9 nesting pairs. The U.S. Fish and Service (USFWS) and Canadian Wildlife Service (CWS) decided to make an attempt to help the species.
The two agencies made well-intentioned efforts, based on information at the time, to safeguard the AWBP, by establishing and then increasing the numbers and genetic diversity in the captive flocks used to produce eggs and, starting in 1975, by trying to establish new wild populations in new locations. Some of the repopulation attempts were failures, while others are still ongoing (with outcomes still unknown). Even so, there have been, and continues to be, serious differences of opinions about the various efforts and especially those involving taking whooping crane eggs from nests in WBNP.
Removal plans for whooping crane eggs
The egg removal plan involved taking one egg from nests with two eggs. (Technical information in this article is summarized from the International Recovery Plan for the whooping crane 2007, Appendix C, Egg Collection, pages C1 through C5.) The decision to collect one of two eggs from wild nests was made in 1965. Research personnel had learned that, although whooping cranes normally lay two eggs, only about 15% of families arriving on the Aransas National Wildlife Refuge (ANWR) wintering area have two chicks. Therefore, about 85% of nests usually contain one egg that is unlikely to result in a fledged chick. However, the second egg plays an unknown role in providing insurance that at least one chick survives. Habitat conditions, including water levels, food availability and predator abundance, affect survival. In years with suitable habitat conditions, crane pairs may raise two young. For example, during the 1958-59 winter, 8 of the 9 young that arrived at Aransas were from twin pairs. In 1997 and 1998, at least 9% of second-hatched whooping crane young survived to fledging age.
During the 61-year period from 1938 to 1998, there were 34 years in which no egg collection occurred at WBNP (mostly pre-1967). In those 34 years, 16 pairs of ‘twin’ juveniles arrived at ANWR in the fall. During the 27 years of egg collection at the nesting grounds, no pairs of twin juveniles arrived at ANWR in the fall (Cannon et al., 2001).
Brief history of whooping crane eggs taken
Eggs were first taken from 1967 to 1971 and in 1974 to further augment the Patuxent Wildlife Research Center (PWRC) captive population. More eggs were taken from 1975 through 1988 to provide 215 eggs for the Grays Lake cross-fostering experiment. Egg transfers to PWRC were resumed in 1982-1989 and 1991-1996, with 178 eggs being transferred. Fifty-eight eggs were transferred to the International Crane Foundation (ICF) beginning in 1990 and resumed in 1992-1996. Six eggs were shipped to the Calgary Zoo in 1994 and 1998, and a chick was transferred there from WBNP in 1999. Two eggs from an abandoned nest were picked up opportunistically in May 1998 and transferred to Calgary Zoo. Between 1967 and 1998, 244 eggs were taken from WBNP to the captive sites.
Effects on population growth rate
The effects of egg collection on the growth rate and overall fitness of the wild AWBP are unknown. There was, and remains, much disagreement among whooping crane professionals. Some contend that egg removals have not adversely affected the productivity of the wild population (e.g. Ellis and Gee, 2001). They point out that between 1967 and 1996, the era of egg pickups, the AWBP increased from 48 to 160, and the number of nesting pairs increased from 5 to 45. After reviewing and critiquing the several research findings, James Lewis, USFWS (retired biologist), in 2001, concluded that the data as presented did not support the views of Cannon et al. (2001) and determined that a re-analysis of the existing egg collection data was warranted (Lewis, 2001).
CWS biologist Brian Johns (retired) reviewed the data pair by pair and extracted as much information as possible from original reports and solicited the expertise of Dr. Mark Boyce, University of Alberta, for the analysis (Boyce et al., 2005). However, it’s been suggested that the data set used has biases, including: non-random nest selection; lack of a control group; not testing eggs for viability in the early years of collection; limited samples in certain years; and potential inaccuracies in chick surveys. Because of these issues, it is not possible to say what impact egg pickup has had on the size of the AWBP.
Some reintroduction programs benefited
The Whooping Crane International Recovery Team (IRT) recognizes that collection of eggs has benefited the whooping crane recovery program by providing stock to establish the captive flocks and providing offspring for release, thus increasing the total number of whooping cranes (cranes artificially reared and released into the wild) and helping to preserve the genetics of the species. The IRT in 2007 believed that data analyses to date did not indicate that egg collection would increase recruitment in the AWBP over the long term, but could increase recruitment in selected years.
In 2016, the IRT initiated a process to update the International Recovery Plan for the Whooping Crane, 2007 (IRP-2007). The goal is to incorporate new information and techniques, with the overall goal of down-listing and eventually fully recovering the species. A whooping crane population viability analysis (PVA) process is being used to produce information to be included in an upcoming version of the IRP.
The PVA would include whooping crane egg harvest on WBNP as one of several management scenarios that would be considered. According to Wade Harrell (USFWS) (personal communication), “That does not necessarily mean that we will harvest eggs from nests, only that we are considering it as we model a number of different management scenarios. If the PVA models indicate that it would provide significant benefit to the population, we would consider it further as we look at political, logistical and cost constraints of various management scenarios. So, to be clear, no decisions have been made.”
Friends of the Wild Whoopers (FOTWW) is opposed to any additional collection of wild whooping crane eggs from WBNP. Based on several unpublished communications, we believe that poor parenting skills of captive-reared whooping cranes and/or habitat quality is the reason for the serious problems in the Eastern Migratory Population. According to the genetic master plan, the genetic diversity of the AWBP is well represented in the three captive flocks, hence there would be little to be gained genetically in the captive flocks by removing additional eggs from WBNP at this time. Genetic experts have recommended that, as a minimum before any additional eggs are picked up from the wild, a large-scale genetic study is needed in WBNP, since information on the composition of nesting pairs has been lost with the cessation of color-banding in 1988 (IRP 2007). Frozen semen banks should be maintained to prevent loss of founder lines. A national serum bank should be set up to serve as a repository of genetic material for the species.
FOTWW is not critical of experimental projects preformed in the past including the Gray’s Lake cross-fostering experiment and the augmentation of the PWRC whooping cranes. Such early projects were learning experiences and measures to help save the species. Yet it is inexcusable to waste more eggs taken from nest of the only remaining population of self-sustaining whooping cranes to repeat past failures.
FOTWW believes all eggs should remain in the nest on WBNP because there is no convincing need to take more.
Boyce, MS, SR Lele, BW Johns (2005) Whooping crane recruitment enhanced by egg removal. Biological Conservation 126:395-401.
Canadian Wildlife Service and U.S. Fish and Wildlife Service. 2007. International recovery plan for the whooping crane. Ottawa: Recovery of Nationally Endangered Wildlife (RENEW), and U.S. Fish and Wildlife Service, Albuquerque, New Mexico. 162 pp. (pages 51-52)
Cannon, JR, BW Johns, TV Stehn (2001) Egg collection and recruitment of young of the year in the Aransas/Wood Buffalo population of whooping cranes. Proceedings North American Crane Workshop 8:11-16.
Ellis, DH, GF Gee (2001) Whooping crane egg management: options and consequences. Proceedings North American Crane Workshop 8:17-23.
Lewis, JC (2001) Increased egg conservation: is it essential for recovery of whooping cranes in the Aransas/Wood Buffalo population? Proceedings North American Crane Workshop 8:1-5
Chester McConnell, President of FOTWW wrote the above article. He has worked for whooping cranes for 20 years in several capacities. Most recently as FOTWW’s President he has visited military bases and Indian Reservations throughout the whooping crane migration corridor in 7 states. He advises the military and Reservation personnel about how to develop and manage “stopover habitat” for the cranes. He also writes detailed management plans for all sites he visits. He is now being recruited to provide the same services for other areas along the migration corridor. McConnell and Pam Bates are the co-founders of Friends of the Wild Whoopers. McConnell also served with Whooping Crane Conservation Association for 12 years. He served as WCCA’s President, Board member, webpage manager and editor of their news letter. McConnell also served as a wildlife biologist with Tennessee Wildlife Agency and as Wildlife Management Institute Representative for 31 years where he was involved with a variety of wildlife species and their habitats. He has a Masters of Science in Wildlife Biology.
1 thought on “457 Whooping Crane Eggs Taken from Canada’s Nesting Grounds”
thank you for all your work to save these magnificent birds!
Comments are closed.