Old- Liviiif> Resoiinrs — Birds 



.fy 



(1980-92) tor the Atlantic. Mississippi, and 

 Central tlvways (Fig. 2). Production in the 

 Pacific Flyway exhibited a substantial decline 

 from 2.40 in 1 963-70. to 1 .7S in 1 97 1 -79. and to 

 1.60 in 1980-92. 



Likewise, survival would be lower during 

 1980-92 if population declines were caused by 

 declines in sur\ival. Comparisons of average 

 survival rates between 1980-92 and earlier peri- 

 ods were possible for only a limited number of 

 areas because few pintails were banded in many 

 regions. In the area encompassing northern 

 Alberta, northeastern British Columbia, and 

 southwestern Northwest Territories, average 

 survival during 1980-92 was higher than the 

 average for earlier periods for adult males (80% 

 versus 68%). young males (68% versus 53%). 

 and adult females (69% versus 64%). In south- 

 em Alberta, average survival during 1980-92 

 was higher than the average for earlier periods 

 for adult males (74% versus 70%) and young 

 females (86% versus 55%). Survival remained 

 constant between 1980-92 and earlier periods 

 for all age-classes of pintails banded in southern 

 Saskatchewan and southern Manitoba. In the 

 Dakotas. average survi\'al duiing 1980-92 was 

 higher for only adult males (77% versus 66%). 



These data reveal that possible declines in 

 pintail survival did not cause the population 

 declines observed during the 1980's. Overall, 

 survival was higher during 1980-92 than during 

 earlier periods for adult males that winter in the 

 Pacific. Central, and Mississippi flyways and 

 for young females that winter in the Pacific 

 Flyway. Survival remained constant between 

 time periods for adult females and young males 

 in the Pacific, Central, and Mississippi flyways. 



Given the small changes in production and 

 survival, pintail numbers should stabilize in the 

 Central and Mississippi flyways and possibly 

 the Atlantic Flyway. In the Pacific Flyway, how- 

 ever, the survival increases of young females 

 has not compensated for the overall decrease in 

 production. 



During the 1980's the Canadian prairies on 

 the average received less precipitation, resulting 

 in reduced availability of pintail breeding habi- 

 tat. Hopes for increased pintail population size 

 have been based, in part, on the expectation that 

 increased precipitation in the western Canadian 

 prairies would result in increased breeding habi- 

 tat and production. Female-based age-ratio data 

 suggest, though, that increased production is 

 unlikely to occur even with increased precipita- 

 tion because pintail production remained low 

 even when water was plentiful. Average age- 

 rafios for the Pacific Flyway when water in the 

 western Canadian prairies was above average 

 (total May ponds for southern Alberta and 



Mississippi 



Central 



Pacidc 



southern Saskatchewan exceeding 2.68 million) 

 steadily declined frotn 3.11 in the 196()"s. to 

 2.03 in the m7()'s. atid 1.86 in the 1980"s. 



Consequently, a fundamental change 

 appears to have occurred in pintail productivity 

 on western Canadian prairies, meaning that we 

 cannot base pintail management on the hope 

 that increased precipitation will result in a 

 return to the higher levels of production experi- 

 enced in the I960's. 



Researchers suspect that the production 

 decline may be related to the fact that the shal- 

 low-water breeding habitat favored by pintails 

 is most susceptible to agricultural drainage. By 

 1989. 78%' of the pothole margins (the transi- 

 tion zone where potholes meet farmland) and 

 22% of wet basins were degraded by agricultur- 

 al activity in prairie Canada (F.D. Caswell and 

 A. Didiuk, Canadian Wildlife Service, personal 

 communication). Increased intensification of 

 agricultine may also contribute to lower pro- 

 duction on the prairies through increased graz- 

 ing and cropping, increased nest destruction, 

 and increased use of agricultural chemicals 

 (Ducks Unlimited 1990). Further research on 

 the western Canadian prairies is necessary to 

 determine specific causes of production 

 declines in pintails and to determine methods to 

 increase production. 



References 



Ducivs Unlimited. 1990. Sprig: population recovery strategy 

 for ttie northern pintail. Ducks Unlimited. Inc.. Long 

 Grove. IL. 30 pp. 



Hestbeck. J.B. 1993. Overwinter distribution of northern 

 pintail populations in North America. Journal of Wildlife 

 Management 57:582-589. 



Johnson. D.H.. and J.W. Grier. 1988. Determinants of 

 breeding distributions of ducks. Wildlife Monograph 

 100. 37 pp. 



Smith. R.I. 1968. The social aspects of reproductive behav- 

 ior in the pintail. Auk 85:381-396. 



Smith. R.I. 1970. Response of pintail breeding populations 

 to drought. Journal of Wildlife Management 34:943-946. 



Fig. 2. Average production of pm- 

 tails in Atlantic. Mississippi. 

 Central, and Pacific flyways for 

 1963-70, 1971-79. and 1980-92 

 (Waterfowl Parts Collection 

 Survey. U.S. Fish and Wildlife 

 Service. Office of Migratory Bird 

 Management). 



For futher information: 



Jay B. Hestbeck 



National Biological Service 



Cooperative Fish and Wildlife 



Research Unit 



University of Massachusetts 



Amlierst. MA 01003 



