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Brood rearing has an immediate survival cost for female Chinese Grouse Tetrastes sewerzowi

Zhao, Jin-Ming, Fang, Yun, Lou, Ying-Qiang, Swenson, Jon E., Sun, Yue-Hua
Journal of ornithology 2018 v.159 no.4 pp. 1019-1029
conservation areas, life history, probability, nesting sites, Tetrastes sewerzowi, breeding, models, predators, adults, radio telemetry, demography, brood rearing, chicks, habitats, females, prediction, China
Reproductive activities can incur various costs to breeding individuals in birds. One cost is that reproduction decreases survival probabilities of attendant individuals, which may have a major effect on population demography. During brood rearing, adults of precocial species usually make extensive movements to lead their young to sites with adequate food resources and dense cover. However, few studies have evaluated the effects of brood movement on attendant precocial adults. In this study, we tracked female Chinese Grouse during brood-rearing periods using radiotelemetry at Lianhuashan Nature Reserve, Gansu, China, during 2010–2012, to evaluate the effects of brood rearing and movement distances on females’ survival probabilities using known fate models in program MARK. All 41 females attempted to breed, and 30 females successfully hatched at least one chick; 11 failed during the incubation period. Although females with broods moved more extensively than females without broods, movement distances did not influence survival probabilities of attendant females. Seven females with broods were killed by predators, resulting in a lower survival probability (0.958 ± 0.016 weekly survival and 0.679 ± 0.099 through the 9-weeks brood-rearing periods) than for females without broods, which all survived the brood-rearing periods. Our results agree with the prediction of life history theory, which assumes that cost must correlate with reproduction. The extensive movement patterns found in this study might reflect a lack of suitable brood-rearing habitat near nest sites, which might be detrimental to chick survival and influence the persistence of this population.