Density‐dependent and phenological mismatch effects on growth and survival in lesser snow and Ross's goslings

Strong seasonality of high‐latitude environments imposes temporal constraints on forage availability and quality for keystone herbivores in terrestrial arctic ecosystems, including hyper‐abundant colonial geese. Changes in food quality due to intraspecific competition, or food availability relative to the breeding phenology of birds, may have consequences for growth and survival of young. We used long‐term data (1993‐2014) from the Karrak Lake nesting colony in the Canadian central arctic to study relative roles of density and phenological mismatch (i.e. days between seasonal peaks in vegetation quality and hatching) as drivers of annual variations in gosling survival among lesser snow (Anser caerulescens caerulescens) and Ross's geese (A. rossii). Survival of Ross's goslings was consistently higher compared to snow geese. For both species, annual gosling survival was greatest when phenological mismatch was minimal and when nesting population size was low. We also examined gosling struc...高纬度环境的强季节性对陆地北极生态系统中的关键植食动物（keystone herbivores）的饲草可获得性与质量（forage availability and quality）均施加了时间层面的限制。因种内竞争（intraspecific competition）导致的饲草质量变化，或相对于鸟类繁殖物候（breeding phenology）的饲草可获得性变化，可能会对幼雏的生长与存活产生影响。我们使用加拿大中部北极地区卡拉克湖（Karrak Lake）筑巢种群（nesting colony）1993年至2014年的长期监测数据，探讨了种群密度与物候错配（phenological mismatch）（即植被质量季节性峰值与雏鸟孵化期之间的天数差）作为驱动因子，对小雪雁（Anser caerulescens caerulescens）与罗斯鹅（A. rossii）雏鸟（gosling）年际存活率变化的相对作用。罗斯鹅雏鸟的存活率始终高于小雪雁。对于两个物种而言，当物候错配（phenological mismatch）程度最低且筑巢种群（nesting colony）规模较小时，雏鸟年存活率最高。我们还对雏鸟的结构展开了研究。