Give males some credit too – how older male gray jays influence female nesting behaviour
Dr. Ryan Norris and his colleagues provide first evidence of the importance of male experience on the timing of breeding in female birds.
Female gray jays (Perisoreus Canadensis) can adjust their reproductive timing in response to variation in the environment through phenotypic plasticity (the ability of an individual to adjust behaviour in response to different environmental conditions).
Gray jays are year-round residents of the boreal forest and rely on cached food not only for survival over the winter but also for late-winter nesting. Despite the fact that jays begin building nests in sub-zero temperatures, earlier laying females produce more young and are more likely to have their juveniles survive to the following fall compared to later nesting females.
Norris and his team examined how specific environmental (i.e. temperature, habitat characteristics) and social factors (i.e. age of breeders) influenced the timing of breeding in gray jays.
They used a large dataset collected from a population of marked gray jays in Algonquin Park studied from 1978-2015 combined with historical temperature data from Environment Canada.
In line with previous studies on other bird species, they found that temperature mattered. Females tended to lay earlier in warmer years than cold years, potentially due to limitations in food.
However, they also showed that older and more experienced females laid earlier than younger females possibly due to development in reproductive investment strategies over time.
But most interesting, when females were mated with older males, they laid earlier regardless of colder temperatures or their own inexperience.
Male experience seems to play a significant role in buffering a female’s response to climatic variation.
The researchers postulated that males are able to do this because of the experience they gain with ageing. More experienced males could be better at nest building/site selection, foraging and parental investment.
There are often an unexpected, and complex factors that can drive phenotypic plasticity in the context of climate change and, in this case, experienced males deserve credit for the fundamental role they play in how females adjust their timing of breeding.