Size, safety and parenting all have an impact on how quickly a species of bird matures, according to new research led by the University of Sheffield that could help scientists to understand and predict how animals will respond to climate breakdown and the destruction of habitats.

The team of scientists studied thousands of species of birds to understand why there is so much diversity in the length of time they take to grow from a fertilised egg to an independent adult.

The research, published in Nature Communications, is the most comprehensive study yet to consider the importance of lifestyle and environmental factors alongside evolutionary history and body size to explain the variation.

All organisms face a trade-off between reproducing and surviving and they solve this problem in different ways. The team found that bird species with a ‘live fast die young’ strategy develop quicker, allowing them to maximise the number of offspring they can produce in the short time they have available.

Findings showed that birds that breed and live in safer environments with fewer predators typically took longer to develop, possibly because they can afford to spend longer in a vulnerable state.

They also found that migratory birds develop much quicker, which may ensure they are ready to return to their winter habitats at the end of the summer.

As expected, the research showed that bigger birds took longer to develop – but even among birds of a similar size there was substantial variation in development times.

Professor Tamás Székely from the Milner Centre for Evolution at the University of Bath, a co-author in the study, said: “How long a chicken develops has fascinated biologists, ornithologists and poultry scientists for a long time.

“For instance, some songbirds complete incubation and brood care within 20 days, whereas albatrosses need to incubate the eggs and rear the young for up to a whopping 350 days.

“We conducted a large-scale study by comparing the duration of egg-incubation and chicks’ growth across more than 3000 bird species.

“We found that incubation length was pre-programmed and the embryo development inside the egg had similar rates across bird species.

“In contrast, post hatch development, i.e chick growth, was extremely variable between bird species, and it reflected their ecology: birds that breed in the tropics have slowly growing young that, in turn, require care by both the male and the female parents.”

Dr Alison Wright, co-author of the research from the University of Sheffield, said: “Our study on birds gives us some clues about the type of factors that may be important in other species. However, it may be that different factors are important for determining development length in other animal groups.

“The next step is therefore to address these questions using data that cover the breadth of the animal kingdom – from fish to mammals to insects – to gain an even broader insight into the factors shaping these fundamental differences across species.”

Dr Nicola Hemmings, co-senior author of the research from the University of Sheffield, said: “The insights from our research may prove crucial in understanding and even predicting how organisms may respond when conditions change, for instance as our climate warms and habitats become modified.”

Cooney et al (2020) “Ecology and allometry predict the evolution of avian developmental durations” is published in Nature Communications, DOI: 1038/s41467-020-16257-x.