Image copyright AFP Image caption Over the past decade some avian species, like ostriches, have lengthened their necks
The length of a bird’s neck is apparently linked to its body shape, according to new research.
Longer necks link to smaller, healthier gizzard sheaths – inner layers of tough fat – in the birds, say scientists.
The findings could be important to understanding how climate change is affecting the life cycle of many birds and other animals.
The research appears in the journal Current Biology.
Long necks have long been the subject of scientific interest.
For decades scientists have debated whether having a more “bellicose” neck could increase a bird’s life expectancy.
Now, in the new study, researchers from the University of Iowa and the Massachusetts Institute of Technology (MIT) have found evidence to support that conclusion.
This may help scientists better understand the impact of climate change on wildlife, said lead author of the study, Steve Bonnett.
“If we look at the whole body of work we can link a lot of the same things in many different species,” he said.
“So when you see trends like that, you can look at any population or say, ‘Here’s this bird, this bird is doing this, here’s this bird is doing that. It might not have any direct relationship, but it has to do with the body and weight.’”
The study was based on almost 10,000 observations made by 166 bird watchers over six years.
Image copyright NASA Image caption Back in 2013, a famous white-tailed eagle, known as the starling bird, made waves by setting off on a 2,000km flight
Biologists have traditionally worked on theories about what behaviours birds communicate, how they migrate and even how they breed and with which characteristics they are most likely to learn new strategies or intelligence.
The study involved compiling observations of specific physical characteristics of nearly 600 birds, made at bird reserve sites in south-west France and central England.
Scientists confirmed that some birds typically have longer neck but only in isolated populations where migratory pressures make it the order of the day.
In other places, the birds that were more likely to have a longer neck were also more likely to develop Gizzard sheaths, said co-author of the study Claire Crewe.
“It’s really taking into account if you have a certain propensity in a population to have a different variety of Gizzard sheaths,” she said.
“That has these strong associations to longevity and species persistence.”
Image copyright Getty Images Image caption As ocean levels rise, sea levels retreat and new ice sheets are formed, ice birds, such as the penguin, have found themselves living in previously frozen conditions
Gizzles sheaths are resistant to freezing and thawing, allow birds to forage longer and have a lower metabolic rate than other animals, like fish.
In many cases, this could have enhanced a bird’s ability to survive cold temperatures, said Dr Bonnett.
He believes that longer necks may be less common in birds with more diverse body types.
It’s impossible to know exactly how climate change may impact individual birds but “we could do something about climate change”, he suggested.
“If we can understand the body and nutritional compositions of birds, we can decide the limits of what’s safe for it to live.”
First known bird