Birds have evolved over millions of years to thrive in diverse habitats around the world. Their unique adaptations allow them to live in the most challenging of environments.
In the first of a series of features about bird adaptations, let’s look at some of the amazing features they’ve developed:
Birds’ main limb bones are hollow, with special struts inside to keep them strong.
This makes them light enough for flight but strong enough to deal with birds’ daily challenges, like the graceful little egret in the photo above.
And lightweight feathers and bills, rather than heavy jawbones, teeth and fur, make them even more well suited to flight.
Birds’ feathers are organized in distinct lines and patterns, each having its own designated term.
The elongated feathers mainly used for flight are primaries, while the shorter ones are known as secondaries. The small feathers that cover the bases of these flight feathers are known as coverts, while the ones that cover the birds’ body, keeping them warm, dry and streamlined, are known as contour feathers.
A curlew displaying its primary, secondary and contour feathers.
The power of flight
Wings are similar to human’s arms but they’ve been adapted for flying.
The upper part of the limb is mostly hidden and it’s short and thick to maximise power for each wing beat.
The bend in the middle of the wing is actually the equivalent of our human wrist, and the last joint of the wing is the equivalent of our hand, but with only one ‘digit’ – this holds the long feathers used for flying.
Bird wings adapt to the needs of each species.
Many migratory birds have longer and more pointed wings than non-migratory birds. This aerodynamic structure helps to reduce air resistance during flight but may make it more difficult for them to take off from the ground. This means, when they’re disturbed, they may waste lots of energy flying away.
Bar-tailed godwit taking off
The broad wings of large birds, like eagles and buzzards, provide lift and stability, so they can glide on rising currents of warm air, enabling them to survey vast territories for prey without spending energy on flapping. These adaptations have allowed birds to access resources and habitats that would be otherwise inaccessible.
Pumping up the power
To keep energy flowing to their flight muscles, birds need to move blood around their bodies extremely fast.
Their large, four-chambered hearts proportionately weigh about six times more than a human heart.
They need to beat this heart super fast to meet the tough demands of flight.
Did you know: a small bird’s heartbeat rises to more than 1,000 beats a minute when it’s on the wing?
Birds are adapted remarkably well retain their body heat in chilly weather. Feathers play a vital role in this process, as they can fluff out to create insulating pockets of warm air.
Birds often tuck their heads snugly within their feathers to preserve heat and shield themselves from the cold.
As temperatures drop, birds also accumulate fat under their skin, which acts as a valuable layer of insulation to keep them warm and energised during the colder months.
Sanderling staying warm on a Solent shore
While their featherless legs might be more vulnerable to the cold, birds have ingeniously evolved a unique circulation system in their legs to keep themselves warm.
The arteries, which carry warm blood from the heart, run alongside the veins carrying colder blood from the legs.
This clever design allows the warm arterial blood to heat up the cooler blood in the veins, so that the extremities remain comfortably warm even in the frostiest of conditions.
Every year, millions of birds undertake epic journeys, often spanning thousands of miles, to travel between summer breeding grounds and winter feeding areas. These migratory feats require impeccable navigation skills, a keen understanding of seasonal cues, and remarkable endurance.
For example the Solent’s dark-bellied brent geese return to our shores from Arctic Siberia, as do little sanderling, while black-tailed godwit fly in from Iceland. These migratory adaptations ensure the survival of many species by allowing them to exploit seasonal resources across vast distances.
Find out more about the migration stories of Solent’s coastal birds.