Birds with short, stubby wings are less capable of relocating

A team of researchers led by Oregon State University (OSU) has found that tropical birds, which usually have shorter and rounder wings compared to their body length and shape, are less able to adapt to habitat fragmentation than the long-, slender-winged birds inhabiting temperate forests. To draw this conclusion, the experts analyzed the wings of over 1,000 bird species worldwide.

The research builds on a previous study from 2019 published in the journal Science which revealed that the nearer a species lives to the equator, the less efficient they are in adapting to current anthropogenic habitat fragmentation. 

Near the equator, animals evolved in environments that were not subject to massive habitat-altering events such as wildfires or storms. However, the reason behind tropical birds’ comparative lack of dispersal abilities has not been well understood.

What the researchers learned 

The current study provides strong evidence that forest birds in the lower altitudes – including the bare-faced ibis, the blue and gold macaw, the Malaysian rail babbler, and the green honeycreeper – are not good at relocating when their habitats are disrupted, since they were not required to evolve in ways that would make it easy to move to new areas.

“The new paper shows a strong latitudinal gradient in birds’ ability to disperse – i.e., move around to find a new place to live,” said co-author Matthew Betts, a professor of Landscape Ecology at OSU. “Birds toward the poles [such as woodpeckers, robins, jays, cardinals, owls, turkeys, hawks, and eagles] tend to be better movers, with longer, narrower wings that are better suited to long-distance flight.”

“It had been argued that species that don’t move much maybe tend to stay put just because they don’t care about losing pieces of their habitat or seeing it fragmented,” added Christopher Wolf, a postdoctoral researcher in Ecology and Conservation at OSU. 

“But we used a massive dataset that encompassed more than 1,000 birds globally to test whether birds with shorter, stubbier wings are more likely to be fragmentation sensitive, and whether this alone explains the latitudinal gradient we observed. In the end, there was strong support for the idea that birds that are good dispersers are less fragmentation sensitive,” he concluded.

The study is published in the journal Nature Ecology & Evolution. 

More about bird wings

Bird wings are fascinating structures that allow birds to fly and perform a variety of other activities. They are complex adaptations that evolved over millions of years, providing birds with the ability to navigate through the air in ways that other creatures cannot. Here are some interesting details about bird wings:

Anatomy

Bird wings are composed of feathers, bones, muscles, and connective tissues. The wing’s bone structure is similar to that of a human arm and hand, consisting of the humerus, radius, ulna, and a series of smaller bones analogous to fingers called the carpometacarpus and phalanges. These bones are very light and hollow, with a honeycomb-like internal structure that provides both strength and lightness.

Feathers

The feathers on a bird’s wing have a range of functions. The primary feathers at the end of the wing provide lift and are responsible for most of the propulsion during flight. The secondary feathers, which are closer to the body, help to provide lift and stability. Covering these are the smaller coverts which streamline the wing.

Types of Wings

Different bird species have different types of wings, which are adapted for their specific lifestyles. For instance, birds of prey like eagles and hawks have broad, long wings suitable for soaring and gliding. Swifts and swallows have long, slender wings for fast, agile flight. Penguins, although flightless in air, have strong, paddle-like wings adapted for efficient swimming underwater.

Flight Mechanics

During flight, a bird’s wing produces lift through its curved shape (airfoil), which causes air pressure to be lower on the top surface than on the bottom surface. By flapping their wings, birds create thrust that propels them forward. They control their direction, speed, and lift by changing the shape and orientation of their wings.

Non-flight Functions

Besides enabling flight, bird wings serve a variety of other functions. They can be used for display during courtship rituals, for balance while navigating on the ground, and for thermoregulation by adjusting the spread of their wings to control heat loss.

Molting

Birds periodically shed and regrow their feathers, a process known as molting. This keeps their feathers in good condition for flight. Molting occurs in a specific pattern so the bird can still fly and function normally while the process is underway.

Not all bird wings are designed for flight. Some species, like the ostrich or kiwi, have wings but are flightless. Their wings have evolved for different purposes, such as balance, display, or, in the case of the penguin, efficient swimming.

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By Andrei Ionescu, Earth.com Staff Writer

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