Unexpected Look of the Ears of Crows

It’s nice to see this happy crow.

The footage below, posted by trained crow handler and animal volunteer Olly Peckar, shows a very happy crow getting some gentle pets while Olly exposes its ear from underneath its feathers.

Let’s just say we weren’t expecting something that… big?

happy-crow

Avian ears lack the external pinnae that our human ears have, but they do have an internal cochlea like us – only it’s not shaped like a spiral, it’s mostly straight.

Birds are known for their keen sense of hearing, and also their ability to figure out if a sound is coming from above, below, behind, or next to them.

Wherever the source is situated, somehow a bird is able to localise it, and all without an external ear structure like mammals have.

Scientists have only recently figured out how they do this, and it turns out that in lieu of an external ear, birds use their entire heads to detect the location of incoming sound waves.

“Because birds have no external ears, it has long been believed that they are unable to differentiate between sounds coming from different elevations,” Hans A. Schnyder from the Technische Universität München in Germany explained.

“But a female blackbird should be able to locate her chosen mate even if the source of the serenade is above her.”

Back in 2014, Schnyder and his team investigated the hearing ability of three bird species – crow, duck, and chicken.

They found that the birds were able to identify sounds from different elevation angles thanks to their slightly oval-shaped heads, which appear to process sound waves in a similar way to the external ears of mammals.

Turns out, birds receive different sounds at different volumes, and this helps them figure out the general direction of the source.

Sounds originating from the same side as the ear hit the eardrum at a certain frequency, but once they passed through the head and reached the eardrum on the other side, they would register at a different frequency.

“The eardrum differences allowed the bird’s brain to determine whether the sound was coming from above or below or at level with the bird,” CBC News explains. “That meant the bird’s head was able to reflect, absorb or diffract the sounds.”

Ability of Birds to “See” Magnetic Fields Helps Them Navigate

A unique protein in the eyes of birds may be what grants them their navigation abilities, according to new research. An interesting finding considering how it might be able to be replicated.

The mystery behind how birds navigate might finally be solved: it’s not the iron in their beaks providing a magnetic compass, but a newly discovered protein in their eyes that lets them “see” Earth’s magnetic fields.

These findings come courtesy of two new papers – one studying robins, the other zebra finches.

The fancy eye protein is called Cry4, and it’s part of a class of proteins called cryptochromes – photoreceptors sensitive to blue light, found in both plants and animals. These proteins play a role in regulating circadian rhythms.

There’s also been evidence in recent years that, in birds, the cryptochromes in their eyes are responsible for their ability to orient themselves by detecting magnetic fields, a sense called magnetoreception.

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bird-vision - Copy

According to researchers at the Theoretical and Computational Biophysics group at the University of Illinois at Urbana-Champaign, whose researcher Klaus Schulten first predicted magnetoreceptive cryptochromes in 1978, they could provide a magnetic field “filter” over the bird’s field of view – like in the picture above.

Older Forests Have Irreplaceable Value for Conservation, Study Finds

There’s been a lot of wildlife losses over the past several decades and a tenth of the wilderness has disappeared since the 1990s. This research on forests and birds is a reminder that that there’s still much that needs to be done to get human activities on a better track.

Old, complex tropical forests support a wider diversity of birds than second-growth forests and have irreplaceable value for conservation, according to an Oregon State University-led exhaustive analysis of bird diversity in the mountains of southern Costa Rica.

During their surveys, researchers found similar numbers of bird species in secondary stands compared to stands comprised entirely or in part of old-growth forest. However, the bird community in secondary forest was clearly shifted towards non-forest species, and only old-growth forest stands tended to include rare birds and to benefit biodiversity across the entire landscape. Scientists reported their results this week in the Journal of Applied Ecology.

The findings are important because in some cases, conservation programs have focused on the potential benefits of secondary forests. Although secondary forests do have value for conservation, the study suggests that primary forests are necessary as sources of biodiversity and as a refuge for species that can colonize other sites that are being restored. Thus, these results suggest that a strategy focussing only on second-growth forests may not benefit conservation-relevant species. Indeed, such stands tend to support only a few common species that can survive in highly disturbed areas.

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Effective conservation efforts should include maintenance of large old-growth forest tracts, the scientists wrote, and insure that human activities in the forest do not drive away species that depend on such areas. The results also suggest that restoring forests is likely to be most effective for forest birds if such efforts are performed in the vicinity of primary forest. This is likely because primary forest will provide a source for forest birds that may colonize the restored forest. Relying on secondary forests alone may create “potentially misleading expectations,” researchers wrote, that landscapes significantly modified by people can still accomplish conservation goals.