Aug 22 2017

Birds’ Beaks Are Air Conditioners

Published by at 7:15 am under Bird Anatomy

Song sparrow singing (photo by Peter Bell)

Song sparrow singing (photo by Peter Bell)

How do birds cope with heat?  They have several obvious ways and at least one we can't see.

Like us, birds stand in the shade and bathe to cool off.  They also appear to pant -- actually gular fluttering -- but their hidden cooling method is a surprise. They use the nasal conchae (pronounced KONK eye) inside their beaks.

Nasal conchae are complex structures that moderate the temperature of inhaled air and reclaim water from exhaled air.  Birds that live in hot dry places would benefit from bigger, better conchae.

A study published in The Auk: Ornithological Advances in 2016 found just that.

Raymond Danner of UNC Wilmington and his colleagues used CT scans to display the internal beak structures of two subspecies of song sparrows. The specimens were collected in Delaware and Washington, DC.

Delaware and D.C. don't seem to have different climates, but a bird of the dunes copes with a hot dry micro-climate compared to one that nests in a wooded inland park.

Indeed, as reported in Science Daily, the CT scans showed that "the conchae of the dune-dwelling sparrows had a larger surface area and were situated farther out in the bill than those of their inland relatives."

Here's a dune-dwelling song sparrow beak with elaborate air conditioning structures.

CT scan shows nasal conchae inside the bill of a Song Sparrow (photo credit: E. Gulson-Castillo and E. Sibbald via Science Daily)

CT scan shows nasal conchae inside the bill of a Song Sparrow (photo credit: E. Gulson-Castillo and E. Sibbald via Science Daily)

This extra internal gear means the dune-based song sparrows (Melospiza melodia atlantica) have larger beaks than their inland cousins.

I'll admit I haven't noticed the slightly larger beaks of the beach birds.  Have you?

 

(photo by Peter Bell)

2 responses so far

2 Responses to “Birds’ Beaks Are Air Conditioners”

  1. Susan Kingon 22 Aug 2017 at 12:47 pm

    The beach-dwelling song sparrow’s beaks were on average between 1-1.5 mm deeper and wider than the inland song sparrow’s beaks. A difference that small would be difficult to notice unless you had two birds (one of each subspecies) and a pair of calipers in hand. I wonder how these structures compare in subspecies that inhabit arid versus moist environments, and if these adaptations are present in other species that are found in both dune and inland environments as well?

  2. Kate St. Johnon 22 Aug 2017 at 1:53 pm

    Susan, yes a caliper!

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