desertbirds wrote: A question for the softbill experts, What purpose do whiskers serve on some of the species here ? Inland thornbills. Hooded Robins ect.
Expert is such an ambiguous term but here goes!
The whiskers are a sensory organ to tell the bird the location of an insect in relation to its beak, that is, if the bug is off to the left the bird adjusts its head to centralise the bug for easy swallowing, many birds close their eyes, or the third eyelid comes over, when grabbing a bug to protect them from scratches etc.
Quote from the net.
Does that bird have whiskers?"
"Yes. It does."
"Why would a bird have whiskers?"
"I don't know. I've never seen a bird with whiskers before."
So went the banter between Gwen and Bobby Morgan of Seymour after Gwen discovered a small, mottled-brown, wren-sized bird on the ground beneath a Cades Cove picnic table. Bobby described the very conspicuous whiskers as about as long as the bird's bill.
The identity of the bird is a mystery, but many flycatchers have obvious whiskers. This bird was smaller and browner than an eastern phoebe - a common Great Smoky Mountains flycatcher.
Bird whiskers are called rictal bristles by ornithologists. "Rictal" refers to the rictus, the fleshy part of the bill near the back where the bristles or whiskers grow.
Bird whiskers differ from the stiff hairs near the mouths of mammals like cats and dogs. They are specialized feathers and not hairs. Each black or brown bristle is a stiff, bare, tapered feather shaft - a naked shaft without the colored, feathery parts that normally branch out from its sides. It's a modified feather that looks like a hair.
Flycatchers, swallows and some of the goatsuckers (especially whippoorwills) have conspicuous whiskers near their mouths. Because these species feed in a similar manner - by capturing flying insects in midair with their mouths - one might assume that whiskers have something to do with this feeding habit.
People used to think bird whiskers acted as a little net or funnel that increased a bird's "reach" beyond the diameter of its open mouth and helped guide more insects into the mouth.
However, one study of flycatchers with their whiskers experimentally removed showed that birds without whiskers caught just as many insects as birds with whiskers. Whiskers may keep insects (and airborne pieces of captured insects) away from the nostrils and eyes of birds that catch insects in flight. However, high-speed movies show some flycatchers snap up flies with the tip of the beak. Insects never reach the rear of the mouth, where they might come in contact with the whiskers.
Woodpeckers, crows and ravens have bristles around their nostrils. Take a close look at the brushy "moustache" on a downy woodpecker. A feather mustache helps a woodpecker avoid inhaling sawdust as it excavates trees for cavities and insects.
An ostrich has eyelashes - modified feather shafts around its eyes. Bristles on the faces of owls and harriers might act as organs of touch. Some owls see poorly up close.
Whiskers may serve primarily as sensory organs of touch for many birds.
This is a purpose of whiskers in mammals. Although these two different types of whiskers - hair and feather - developed independently of each other in mammals and birds, both may serve the same purpose, the sense of touch.
Birds surely benefit by having whiskers. Otherwise, they would not have them. Biologists are still trying to figure out the details of all the benefits of whiskers.
