Sunday, December 22, 2013

A Female Juvenile Rufous in Union County, Tennessee

This juvenile female Rufous Hummingbird is currently wintering in the Sharp's Chapel area of Union County Tennessee at the home of Jim Turnblazer.  The habitat is open pasture land and grassland with shrubby edges, a very different habitat from the wooded suburban area selected by the Rufous female in the previous post.  
Female Rufous hummingbirds are more difficult to identify than males which have more rufous coloration in their feathers, even as immature birds. The wind was biting cold on the morning of December 15th while Mark Armstrong, Jane Kading and Jim Turnblazer worked together to set up the trap near the same area that this hummer was accustomed to finding the feeder.
That famous Rufous personality became evident as the hummingbird advanced to the area of the feeder, despite the activity, and hovered in the nearby shrub making a hard "tik, tik, tik" call. Mark has described this call as the sound he often hears when the hummer is in the vicinity and sometimes before it approaches the feeder.
This hummingbird was not deterred by the activity, and was soon captured in the trap, above.  The utility light hanging to the right helps to keep the sugar-water from freezing when temps drop below freezing.
Above Mark, gets his band ready while Jane holds the bird temporarily, and below he removes the hummer from the mesh bag.
The examination and banding of the bird is efficient and progresses quickly.  The band is placed on the right leg first and measurements are taken to help identify the species and document the bird.
Above the wing is measured with a digital instrument, and below the tail length is measured.  Each of these measurements help to confirm the species and sex. Females generally have longer wings.  Tail feather width and length can sometimes be the distinguishing characteristic between two very similar species.
Below, the beak is examined through two magnification aids to determine the amount of grooving.  The grooving in the beak helps to identify the age of the bird.  This young female had a number of grooves in her beak indicated that she had hatched in 2013 and is referred to by biologists as a "hatch year bird".
Mark uses a simple straw to blow belly feathers aside and examine the appearance of fat.  Both male and female hummingbirds have a bare patch on their bellies that is hidden by feathers, but only the female incubates young.  Examining this bare area for fat deposits helps to determine the general health of the bird and whether she is getting the nutrients she needs to sustain a good body weight.
The hummingbird was then weighed, below.  Her weight was found to be a normal weight for her species and age. Through-out this examination, Mark holds the bird in a small bag made from hosiery material.  The bag helps him control the bird, keeping her calm and reducing stress.
Examination of the tail feathers show the distinguishing rufous coloration that is found in the Selasphorus species of hummingbirds, which include the Allen's, the Rufous and the Broad-tailed species.  All of these species have been found wintering or migrating through Tennessee in past years.  
Below, you can see the variations of color in the back feathers of this individual, ranging from gray to lime green to aqua, even in the dull light on this overcast day.
Many of the juvenile feathers appear grayish as they gradually change from juvenile plumage to the brighter colors more characteristic of mature birds.  Her gorget feathers are still developing and the number of irredescent orange-red feathers on her throat may increase by the time she matures.  The number of gorget feathers varies with each individual female.  As with the male's gorget feathers, the iridescence in these feathers makes the color of the surface appear different with changes in the reflecting light.  
While we were warming our hands by the fire, we watched for the hummingbird's return to the feeder. A second feeder was provided near a window around the corner from the porch feeder and we enjoyed seeing her visit this feeder several times before we departed. Jim recently reported that she is still present and visits both feeders frequently.

Next:  Our third visit--a male Rufous in Loudon County

In east Tennessee, report hummingbird sightings to Mark Armstrong at or 865-748-2224. For a list of contact information for other eastern areas, visit winter reporting on the Hummer Study Group website or report sightings to Bob and Martha Sargent, or 205-681-2888.

Links and Resources:

Western Hummingbirds Wintering in Tennessee
Allen's Hummingbird in Tennessee
Rufous Hummer in Knoxville 
Other blog posts on Wintering hummingbirds in Tennessee
In recent years, fourteen species of hummingbirds have been documented in the east during fall and winter months.  Visit Bob Sargent's information on wintering hummingbirds
Bob Sargent describes the Rufous Hummingbird as very cold-hardy.
Sargent on wintering Calliopes and the Allen's Hummingbird
Hummingbird banding
Hummingbirds in watercolor
Hummingbird art on Vickie's Sketchbook blog
Cornell's All About Birds:  Rufous Hummingbirds
Bird Banding Laboratory
Birds of North America--I highly recommend subscribing to the online version for detailed descriptions of all North American bird species.

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