• Wednesday, April 14 - Thursday, April 15....Wednesday efforts were cut short by morning and afternoon showers, but Thursday, while not much of an improvement as far as number of birds banded, netted us two new species for the spring.  Carolina Wren and an ASY male Eastern Towhee (photo below).

• We banded three more Eastern Towhees this week, all of which were second year (SY) males.  While we've discussed the use of soft parts in ageing on the website before, we thought these birds provided us a good opportunity to broach the subject again.


Eye color can be a helpful criteria for ageing birds in the hand when used in conjunction with molt limits and tail shape.  Eye color typically progresses from having a dull brown or gray cast in immatures to a brighter deeper colored eye in adults.  While there are different color variations between species, for example, a gray eye turning white in White-eyed Vireo and a brown eye turning red in Red-eyed Vireo, for most, adult birds will have a brightly cast, darker colored eye, and immatures will exhibit a dull cast, gray or brown eye, as seen here in the towhee photo below.  While this contrast is often subtle, when compared with the photo above, the picture below exemplifies this difference well (note also the retained worn and brown juvenal alula feathers on the bird in the photo below).

As always, there are exceptions to the rule, and the bird in the photo below is one of them.  It too, is an SY bird (note the molt limit among the molted tertials, retained outer secondaries and the adventitously replaced inner flight feathers, and also the very worn, brown juvenal primary coverts), but its eye color more closely resembles that of an adult in brightness and color.  This is the reason that eye color is usually used in age determination only when in conjunction with a more reliable characteristic like molt limits.

• On Sunday, April 18th, we banded another first for the spring.  An SY male Brown-headed Cowbird.

• Discerning molt limits in birds starts with a basic knowledge of a species molt pattern.  Hatch year (HY) blackbirds, as a group, have a complete first pre-basic (fall) molt, meaning all of their wing feathers are replaced shortly after leaving the nest and therefore resemble those of an adult (i.e. no apparent molt limits).  So, how then are we able to determine the age of the Cowbird above as being a SY?

• Also on Sunday, we banded this SY male Red-winged Blackbird, which following along with our excpetions to the rule from with towhee above, had retained flight feathers, secondary 1 and primaries 1-3 from left to right on the wing.  Tertials 8 and 9 (the innermost secondaries) and the inner few greater coverts also appeared juvenal being more worn, brown and not as neatly edged.

• Tree Swallows arrived at Powdermill on April 3rd, but not until this weekend did they come in numbers and start competing for residency of the "Bluebird" box.

• With many new swallows around it was inevitable that we would capture our first for the season.  Below is one of four new birds banded this weekend.

• In conclusion, on Saturday, April 17th, Powdermill's banding program experienced what we think was a first ever occurrence in the history of the 43 year old program..........

• A banding demonstration was given to some visitors and not a Bob was to be found.  Bob Leberman, after 43 years as senior bird bander, is practicing semi-retirment, and Bob Mulvihill, the second primary bander at Powdermill for the last 25 years, still resident here, now has his plate quite full as State Project Coordinator for the 2nd PA Breeding Bird Atlas.

Last Updated on 4/21/04
By Adrienne J. Leppold