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Pictorial Highlights, Advanced Bander Development Workshop

September 2010

We host several Bander Development Workshops at Powdermill during the year.  Our beginner workshop focuses on bird banding basics.  This includes how to set up and take down mist-nets, handling, banding, and extracting birds from nets, and collecting data on wild birds.  The emphasis of our advanced workshops is to train banders on techniques used to age and sex birds.  Much of the time is spent gaining a thorough understanding of avian molt and applying that to ageing birds.  This relies on the ability to distinguish juvenile feathers from adult feathers, a difference that is often quite subtle.  As a result, it is very difficult to learn how to age birds using molt limits on your own.  Most banding stations in North America rely on "skulling" to age birds during the fall, but this technique cannot be used in the spring as young birds have completely developed skull bones at that time.  On the other hand, the same molt limits used to age birds in the fall can not only be used in the spring but are even more obvious at that time.  The ability to age birds is important because obtaining accurate ages can help researchers evaluate breeding productivity and habitat quality, two very important aspects of avian conservation. 

Please contact PARC at 724-593-7521.

The following photos are from our latest advanced workshop, and will give you an idea of what participants learn during the workshop.

Apple Blossoms Several of the workshop participants ageing a bird by looking for the presence or absence of a molt limit among the wing feathers. 
Student Conservation Association (SCA) program A group photo from the Advanced Bander Development Workshop. 
Blooming marsh marigold A hatching-year (HY) Gray-cheeked Thrush.  Notice the molt limit where the inner 2 greater coverts were replaced during this bird's 1st prebasic molt while the rest of the greater coverts are retained juvenile feathers.   This is the typical pattern shown by all HY  thrushes of the genus Catharus.
Mourning Cloak Hatching-year Wood Thrush show a similar pattern; they often replace more inner greater coverts than the Catharus Thrush.  This individual has replaced the inner 5 greater coverts; the outer 5 are retained juvenile feathers.  Although this molt limit is a little more difficult to see in the photograph, it comes out much better while viewing the wing in good light. 
Tree Swallow The hatching-year warblers show a somewhat different pattern than the thrush where they typically replace all of the greater coverts, the carpal covert, and the alula covert (often referred to as A1).  However, some individuals keep some outer greater coverts.  This Ovenbird has retained 2 outer greater coverts but replaced the carpal covert.
Robin Feathers


Hatching-year Gray Catbirds usually have a molt limit among their greater coverts.  This juvenile bird has only replaced the inner few greater coverts and the outer 5 are retained juvenile feathers.

This HY Black-billed Cuckoo has a lot of retained juvenile feathers, including most of the greater coverts and the larger alula feathers.

Like the Ovenbird above, the HY Red-eyed Vireo retained 3 outer greater coverts.

Second Year Robin Fealthers This Rose-breasted Grosbeak can be identified as a SY male.  He was still undergoing the prebasic molt and the last secondary to be dropped is very brown, indicating it is a juvenile feather.
male cowbird On the other hand, this individual was identified as an ASY male.  It too was still undergoing its prebasic molt, but the feathers yet to be dropped and replaced (S 4-6) are darker and represent adult feathers with 1 year of wear.  Interestingly, the white wing patch is larger on the younger bird (above).
female red-winged blackbird An AHY male Indigo Bunting.  The blue edging on the primary coverts reveals this to be an adult bird.  HY males and females will have brown primary coverts, while adult females will have primary coverts colored with a mix of browns and blues.
Male Rusty Blackbird An AHY male Black-and-white Warbler.  Notice the lack of a molt limit within the alula feathers. 
Female Cardinal Blue Jays can be aged by the presence or absence of black barring in the alula and primary covert feathers.  This bird has extensive barring and was aged an AHY bird.  This criteria is well illustrated in the Pyle Guide to Ageing and Sexing passerines.
Male cardinal   This AHY male Magnolia Warbler has undergone a complete prebasic molt (therefore aged AHY).  The black streaking on the back and flanks and extensive black in its uppertail coverts along with its long wing chord (61.5 mm) was used to identify it as a male.
Male Towhees

Towhee Wing

This is a HY female Magnolia Warbler.  This was a very dull bird with little black streaking anywhere.  Like some of the other examples in this section, this bird has retained the outer 3 greater coverts.  It has replaced the carpal covert (darker gray feather) and all 3 alula feathers are retained juvenile.  Remember that most individuals of all the warbler species will replace all of their greater coverts during the first prebasic molt.

Eye color is also a good characteristic to assist in ageing a number of species in the fall.  This is most pronounced for some vireos (Red-eyed, White-eyed), woodpeckers, Eastern Towhee, and raptors.  Although more subtle in some other species, it is very helpful for ageing Gray Catbirds (everybody gets a lot of these!).  Adult catbirds will have a dark brown eye where it is difficult to separate the pupil from the iris (left), and HY birds have a light brown iris that is clearly distinguishable from the pupil (right).
ASY and an SY male Purple Finch Notice the red eye on this adult female Red-bellied Woodpecker.

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