But we should come back to considering the typical pattern of molt, how it indi-
cates age, and how the age should be recorded. Apart from some long-lived non-
passerines (e.g. gulls), most species can only be aged as first-year (hatch-year or
within a year of hatch), or older. However, once ringed, a bird marked in its first
year is effectively ageable thereafter. Many species have a distinct juvenile plumage,
grown in the nest. These plumages are typically more cryptically colored than those
of the adult, but even in species in which juveniles have an adult-type plumage, the
feathers are typically downier in texture, especially under-tail coverts and under-
wings, and the underparts and under-wing covert plumage is sparse, leaving bare
areas of skin (novices beware brood patches of adult females, see below). In some
taxa, juvenile remiges (e.g. galliforms) and/or rectrices (e.g. ducks, some passerines)
are more pointed, and because the strength and patterning of feathers differs with
age, as does the time since the last molt, the amount of wear on the tips of primaries
and other feathers may be much greater on juveniles (e.g. shorebirds).
This juvenile plumage is typically replaced during a partial molt (post-juvenile
or first pre-basic molt) a few months after fledging, but still broadly in the natal
area. This molt affects all body plumage, and may affect all or some tail feathers,
but in most species does not affect the primary and secondary remiges or the
greater primary coverts. Molt of the alula, carpal covert and greater coverts may
vary between individuals. All this means that birds with the juvenile-type of
primary coverts and perhaps contrast in greater coverts between old, unmolted
juvenile feathers, and the fresh, molted feathers, may be identified as birds of the
year. Many species will retain these juvenile characters for the next year until they
undergo their first complete molt as a post-breeding adult (post-breeding or
adult prebasic molt). This complete molt includes all feathers and tracts so that
the bird is now indistinguishable from older individuals, but first-years in such
species can be aged while breeding when 1 year old.
This pattern is typical of resident passerines at temperate latitudes (but beware
some species of sparrows, larks, starlings, and a few others that have a complete post-
juvenile molt), but variations abound. Many migrants defer molt until they reach
the wintering grounds, and some species also have a partial pre-breeding body-molt.
These factors can obscure or eliminate the contrast between juvenile and adult
feathers. Again, the details for particular species are available in standard handbooks.
In recognition of these patterns of molt, ringing schemes have devised systems
of age codes that make allowance for deficiencies in available information. The
European (EURING) scheme is widely used and well-known. This is a numeri-
cal code based on calendar years whereby the number increases with advancing
age. Odd-number codes (1, 3, 5, etc.) describe birds whose hatch-year is known,
while even-numbered ages (2, 4, 6, etc.) are not precisely known. Thus a pullus
The bird at close quarters| 101