assessment of wing and body molts. The simplest scheme is to record the state of
progress of molt through the primaries by scoring each feather 0 (old) to 5 (new
full-grown) and summing across all primaries (thus a passerine with 10 primaries
scores 50 when molt is completed). Molt of other tracts can be assessed similarly
as 0 (old), 1 (in molt), or 2 (molt complete), or just recorded as in molt. The
extent of post-juvenile molt (e.g. greater coverts) varies between individuals in
many species (Jenni and Winkler 1994), and may indicate the bird’s age and con-
dition at molt (Gosler 1991).
The condition of the plumage itself, and especially the presence of fault bars
in remiges and rectrices, indicate inadequate nutrition during feather growth,
and are thus worth recording (Murphy et al. 1989). Furthermore, there is evidence
that the growth rates of feathers during molt indicates the bird’s nutritional status
during its growth. Feather structure differs depending on whether growing in the
day or night; a fact that leaves growth-bands across the feather. Thus by measuring
the widths of these bands, the feather’s growth rate can be determined. This
method is called ptilochronology(Grubb 1989, 1995). Ideally, assessment is made
by comparing bars in a tail feather induced by plucking to grow, with those in the
plucked feather. This allows condition to be assessed outside the molt period;
although the width of bars on feathers grown at the usual time has also been used
as a measure of condition during molt (Carlson 1998). Although the value of
ptilochronology has been well-demonstrated (Brodin 1993), its use has been
criticized (Murphy 1992).
4.8.7Parasites
Birds have a number of parasites, which may be important with reference to the
condition of the bird (but be wary of attributing poor condition to high parasite
infestation, since the birds condition may be the cause of the infestation not the
response to it), or of interest in their own right. Ectoparasites include fleas, feather
lice, feather mites, ticks, and parasitic flies such as hippoboscids. Most avian
ectoparasites pose little risk to humans, although some bird fleas will sample
human blood before giving up on it. The presence, distribution, density, and spe-
cific identities of ectoparasites can be assessed visually by searching through
plumage under good light parting the feathers with a paintbrush (rather ineffect-
ive), or by putting the bird into a jar containing ether vapor (e.g. on a cotton-wool
swab), and with its head exposed (Fair-Isle Apparatus), so that the parasites fall off.
Feather mites, which line up between the barbs of the remex vanes, can be scored
(0–5) on each feather by holding the wing up to the light. For further details and
methods see Loye and Zuk (1991).
Birds provide a habitat for endoparasites, chiefly in the blood and gut. Gut
parasites may be obtained from feces collected during ringing but this is likely to
114 |Birds in the hand