Retention time was examined in three species. Digestive tracts of
deer mice were well marked at 0 and 6 h after ingestion of a nontoxic
bait, but only one microtaggant was found in one mouse at 24 h. White
rats were well marked at 0, 6, and 24 h, but only one microtaggant was
found in one rat at 48 h. Ground squirrels were marked at 0, 24, 48,
and 72 h.

Mass marking of birds: Eleven red-winged blackbirds and eleven star-
lings were sprayed with an adhesive containing microtaggants to deter-
mine the potential of microtaggants as topical markers on birds. The
treated birds were housed in an outdoor pen and exposed to over 25 cm
of precipitation in the form of snow and rain. The red-winged black-
birds were marked for 90 days. The starlings were well marked for 42
days and then the marking began to deteriorate. At 90 days, less than
one-half the starlings were marked. Starlings appear to have more
oily plumage than redwings and they also spent more time in the water
of the drinker. Both factors probably contributed to the difference
in retention of the marker.

Twenty-four starlings were trapped in nest boxes, banded, sprayed
with an adhesive containing the marker, and then released. Six of
these were recaptured at later dates and each was still well marked.
The marker was present in good concentration at 8 weeks and probably
would have been observable for several more weeks. However, the end
of the nesting season precluded further recaptures and observations.

Nine quelea birds were marked with the particles in a sprayed
adhesive. They were housed indoors for security reasons, therefore,
exposure to wear factors was limited. They were still marked after
90 days.

These trials have provided justification for further work on the
concept of using these particles for mass marking of birds. A field
trial involving the spraying of a large roost of redwings and/or star-
lings by aircraft is being planned. Initial trials with a helicopter
indicate that the concept is workable. Tethered birds were sprayed
and stayed marked for at least a month.

Microtaggants offer a new and promising technique to mark large num-
bers of animals for migration and movement studies and they can be
incorporated into toxic baits for efficacy and secondary hazard inves-
tigations. There are numerous other potential applications. The most
unique feature is the fact that they can be codified so that individ-
ual uses and applications can be immediately and easily identified.
This aspect together with the fact that large numbers of animals
(especially birds) can be marked quickly and easily, are a significant
improvement over current marking techniques.