Interpretation of findings is also often hampered by the lack of reliable refer-
ence values. For example, although in recent years there have been great advances
in our knowledge of the hematology and blood biochemistry of birds, the data
available largely relate to species that are kept in captivity or have been subjected
to detailed study in the wild. For the vast majority of the world’s nearly 10,000
species of birds, there are no reliable reference values. Likewise, toxicological
investigations can be thwarted because of a paucity of information on what are
“normal” background values, what are sublethal and what are lethal for a given
species. Extrapolation is sometimes possible and the best line of approach, but it
is far from ideal.
The absence of some very basic data is a cause for concern. For instance, the
normal ranges of organ weight and organ/body weight ratios of most species
of birds are not known and yet such information could so easily be gathered
if proper records were kept and findings freely disseminated. There is a great
need to involve scientists of all disciplines, undergraduate and postgraduate stu-
dents, and “amateur” naturalists in filling such gaps in our knowledge.
Comprehensive databases on different taxa of birds are much needed. These
should encompass basic biological parameters as well as information about
organisms (both macroparasites and microparasites) that have been associated
with the species, diseases that have been diagnosed, and published and unpub-
lished observations on pathology. A valuable initial step is the compilation of
checklists of parasites of different species, genera, families, or orders, especially if
linked with studies on the birds’ biology (Storer 2000). Few publications on gen-
eral ornithology include reference to the increasingly important role that infec-
tious agents appear to play in free-living avian populations. Some otherwise
authoritative works include a minimum amount of information about the health
and disease of birds and often even fail to include references to standard texts on
this subject (Marzluff and Sallabanks 1998).
8.7 Legal aspects
There is nothing to stop anyone from carrying out a postmortemexamination. In
some countries, however, including the United Kingdom and many other
European and Commonwealth countries, the making of a formal diagnosis, even
as a result of examining a dead bird, is restricted by law to the veterinary profes-
sion. This is another reason for advocating that those doing postmortemexami-
nations of birds concentrate on recording what they see and not rushing into an
interpretation or “diagnosis.”
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