Bird Ecology and Conservation A Handbook of Techniques

of relevant samples for morphometrics or study of gross or microscopical

morphology. In some cases, the bird’s carcass and or tissues may be required

for a “Reference Collection”—see later. The likely fate of carcasses, tissues,

and specimens should, therefore, be assessed beforethe examination is carried

out. Appropriate containers will be needed and a decision made as to how

best to preserve the material. The latter is an important consideration; thus,

for example, tissues for histology can be safely stored in 10% buffered for-

malin but this method of fixation may prove deleterious for studies on DNA.

Freezing will preserve most microorganisms and poisons but will hamper

subsequent histology or electronmicroscopy. Plastic bottles may produce

erroneous results if used to store samples for certain toxicological analyses.

Facilities for storage of bodies and tissues may be limited, in which case a decision
has to be made as to what is retained and for how long. As a general rule, following
apostmortemexamination, the bird’s carcass and tissues can be kept in a refrigera-
tor ( 4 C) for up to 5 days, after which, if still needed, they should either be frozen
( 20 C) or fixed in formalin or ethanol. Often it is wise to save aliquots of tissue
using a combination of fixation methods, for the reasons cited above.
Material should be retained for future reference or retrospective studies when-
ever feasible (Cooper and Jones 1986; Cooper, Dutton, and Allchurch 1998). If
a specific Reference Collection exists, the carcass should be fixed in totoin for-
malin other than small portions of tissue, for example, liver, which should be
frozen or (less satisfactory) fixed in ethanol for DNA work. Complete carcasses
are sometimes used for analysis, to measure body composition, as part of assess-
ing “condition.”

8.5 Laboratory investigations

Laboratory investigation of samples is a key part of postmortemexamination of
dead birds and investigation of sick or dying ones. A whole range of tests can be
used and the choice depends upon:

(a) The indications in the field: birds found dead after a spillage of chemicals

are likely to warrant toxicological examination rather than culture for

bacteria, fungi, or viruses.

(b) The resources available. Many laboratory techniques are expensive and

the cost of some may be prohibitive. Sometimes funding permits a selec-

tion of tests to be done on a proportion of the birds. Often samples have

194 |Information from dead and dying birds