Temperature changes of the hypothalamus and body core in ducks feeding in cold water.

Hypothalamic (Thy), spinal(Tsc) and colonic (Tc) temperatures were measured in Pekin ducks spontaneously dabbling for food in cold water (5 degrees C). In agreement with observations in the pigeon and the fowl Thy was found to be consistently lower by about 0.5 degrees C than the other core temperatures. The drop of Thy during dipping head and neck into the cold water was not substantially greater than that of Tsc, while both changed more than Tc. The measurements do not support the assumption that the hypothalamic region in the duck is exposed to substantially greater temperature fluctuations than other thermosensitive parts of the body core.