Correlation between Rhythmic Changes in Body Temperature of Small Passerine Birds (Chloris chloris) and Nontidal Gravity Fluctuation in a 12- to 30-min Period Range.

In view of an association observed previously between animal activity and deformational changes in the lithosphere, the phenomenon was investigated with the example of time-related changes in the body temperature of male common greenfinches (Chloris chloris) and gravimetric data. A stable positive correlation was observed between changes in bird body temperature and changes in gravimeter readings, but only in the time interval when the birds were active. The power of prevalent harmonics was shown to change simultaneously in body temperature and gravimetric data dynamics for periods ranging from 12 to 30 min, suggesting an association between the two processes. Fluctuations in gravimeter readings in the 12- to 30-min range of periods was therefore considered as a marker of a yet unidentified biotropic environmental factor that affects animal activity.