Relations between the Leukocyte Profile and the Energy State, Hematocrit, and Blood Metabolites in the Great Tit (Parus major)

The health of animal populations can reflect ongoing changes in their environment. Various physiological parameters can be used to assess individual and population conditions. These parameters may be interrelated or independent, allowing for organisms to respond flexibly to environmental changes. We...

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Bibliographic Details
Published in:Biology bulletin of the Russian Academy of Sciences 2022-12, Vol.49 (8), p.1171-1185
Main Authors: Volkova, A. A., Berezantseva, M. S., Afonov, K. I., Spiridonov, A. V., Polikarpova, D. R., Zhukova, E. A., Demina, I. V., Tsvey, A. L.
Format: Article
Language:English
Subjects:
Autumn
Biochemistry
Biomedical and Life Sciences
Blood glucose
Cell Biology
Ecology
Energy
Environmental changes
Environmental conditions
Glucose
Hematocrit
Hypoglycemia
Immune system
Leukocyte migration
Life Sciences
Locomotor activity
Low temperature
Lymphocytes
Metabolites
Parus major
Physiology
Population studies
Thermogenesis
Zoology
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Summary:The health of animal populations can reflect ongoing changes in their environment. Various physiological parameters can be used to assess individual and population conditions. These parameters may be interrelated or independent, allowing for organisms to respond flexibly to environmental changes. We investigated the dynamics of the leukocyte profile (total number and relative proportions of various types of leukocytes) in an urban population of the Great tit ( Parus major ) during two stages of the annual cycle: autumn migration and wintering. We also analyzed the relations between the leukocyte profile and the energy state, hematocrit, and the levels of blood metabolites (glucose and β-hydroxybutyrate). We found the total number of leukocytes and lymphocytes to be higher during autumn migration compared to wintering, which indicates a more active state of the immune system in Great tits during migration. An increased number of lymphocytes (specific immunity) can reflect high probability of encountering already familiar infections during the relatively short-distance migrations typical for this species. The ratio of heterophils to lymphocytes (H : L ratio, a measure of long-term physiological stress) in this population was higher in winter than during autumn migration. We assume that this may be caused by low temperatures and increased competition for food in wintering birds. The total number of leukocytes correlated positively with energy reserves and negatively with the blood glucose level, possibly indicating a coordinated response of these physiological parameters to environmental cues. Our results also show that birds that have adequate energy reserves and low blood glucose concentrations (i.e., are in good condition) maintain a more active immune system. Reduced energy reserves (e.g., due to unfavorable feeding conditions, higher energy costs of both locomotor activity and thermogenesis in cold weather) caused an increase in blood glucose concentrations and a decrease in the number of leukocytes. The H : L ratio was not correlated with other physiological parameters, showing that the level of long-term physiological stress was related to neither the individual energetic condition nor the level of metabolism in Great tits under the observed environmental conditions. Taken together, our results show a low level of long-term physiological stress in the studied population of Great tits.
ISSN:1062-3590
1608-3059
DOI:10.1134/S1062359022080222