Summary
Little is known about indices of health condition in free-living populations and particularly about the presence of significant fluctuations of these indices between years. We assessed blood and immunological condition in wild Hooded Crows (Corvus corone cornix) in NW Italy for three years (1997–1999). Crows did not show any year-to-year difference in erythrocyte sedimentation rate, leukocyte abundance, and heterophyl/lymphocyte ratio. In contrast, we observed significant annual differences in albumin and immunoglobulin values. The albumin/immumoglobulin ratio was lower in 1998, a year when the size of two immunocompetence organs (bursa of Fabricius and spleen) was also smallest. Neither population density nor climate were likely to affect the observed variation of immune condition, annual censuses not revealing any noticeable density variation during the study period, and rainfall and mean temperatures being similar. The results show that in natural populations between-year variation of immune condition may exist, and that in our study, species immunoglobulin assays were more effective than leukocyte counts to detect them.
Zusammenfassung
Über Parameter, die den Gesundheitszustand freilebender Vögel indizieren, ist nur wenig bekannt. Wir haben immunologische Parameter von Nebelkrähen (Corvus corone cornix) in NW Italien über drei Jahre (1997–1999) verfolgt. Die Krähen zeigten keine jährliche Variation in der Erytrozytensenkungsgeschwindigkeit, in der Zahl der Leukozyten oder im Heterophilen/Lymphozyten-Verhältnis. Signifikante jährliche Schwankungen gab es jedoch in den Albumin- und Immunoglobulinwerten. Das Verhältnis von Albumin zu Immunoglobulinen war am geringsten in 1998, in dem Jahr in dem die Größe zweier immunkompetenter Organe (bursa Fabricius und Milz) am kleinsten war. Weder die Populationsdichte noch das Klima scheinen für diese Schwankungen verantwortlich zu sein, da beide während des Beobachtungszeitraum relativ konstant waren. Unsere Ergebnisse zeigen, dass der Immunstatus natürlicher Populationen jährlichen Schwankungen unterliegt, die nicht mit Leukozytenzählung wohl aber durch Quantifizierung der Immunoglobuline nachgewiesen werden können.
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Acquarone, C., Cucco, M. & Malacarne, G. Annual variation of immune condition in the Hooded Crow (Corvus corone cornix). J Ornithol 143, 351–355 (2002). https://doi.org/10.1007/BF02465485
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DOI: https://doi.org/10.1007/BF02465485