ARTACHO, P.*; CASTA�EDA, L.E.; SOTO-GAMBOA, M.; VERDUGO, C.; NESPOLO, R.F.; Univ. Austral de Chile; Univ. Austral de Chile; Univ. Austral de Chile; Univ. Austral de Chile; Univ. Austral de Chile: Haematological Parameters As Tools For Evaluate Physiological Status In An Endangered Black-necked Swan Population.
Haematology is a useful tool to assess the physiology and health status in wild vertebrates. In this work we studied the haematology of black-necked swans (Cygnus melanocoryphus) at the �Carlos Andwandter Sanctuary� (site Ramsar 6CL001), located at Cruces River, Chile. This species was experiencing a serious population crash at this conservation area since population size was reduced in 95% during 2004. This was a consequence of a drastic reduction of the waterweed Egeria densa, -their main food- related with water pollution due to recent industrial activity upstream of the Cruces River. We captured 112 adult birds between August, 2004 and March, 2005 at the Sanctuary. As control we used a dataset from 29 animals sampled in 2003 in the same location. Blood samples were taken from humeral vein and transferred into tubes with anticoagulant, and six haematological parameters were determined. Results showed that body condition decreased through time, which was more pronounced in females. Haematocrit, hemoglobin, erythrocytes and leucocytes changed in the same fashion with sampling date, being reduced principally to the end of the period. Neither mean corpuscular volume nor mean corpuscular haemoglobin concentration changed during this time. It has been described that the first consequences of malnutrition and/or fasting in vertebrates is the reduction of haematocrit levels and a decrease in hemoglobin and erythrocyte count. Our results are in concordance with these findings but we also detected a reduction of leucocytes count which indicates immunological depression. We conclude that this otherwise slight level of malnutrition was enough to prevent reproduction, increase juvenile mortality and induce the almost total emigration of swans.
