The physiological effects of high blood lead levels in the House sparrow

Lead is a heavy metal that is often found in high concentrations as a contaminant of urban and industrial environments. Physiological effects of lead on organisms are found to cause negative impacts across neurological, renal, immune, reproductive, haematopoietic, and endocrine systems. The aims of the project were to determine the physiological effects of blood lead levels in a population of house sparrows in the mining town of Broken Hill, NSW, Australia. We took morphological measurements of the sparrows, and collected blood to determine blood lead levels, haemoglobin concentrations and packed cell volume, heterophil/lymphocyte ratios, and reticulocyte percentages. We report blood lead levels >50μg/dL in over 27%, and >100μg/dL in almost 9% of sparrows sampled, indicating significant lead exposure in the population due to environmental contamination (Franson and Pain, 2011). We found a significant negative relationship between haemoglobin and blood lead levels (P = 0.003), where individuals with higher blood lead levels had lower haemoglobin levels by around 6%. Unexpectedly, there were no relationships between lead and body condition index, heterophil/lymphocyte ratios or reticulocyte ratios, suggesting that other effects on physiology were limited. This study provides important information on how a bird population is coping with high levels of lead exposure from ongoing environmental pollution.