Percent of living mother-calf pairs and dead calves with and without lesions by decade.

Sample size is indicated between parentheses. Data were collected from aerial survey photographs of living mother-calf pairs in the period 1974–2011 and necropsy photographs of dead calves in the period 2003–2011. NA: no data available. Percent of living mother-calf pairs and dead calves with and without lesions by decade.