Secretarybird Sagittarius serpentarius Population Trends and Ecology: Insights from South African Citizen Science Data Hofmeyr, Sally D. ; Symes, Craig T. ; Underhill, Leslie G. Abstract Publication: PLoS ONE Pub Date: May 2014 DOI: 10.1371/journal.pone.0096772 Bibcode: 2014PLoSO...996772H