Metals in feathers of black-crowned night-heron (Nycticorax nycticorax) chicks from the New York Harbor Estuary

Abstract

In heavily urbanized landscapes such as the New York Harbor Estuary, the local environment is subject to a variety of contamination sources. Environmental contaminants such as heavy metals and metalloids pose a risk to wildlife inhabiting the harbor. Metal concentrations in feathers indicate exposure and provide insight into the potential adverse effects on birds. In 2004 and 2005 down feathers were collected from 147 black-crowned night heron (Nycticorax nycticorax) chicks living on four island colonies in the New York Harbor Estuary, USA: Goose Island, Hoffman Island, North Brother Island, and Canarsie Pol. We examined geographical and interannual differences in concentrations of the metalloid arsenic (As) and the heavy metals cadmium (Cd), chromium (Cr), lead (Pb), and mercury (Hg). Significant differences in metal concentrations were a function of location, with North Brother Island having the highest As concentrations and Goose Island having the highest Cr and Pb concentrations in feathers collected in 2004. In 2005, feather samples indicated Hoffman Island had the highest Cr concentrations and North Brother Island had the highest Pb and Hg concentrations. Concentrations of As, Cd, and Hg decreased significantly from 2004 to 2005 on North Brother Island, Hg on Hoffman Island decreased from 2004 to 2005, while Cr on Hoffman Island increased from 2004 to 2005. Cd and Pb concentrations were higher and As and Cr concentrations were generally lower than concentrations reported in previous studies. Further investigation is necessary on the declining population of herons in the New York Harbor Estuary to determine specifically if birds are experiencing adverse effects from metal contaminants, or if organic contaminants, such as organic Hg or polychlorinated biphenyls (PCBs), are playing a role in this population's decline.