Color Infrared Photography Is Not a Good Predictor of Macro Invertebrate Abundance on Mudflats Used by Shorebirds

The applicability of color infrared photography to indirectly predict prey abundance for shorebirds was tested by measuring the chlorophyll concentrations of primary producers on the mudflat surface at eleven migratory stopover sites of shorebirds in Georgia Strait, British Columbia during southward migration in July and August 2002. Many shorebirds are associated with regions of high coastal zone productivity, which may contribute to high prey abundance. Chlorophyll levels of primary producers contribute to the red tones of an infrared photograph. The hue of an infrared photograph was positively related to the chlorophyll concentration of the sediment surface across all sites. However, invertebrate density was not strongly related to surficial sediment chlorophyll concentration or photograph hue. The color infrared photography method is useful to quickly assess the surficial sediment concentration of the phytobenthos, but of low value to estimate invertebrate prey densities.