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1 October 2017 Use of Fine-textured, Mineral-rich Soils by a Northern Flicker (Colaptes auratus) in North-central British Columbia
Roy V. Rea
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Consumption of fine-textured soils by birds is common in South and Central America and some parts of Southeast Asia. Many bird species eat fine-textured soils to aid in digestion, detoxification, and mineral supplementation, but there are few documented cases of such behavior in North America. Here, I describe the consumption of clay soils from an expansive clay bank in north-central British Columbia, Canada by a Northern Flicker (Colaptes auratus L.) in the autumn of 2015. Texture analysis of soils used by the Flicker and collected from the clay bank indicated the soil texture was 61.84% silt, 38.16% clay, and 0.00% sand, which is similar to soils eaten by tropical birds where geophagy has been recorded. Trace element analysis indicated total concentrations of main elements tested ranged from 9 ppm for boron to nearly 40,000 ppm for iron, while minor elements ranged from below detectable limits for mercury, molybdenum, antimony, selenium, and tin to over 1700 ppm for titanium. Total concentrations (1510 ppm) and exchangeable cations (1.5 CMOL /Kg) of sodium in soils used by the Flicker were nearly identical to those found in soils used by tropical birds. Exchangeable cations were below detectable limits for iron and were 4.8 and 7.8 CMOL /Kg for calcium and magnesium, respectively. Total nitrogen, carbon, and sulfur were all below 0.38 weight percent. What drove this Flicker to geophagy is unknown, but the literature and the bird's pattern of use suggest the bird may have consumed these soils as a way to boost mineral intake or as a way to detoxify plant metabolites found in local fruits such as elderberries and wild cherries that Flickers are known to consume.

Roy V. Rea "Use of Fine-textured, Mineral-rich Soils by a Northern Flicker (Colaptes auratus) in North-central British Columbia," The American Midland Naturalist 178(2), 290-297, (1 October 2017).
Received: 28 November 2016; Accepted: 1 March 2017; Published: 1 October 2017

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