Foraging rates (arthropod consumption [g/min/chick]) of human-imprinted chicks provide a reasonable metric for assessing the quality of brood-rearing habitats for gallinaceous species. Arthropod foraging rates have been estimated using dry mass or allometric equations of crop and gizzard contents, and internal surgical ligature of the crop. Current methods are time- and labor-intensive. We describe a new method to estimate foraging rate using chick mass change (g/min) during a 30-min foraging trial.
Our technique requires surgical tissue adhesive be applied to the cloaca to prevent bias in mass change measurements caused by defecation. We compare our mass change technique to a published internal surgical ligature technique using human-imprinted ring-necked pheasant chicks. Chicks treated with tissue adhesive had rates of mass gain (0.012 g/min, SE = 0.004) similar to ligatured chicks (0.006 g/min, SE = 0.004, F1,58 = 3.16, P = 0.0805). In contrast to the surgical ligature procedure, we found tissue adhesives can be applied quickly in the field and provide an efficient means to evaluate foraging quality of brood-rearing habitats. We provide suggestions for a set of standardized protocols for the use of imprinted chicks.