Case Study: A Split–brood Comparison of Formula for Nestling Songbirds (FoNS ) versus Three Facility–specific Diets

Thirty–four nestling birds of seven species were used to test whether Formula for Nestling Songbirds (FoNS ) would result in better weight gain, feather growth, and survival rates compared to inexpensive control diets. Ten broods, of 2 to 5 birds, were split into two groups. Some of each brood received FoNS  while others received one of three species specific and facility–formulated control diets. Four species (Bewick’s wren [Thryomanes bewickii], red–eyed vireo [Vireo olivaceus], violet–green swallow [Tachycineta thalassina], and black–capped chickadee [Poecile atricapillus]), received a control diet consisting of dog food supplemented with bone meal, brewer’s yeast, and protein powder. With the exception of the swallows, birds on this control diet generally lost weight, and three of the five died; whereas all six birds from the same broods survived and gained weight on FoNS . Two species, (house sparrow [Passer domesticus] and house finch [Carpodacus mexicanus]) received control diets of chick starter with cat food, hard boiled eggs, bone meal powder, and peanut butter, and one species (European starling [Sturnus vulgaris]) received a control diet based on dog food. For these species, the FoNS  diet and control diets showed similar development, growth, and no deaths. The authors suggest that FoNS  diet is advantageous, especially for small, insectivorous species, but some inexpensive alternatives may be equally suitable for certain species.