What should you feed a Swift?

Any experienced Swift rehabber will tell you that giving Swifts a diet of catmeat, mealworms and the like will have disastrous consequences. Yet, intuitively, that's what most of us would do if we didn't know better. Well-meaning, but misguided, we reason that the Swift is an insectivorous bird, so it will welcome a substitute meat diet if we haven't got any insects to hand.

So, we know anecdotally that you should avoid certain foods when bringing on a Swift, but now there is scientific evidence to support the assertion. An article appearing in a recent issue of JZAR, the Journal of Zoo and Aquarium Research describes the results of an experiment carried out by Enric Fusté and colleagues at the Centre de Recuperació de Fauna Selvatge de Torreferrussa in Catalunya.
The team hand-reared a total of 116 chicks which they divided into four groups, each fed a different diet:

Diets with good results for Swifts:

1. cricket diet, based on house crickets (Acheta domesticus) and wax moth larvae (Galleria mellonella)
2. mealworm diet, based on mealworm larvae (Tenebrio molitor). 

Two “meat” diets were also tried with much worse results:
3. rat mince diet, a specific pathogen-free laboratory rat mince; 
4. kibble diet, a formula based on a high-protein–low-carbohydrate cat food; 
and two “insect” diets: 
All the chicks were given vitamin and other supplements to ensure that they were not put at undue risk.

The results were clear: birds fed on the meat diets (3 and 4) had significantly lower weights than those fed on diets (1 and 2). Additionally, features such as feather growth and feather quality were significantly lower in the meat-fed groups. You can download a pdf file of the complete report here. We are also fortunate that Enric Fusté is giving a talk at our Cambridge International Swift Conference next April.