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European Association of Zoos and Aquaria

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download-button-0409-lg 6th European Zoo Nutrition Conference, Barcelona 2010 - Proceedings

 

ABSTRACT

Hand-reared common swifts (Apus apus) in a wildlife rehabilitation centre: assessment of growth rates with different diets

Enric Fusté, Laura Olid and Elena Obon

Centre de Recuperació de Fauna Salvatge de Torreferrussa (Departament de Medi Ambient i Habitatge, Generalitat de Catalunya). Ctra. Sabadell/Sta. Perpètua de Mogoda, km 4,5. 08130 Santa Perpètua de la Mogoda, Catalunya, Spain

 

Common Swift orphans represent an important number of admissions in rehabilitation centres in Europe. Being an altricial species, chicks require hand-rearing for survival. Swifts are insectivore birds, which represent a real challenge when designing diets in captivity. An insect diet based in crickets is used in some specialized rehabilitation centres in Europe to hand-rear swifts, being optimal in aiding recovery from poor body conditions at admission, reaching optimal fledging weights and feather condition. Many wildlife rehabilitation centres may encounter difficulties in the hand-rearing of large numbers of chicks using commercially available insects as they are expensive food items. These constraints create the necessity of having alternative diets which take into account cost, effort and accessibility. Until 2008, Torreferrusa wildlife rehabilitation centre (CRFST) in Barcelona was using a diet based on rat mince to feed the orphans. In order to assess the performance of this diet, a group was created to compare growth rates during the hand-rearing process and body weight at release to those of wild parent-raised common swifts. Some variables, such as clinical condition at admission, were predicted to have some influence. Weight, feather condition and general behaviour were recorded daily. The results showed significant differences in final weights, being remarkably lower for hand-reared animals on the rat mince diet (Rat mince 32.8g SD ± 2.7 vs. Wild 42.6 SD ± 3.9). There was not a significant correlation between final weight and clinical condition. In 2009 CRFST expanded the diet study including three additional diets, a diet based on the FoNS 08 © formula, where the main ingredient is a high protein-low carbohydrate cat food, a diet based on crickets (90% Acheta domesticus, 10% Galleria mellonella) and another group using exclusively mealworm (Tenebrio molitor). Both supplemented with vitamins and minerals. The mealworm diet is quite controversial, as some non peer published sources attribute health problems in long run feeding. However, it is used successfully in hand-rearing Chimney swift (Chaetura pelagica) in the US. Three histopatological evaluations of tissues have been requested to observe if there was any damage to internal organs (results still to be confirmed). The final weight results in both insect diets groups were highly satisfactory, with values close to those in the wild (Cricket 40.1g SD ± 4.2 – Mealworm 40.3g SD ± 3.1). All birds, even emaciated at admission, were released in perfect conditions. The results for the FoNS 08 © formula were not optimal as expected with the final weights (33.5g SD ± 4.2) although the birds attained an excellent feather condition and the flying performance at release was remarkable when compared to those observed on the rat mince diet. FoNS 08 © did not work well with very young chicks and birds in poor condition, which were switched to the insect diets. Under the circumstances the pure insect diet can not be provided for economical reasons and still we can not propose a satisfactory non insect base diet, the results of this research encourage and support the necessity to implement changes in the protocols for the upcoming season, and continued research to improve diets.