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Notes on HAND-REARING SWIFTS


INTERVENTION

Several hundred thousand injured and orphaned birds are admitted in wild rehabilitation centres every year around the world. Juvenile of the common urban areas represent a significant proportion of wildlife casualties admitted in rehabilitation centres. Only in Torreferrusa Wildlife Rehabilitation Centre (CRFST), in Catalonia, more than 2000 orphan swifts are admitted every year.

Some causes for falling out of the nest. In the early stages, parents pushing the young unintentionally out of the nest, young suffering in the heat and scrambling to the entrance or young jostling for a position near the entrance to monopolize parental attention. Possibly nestlings felt out more frequently in enlarged brood size nests, due to sibling competition and brood reduction. Nestlings in poor condition were more likely to disappear from the broods. In the later stages of the breeding period, it has been observed that when parents readily deserted their nestlings, fledglings stayed restless for several days in the nest but eventually, the starving young climbed off the nest to fall to the ground where soon perished.

HAND REARING ALTRICIAL YOUNG

Altricial nestlings less than two to three weeks, for most of the species, are easiest to adapt to the hand-rearing process. This is particularly accurate in swifts, as they beg and grasp easily the food. We can emphasize the importance of the young development, as a chick with a poor start may develop clinical problems later in life. They premised how a poor development may be caused by any factor interfering with the homeostasis of the chick; improper feeding, poor environmental conditions in early development or diseases, such as subclinical diseases which cause the chick expending energy fighting the disease instead using energy for growing.

HUSBANDRY GUIDELINES

Kyle & Kyle (2004, 2007) published husbandry guidelines for the chimney swifts (Chaetura pelagica), an American species. Although housing and release criteria may require adaptation based in individual species’ natural history, they made general recommendations that may be appropriate for other swift species. There are not an established protocols or published information covering the husbandry and hand rearing of common swift, although different organisations and wildlife rehabilitation centres provide recommendations on their websites.

INITIAL CARE

In CRFST, once a nestling swift is admitted in the centre, a physical examination is performed. Nestlings are categorised based in their body condition, mentation and clinical signs. Body mass is assessed by noting the thickness of the muscle and possible subcutaneous fat. This category defines the initial care of the young, such as initial treatment, housing, feeding diet, and posterior following up. Most of the birds are considered to be dehydrated, though oral fluid therapy is administered prior feeding the bird with any solid food. Oral rehydration is effective and safe, although in severely dehydrated animals, fluids may be injected subcutaneously. The oral rehydration compounds are Glucolyte Braun© and Ringer’s Lactate solution, which provides carbohydrates and electrolytes. Feeding a cold or dehydrated chick could be dangerous, even if appears to be hungry, as they digestive capacities are not fully recovered. Kyle and Kyle (2007) recommended for oral rehydration of chimney swifts, Gatorade© which provides carbohydrates and electrolytes and Nutri-cal© (EVSCO Pharmaceutical) which provides readily available calories without overloading the digestive system. They also recommend a protocol based in the consistence of the faeces, administering oral rehydration until at least the second stool have a normal appearance, with faeces enclosed in a mucus envelope. Then the bird can be moved to a complex protein or a solid food diet. Sometimes it may be necessary to stimulate the defecation in some nestlings. It is recommended special care in oral rehydration in depressed or chicks that are not swallowing well, as the risk of aspiration of fluids into the respiratory track is important. In such circumstances fluid should be administered subcutaneously.

The most common problems encountered at admittance of swift nestlings are dehydration, weakness, emaciation and feather poor condition. External parasites are often found (e.g. biting lice) and may be treated with fipronil (Frontline©, Merial), to provide relief and to prevent spread to other birds. If during the initial trial a bird is not considered suitable for later stage release it is humanely euthanized.

HOUSING

It is recommended housing new admissions in an incubator to speed volume repletion by providing an environment with high humidity. Once stabilized, older chicks require less thermal support. Cavity nesting species, such as common swifts may feel more comfortable in soft lighting or dark enclosures. Nestlings younger than one week, still not covered by down, thus still unable of regulating their body temperature effectively are housed in enclosures that maintain a warm constant temperature and humidity. They have to be kept in small pet carriers with ventilation holes, with a soft towel in the base, covered with paper. Older nestlings are kept in cardboard or plastic boxes, 500 x 500 x 500 mm, thus fledglings may start exercising. The bottom is covered with absorbent paper which is changed each feeding time, aiding in the removal of droppings.

DIETS

Ideally, nestlings in captivity should be fed exactly the same foods the parents would have fed them in the wild; however, duplicating this is and extremely challenging task. Wildlife rehabilitation centres dealing with insectivore species may encounter difficulties in the hand-rearing of large numbers of chicks, as there is a limited selection of commercially available insects and they tend to be expensive item foods. These constraints create the necessity of having alternative diets which take in account cost, effort and accessibility at the same time of provide and excellent plan of nutrition for orphaned birds.

There is some controversy in regard to the dietary methods used in common swifts. Many foods fed to young insectivore passerines are completely inadequate and never should be used. Meat, dog food, bread, cheese or milk between other foods are usually given by privates before care of professional careers. In common swifts, some items of animal origin have been proved to be extremely harmful, when fed to young birds. They cause health and feather problems along the hand-rearing, jeopardizing its release to nature.

Sswifts are exclusively insectivorous, thus their substitute diet must be comprised of insects. Kyle & Kyle (2004, 2007) election diet in hand-rearing chimney swifts, and also used in Vaux swift (Chaetura vauxi) is comprised of small and medium mealworms (Tenebrio molitor), mineral and vitamin supplements, nutritional yeast, plain active-culture yogurt (Lactobacillus acidophilus), and distilled water. They use a specifically designed diet based in their 20 years’ experience and more than 1000 birds released back into the wild, with extensive post-release, breeding success and post-migration data. Similar diet has been adopted by CRFST, which extensively details will be provided in other posts in this site. Two birds under this diets has been recovered some years after release.

Haupt (2008) use a diet based mainly in crickets (Acheta domesticus) and occasionally wax moth (Galleria mellonella) larvae, supplemented with minerals and vitamins. In addition, vitamin B is injected subcutaneously every 2 weeks. A young hungry swift may eat as much as 20 crickets (15-20 mm) each feed time (± 3.5 g), number that decreases as birds grow.
Birds are fed six times a day.

BWH (2008) recommends a diet composed of fleshly chopped white maggots (8-12 per chick) and mealworms (5-8 per chick), wax worms and crickets can also be used, mixed in a complement mixture of liquidized chicken feline maintenance biscuits (Hills © or Ians ©) and hydrated insectivorous bird food. This mixture is supplemented with minerals and Avipro©, a probiotic combination of bacteria, enzymes, electrolytes and vitamins. The liquidized diet is administered with a syringe, down the throat into the oesophagus, with a gentle wiggling motion to induce swallowing. Birds are fed 1½ ml to 2½ ml five to six feeds a day.

Other authos recommend diets for insectivorous species composed of several ingredients (Water, canned and dry feline growth food, hard-boiled eggs, gelatine, calcium, ascorbic acid, powdered complex vitamins, body fish oil, vitamin E oil and plain yogurt), which are administered in a proportion of 6ml altogether with 10 large mealworms, 5 wax worms and 3 large crickets (amounts varies for each insectivore species).

Matthes (2006) described a diet based in white and brown drones (Apis mellifera), crickets, dried insect pellets mixed with the liquid of white drones, green bottle fly (Lucilia ceasar) , black-flies (Musca domestica), wax moth, calcium and vitamin complements (Beo specials, Vitakraft ©). It is interesting to describe this diet as a bird hand-reared by this author was recovered a year later in good condition when was prospecting for nesting sites.

Hand-rearing formula need the calcium and phosphorus balanced in 2:1 ratio by weight, with calcium comprising 2 per cent of the diet dry weight, in order to avoid development of metabolic bone disease in chicks. Kyle and Kyle (2007) stated that metabolic bone disease in swifts was rare, thus low calcium concentration of their diet should not be of concern. Aerial plankton that comprises the natural swift diet is low in calcium, being evident in the thin shell of the swift eggs.

Birds respond differently at accepting the food. Young nestlings usually respond by bobbing their heads, chattering loudly and gulping anything close, thus they are easy to be feed. As they grow, fledglings may have to be force-fed. In this case, the bird is hold gently, the bill is opened very carefully with a fingernail and the food placed in the mouth. Usually the bird swallows the ball mince or the insects, helped with some drops of water placed on the bird’s bill to facilitate swallowing.

Careless feeding techniques lead to feather damage, with possible follicle, skin and eye damage. In any diet, it is very important to wipe the beak and under the chin with a damp tissue to remove any food stick to the feathers or flushed from the eyes with ophthalmic saline solution.

Food digestion in wild nestlings is also contributed by the action of the saliva, which soften and usually have an enzymatic action. Some researchers suggest the use of digestive enzymes (e.g. Pancreazyme © Virbac) in 1-3 days old altricial birds. In the wild, the normal intestinal flora in nestlings is established by parents when feeding. Nestling also uptake microflora from the environment through spontaneous sucking movements of the vent, for colonization of the posterior digestive tract. Also emphasised the importance of providing faecal microflora for gut colonization in young birds, by giving twice a day a little amount of fresh faeces from a healthy adult. Kyle and Kyle (2007) stated that chimney swifts less than 7 days old may not have fully inoculated digestive tracts with substandard immune competence. They use adults as saliva donors, feeding the young three times a day a mealworm that has been swabbed in the throat of an adult. This procedure, repeated until birds are 10 days old, reversed a previous 100% mortality rate in chicks less than 7 days old.

RELEASE

A perfect plumage is vital for such specialized aerial flyers. Thus it is important to do a triage, based in the feather condition, during the process of hand-rearing swifts. Birds with a deficient plumage will be condemned to death when released. Stress marks, or fault bars on feathers are translucent bands, caused by defective barbule formation and may be points of feather breakage. They are associated with stressful and adverse conditions, especially malnutrition during feather formation. It indicates a release of corticosteroids while feather was developing, and are common in neonates that have had a disrupted feeding. Caregivers should beware of becoming so familiar with feathers of low quality that it appears normal. Plumage of hand-reared birds should be indistinguishable from wild chicks at the same age. Damage feathers will not be replaced until the next natural moult, thought swift can not over winter in captivity and have to be humanely euthanized. However, imping is used by some rehabilitation centres (Haupt 2008), placing undamaged feathers onto the quills of the damaged ones, although is not a routine operation.

Time for release is assumed when the fledgling experiences a change in behaviour and begins to climb the sides of the cage and flap the wings vigorously. It is also necessary that all primaries are sheathed and the wing length is about 165 mm and extends at least 35 mm beyond the tail feathers. Final weights obtained vary, considering optimal fledgling weights from 35-50g. Young are released during the afternoon and in fine weather days. The ideal release site should have a slight slope, be free of birds of prey and with abundance of other wild common swifts.

CONCLUSIONS

We can highlight the importance of establishing the chances of release in order to improve the animal welfare. It would seem that most of the orphans brought to wildlife centres are presumed casualties of natural morbidity caused by exposure, starvation, disease and predation. Should be leave then nature alone? How many hand-raised nestlings survive and make it back in following years? It is hand-rearing a pointless exercise? Are those rescued chicks weak nestlings who have been ejected from the nest because they were to weak to survive anyway? If we are indeed in recover those young, the success depends on the knowledge of the biology of the species. A realistic approach to the problems involved and surely improving rehabilitation protocols and communication between professionals has the potential to make significant advances in the success, and more importantly, in animal welfare.

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