9 Birds – an introduction

Introduction

Birds such as parrots and canaries have been kept as pets for many centuries, for their beauty, song and mimicry. Raptors are more usually kept for hunting. It is impossible to provide details of all species (there are around 10 000), but the rudimentary principles of captive avian husbandry will be covered. This chapter will also outline clinical assessment and elementary investigations.

Taxonomy

Taxonomic classification of birds in the superorder Neognathae is given in Table 9.1.

Table 9.1 Taxonomic classification of birds in the superorder Neognathae*

Biology

Basic internal anatomy for birds-including gastrointestinal, respiratory and cardiovascular – is given in Figs 9.1–9.3.

Figure 9.1 Ventro-dorsal view of internal organs.

Figure 9.2 Lateral view of internal organs.

Figure 9.3 Air sacs in birds.

Psittaciformes

African grey parrot (Psittacus erithacus)

These parrots originate from sub-Saharan Africa, and are commonly seen as pet birds. They often respond to attention and stimulation by forming a close bond with owners. Cages marketed for parrots are often too small for anything more than temporary accommodation at night. Ideally, an outdoor aviary should be provided to permit free flight. A sheltered area is necessary for sleeping and to protect the bird from adverse weather conditions. If an outdoor enclosure is not a viable option, exercise may be provided in a secure room indoors. The enclosure should be made of non-toxic materials, avoiding heavy metals such as zinc and lead, and sited away from sources of toxic fumes such as polytetrafluoroethylene (PTFE, from heated non-stick cooking materials).

Various perches should be provided in the enclosure, and toys added (and changed regularly to retain interest). Parrots are sociable, and should be paired with a conspecific if possible. If parrots are left alone, a radio can be switched on to provide some stimulation. Full spectrum UV lighting should be provided for African greys housed indoors, to help prevent behavioural problems and hypocalcaemia.

Although free-ranging birds eat a large amount of nuts and seeds, over-feeding of these foodstuffs in captivity results in malnutrition due to differing energy requirements (lower in captive animals). It is advisable to feed a proprietary pelleted diet, supplemented with fresh fruits and vegetables (10% of the diet), and some sprouted pulses (Box 9.1). Grit may help with digestion. Vitamin and mineral supplements may be additionally required, particularly for breeding birds (Box 9.2). Fresh water should be provided in a bowl for drinking; many birds also appreciate a shallow water container for bathing.

BOX 9.2 Hypocalcaemia

This is extremely common in African grey parrots. It is often associated with malnutrition and a lack of access to UV light. Clinical signs typically include ataxia and seizures.

BOX 9.1 Toxic foods for parrots

These include avocado, caffeine (in tea or coffee), alcohol, chocolate and salty foods.

Budgerigar (Melopsittacus undulatus) and cockatiel (Nymphicus hollandicus)

These two species both originate from Australia. Budgies congregate in large flocks over semi-arid plains. Cockatiels are small members of the cockatoo family, and are also a social species.

In captivity, both are ideally housed in an outdoor aviary enabling flight. It should be made of strong wire mesh, with a sheltered sleeping area. As with all outdoor enclosures, construction should be solid to prevent predator access, and a double entry door is advisable to prevent escapes. If housed indoors, accommodation should permit exercise through daily flight. Perches and toys are provided as for other parrots.

Adult male budgerigars of most colour varieties have a blue cere while adult females have a pink/brown cere. Adult male cockatiels have bright red/orange cheek patches, and females retain horizontal bars on their tails; some features of sexual dimorphism will not be visible in certain varieties (such as cheek patches in the lutino).

Captive diets may include small seed mixes, although commercial formulated pellets are better balanced. Fresh green food (e.g. chickweed, dandelion or lettuce leaves), small amounts of fruit, and cuttlefish bone should be provided. Vitamin and mineral supplementation is advised if the bird is on a seed diet (Box 9.3).

BOX 9.3 Iodine deficiency

This is common in budgerigars fed on all seed diets, resulting in thyroid pathology. Providing an iodine supplement, e.g. an iodine block, prevents the condition.

Blue-and-yellow macaw (Ara ararauna)

This bird originates from South and Central America. Its large size (up to 1.3 kg in weight) means accommodation should also be spacious. Providing there is sufficient interaction, macaws will bond closely to their owners. Dietary requirements are similar to the African grey parrot.

Passeriformes

Falconiformes

This order includes hawks, falcons, eagles and vultures. These species are chiefly diurnal. Most are solitary except during the breeding season, although Harris’ hawks (Parabuteo unicinctus) are gregarious. Raptors may be kept for hunting, demonstration flying, clearing airfields and rubbish dumps of other birds, pest control and breeding for conservation or commercial reasons.

Birds are either kept tethered or housed in an aviary (Box 9.4). Tethered birds are attached to a perch by a leash (Box 9.5) during the flying season (typically winter for hunting and summer for birds used in public demonstrations), and normally moved to an aviary during the close season for moulting. Some birds may be ‘free-lofted’ (being housed in and flown from aviaries), in particular vultures that may find tethering stressful. Substrates in enclosures vary from bare earth to gravel to bark chip; all should be hygienically maintained to reduce the risk of disease.

BOX 9.4 Perches for raptors

• Bow perches are used for hawks, buzzards and eagles.

• Falcons are maintained on block perches.