Proper Care, Husbandry, and Breeding Guidelines for the Zebra Finch, Taeniopygia guttata

1. Aim to maintain the zebra finches at typical laboratory temperatures of 20°C–25°C, and ∼40% humidity, with a day–night cycle within the range 12 h : 12 h to 10 h : 14 h.

• In the wild, zebra finches experience considerably wider fluctuations and higher average temperatures than in the laboratory (Zann 1996), meaning that the laboratory might not be ideal for breeding (Schmidt 2010). Of greater concern is the low light intensity in animal facilities designed for rodent husbandry—hence, supplementation with full-spectrum lights is advisable. Day–night light cycles are important as continuous light conditions are known to result in health problems (Snyder et al. 2013).

2. House the finches in wire cages, with a minimum mesh of 12.7 × 15.2 mm, lined with bedding material. There are two main caging options:

• Cage dimensions of 35.6 × 35.6 × 45.7 cm (Fig. 1A,B) are adequate for a single breeding pair or five to six nonbreeding individuals.

  • Minimum cage sizes have not been established for this species (National Research Council [U.S.]. Committee for the Update of the Guide for the Care and Use of Laboratory Animals; National Research Council 2011), but cages that are long are preferred over those that are tall (Bateson and Feenders 2010).

• Alternatively, if control of paternity is not important, house up to eight pairs in a large communal flight cage (244 × 122 × 213 cm).

  • Communal cages can promote health and greater flight strength.

3. Place perches at varying heights throughout the cage and avoid placement above food, water, and grit (Fig. 1B).

4. Provide ad libitum access to food, water, and grit; supplement diet with green leafy vegetables and cooked eggs.

5. Ensure that empty seed husks do not restrict access to food by removing husks daily from seed dispensers.

6. Change drinking water daily, and sterilize water bottles twice weekly.

7. Refresh the bedding every 3 d.

8. (Optional) Provide environmental enrichment.

• i. Deposit natural fibers (grass, yarn, bark), in addition to raw vegetables and sprouts, on the floor of the cage to attract the interest of the finches.

• ii. Place a wide, shallow dish of water on the floor of the cage—this will often be enthusiastically used for bathing.

9. Ideally, house the zebra finches in mixed-sex large-flight cages or aviaries.

• This promotes exercise and allows the birds to interact with, and choose, mating partners—however, these mixed-housing conditions will result in juveniles acquiring songs from multiple males, in addition to their father.

10. Move the birds, as necessary, to separate fighting individuals and sequester breeding pairs.

• Note that individual caging of birds is a source of stress (Bateson and Feenders 2010), and visual contact with other individuals should be maintained if isolation is necessary.

11. To catch birds, turn off the room lights and use a small flashlight for illumination; use a cloth bag or covered cage for transport of the birds.

• The safest way to handle zebra finches is the bander's grip, where the bird's back is held against the palm of the investigator's hand, with the head sticking between the index and middle fingers (Members of the Joint Working Group on Refinement 2001).

12. Use the following criteria to sex zebra finches.

• Distinguish females by their generally tawny-gray color that fades into a whitish breast (see Fig. 1 in The Zebra Finch, Taeniopygia guttata: An Avian Model for Investigating the Neurobiological Basis of Vocal Learning [Mello 2014]).

• Identify males from females by the presence of an orange cheek patch after ∼35 d posthatching (dph).

  • In some color morphs, these cheek patches can be black, white, or even absent.

• Tell young males (∼20 dph; Fig. 1D) from females (Fig. 1C) by the presence of black and white stripes along the throat (Fig. 1D, small arrows), and chestnut markings on the flank (Fig. 1D, large arrow).

• Use molecular methods to sex nestlings by DNA isolation (e.g., from feathers), followed by polymerase chain reaction amplification (Soderstrom et al. 2007).

• Note that only males sing.

13. To breed birds most efficiently, place seven to eight pairs in a large cage (see Step 2) (Bateson and Feenders 2010).

• If strict control over auditory and social input during the posthatching period is required, breeding can also be performed in smaller cages either with visual isolation from other birds or in acoustic isolation within soundproof chambers—it might be necessary to screen the population first to identify birds that will breed well under these conditions.

14. Place nest boxes near the inside top of the cage (Fig. 1B), with a small perch just external to the nest opening.

15. Provide nesting materials on the cage floor and in the nest box—we recommend that coconut husk or hay (cut to a length of 15 cm) be formed into a loose nest and inserted by hand into the nest box.

• Note that allowing a pair to build from scratch can result in poor-quality nests and lost eggs.

16. Monitor the cages for eggs.

• Eggs are laid one per day over 2–7 d. Clutch sizes range from three to eight eggs. Eggs are white and semitranslucent (Fig. 1E) and will have an air pocket visible on the wide end of the egg. Air pockets are 1–2 mm in diameter on the day the eggs are laid and become larger during incubation.

17. After egg-laying starts, remove unused nesting material from the cage floor to prevent further nest building over laid eggs.

• Both parents might continue to add fiber and attend the nest during laying.

18. Monitor the cages during the incubation period. Confirm egg fertility by day 3 of incubation by candeling the eggs to observe the developing embryo.

• Incubation begins when the final egg is laid. Zebra finch eggs require a 14–15 d incubation period, during which both sexes can incubate the eggs, sometimes simultaneously. Females develop a brood patch for the transmission of heat to eggs. Eggs tend to lose 12%–15% of their mass during the incubation period (Rahn and Ar 1974). Humidity levels should be altered (up or down) if the egg mass varies considerably from this range.

19. Monitor the nestlings.

• Chicks, which hatch ∼15–20 d after the eggs are laid, weigh 0.7–1.1 g, are altricial, naked, and have closed eyes (Fig. 1F). Parents will usually brood chicks for 5–6 dph or until the chicks are capable of thermoregulation. By ∼8 dph, plumage is present, eyes are open and chicks become responsive to handling by the investigator. Because the chick's parents deliver food, no special neonatal diet is required, but chick health can benefit from supplementation with vegetables and chicken eggs.

• In the event of nestling abandonment or unavailability of suitable foster nests, juveniles may be reared by hand, see Steps 21–23.

20. Leave the chicks with adults until they are able to feed on their own (∼30–35 dph). Avoid premature weaning as it can result in poor nutrition or death.

• Note that chicks that are left with their parents beyond ∼50 dph can interfere with the success of subsequent clutches.

21. Move chicks to a small incubator set at 30°C–32°C on soft bedding.

22. Feed chicks hand-feeding formula (e.g., ZuPreem) at 2-h intervals from 06.00 to 23.00 h for the first 5 d, and at 3-h intervals after day 5 until the bird is able to feed itself. Deliver the food by syringe until the crop, which is visible through the skin at the base of the throat, appears full.

23. Change bedding between feedings.