o 0> Q) i:5 c CO (f) '0 m>- Breeding management of .(3 o (f) ro .5>u o Four Tanager Species <5 o N @ c o in a Mixed Species Exhibit .~ CO ~ c o a: at the San Diego Zoo >- .D o (5 .r; Cl.. byAmy Kendall and Ed Lewins San Diego, California ~ ;2 o>­ The K.C. Lint Hummingbird Aviary walk on one side of the enclosure c;. .0 0 at the San Diego Zoo offers the visitors which provides visitor viewing. (5 a close up view of a wide variety of Except for the summer months, three a: small colorful birds in a lushly planted quarters of the top is covered with a environment. Although the concentra­ translucent plastic tarp to provide tion of 27 species of birds coexist shelter from inclement weather. peacefully most of the year, the breed­ The enclosure contains a wide vari­ ing season presents many challenges ety of tropical plants which provide for optimal management. During this the birds with a naturalistic habitat. period, competition for territories, The flora of the enclosure includes nests, and speciality food items Bromeliad spp., Fuschia hybrids, changes the population dynamics of Impatiens hybrids, fern spp., and the enclosed environment. By modify­ palm spp., along with several species ing our management techniques, we of flowering vines (Passiflora mori- have improved the breeding success folia, P. incense, Thunbergia mysor­ of four species of tanagers: Turquoise ensis,) and a mandavilla. The wide Tanager (Tangara mexicana), Silver­ selection of tropical plants provides throated Tanager (Tangara icteroce­ year round blossoms for visitor appeal phala), Spangle-cheeked Tanager and environmental enrichment for the (Tangara dowii) and Golden-masked birds. Tanager (Tangara larvata). Their diet consists of a soft fruit mix ~ In addition to the tangara species, of apples, pears, papaya, grapes, ;2 other tanagers in the aviary include cooked rice and Ziegler low iron pel- ~ a: Yellow-throated Euphonia (Euphonia lets, large pieces of avocado, banana, £ hirundinacea), and Golden-browed papaya, apple, orange, soaked fig, .§ Chlorophonia (Chlorophonia OCCipi­ and chopped greens. Small crocks a: talis). Also present are several species with soaked monkey biscuits and of finch (Tiaris, Sporophila spp.), Nekton Lory (Nekton) are placed in plover (Pluvianus spp.), Pink-eared the pan. A finch seed mix and meal­ Ducks (Malachorhynchus membran­ worms (Tenebrio molitor) are also aceus), two species of sunbirds (Nec­ provided. Blair's Superpreen is sprin­ tarinia spp.), and eight species of kled on the soft food for a vitamin and hummingbirds (Amazilia spp., Myrtis, n1ineral supplement and Roxanthin as Anthracothorax, Campylopterus, Met­ a color agent. allura and Rhodopsis). Nektar Plus (Nekton) is provided in The Hummingbird Aviary is a walk­ the morning throughout the aviary in through, open-air enclosure measur­ hummingbird bottles (Planit Enter­ ing 64 feet by 24 feet by 16 feet 5 prises). In the afternoon, the nectar is inches. The dome framework is cov­ replaced with sugar water in a four ered by 1/2 inch by 1 inch 12 gauge part water to one part sugar ratio, wire mesh. There is a covered side- because the Nektar tends to spoil Silver-throated Tanagerfeedingyoungster. 60 January / February 1994 more quickly in warm weather. Nek­ o 0> Q) ton Bio (Nekton) is added as a vitamin (5 C and mineral supplement. The excep­ «I C/) tion to this is in cooler weather when (; Nektar Plus is given both morning and m:>0- "[j afternoon. Live fruit flies (Drosophila o C/) melanogaster)J wax moth larvae (Gal­ (ij () '0 leria mellanella) and spiders (Phocus o phalangoiodes) are distributed three oo N to four times a day. g c o A variety of small open cup and C/) .~ (ij domed wicker nests are placed at a (!) c variety of heights within the aviary. o a: Raw packing cotten, sphagnum moss, :>0­ .0 Spanish moss, spider webs, burlap oC/) (5 strands and floss silk seed pods (Chor­ .c. isia speciosa) are provided throughout Q.. the exhibit for nest building. The birds also use leaf litter occurring naturally on the ground. Both the female and male of all four Spangle-cheeked Tanager adult. Tangara species in the aviary have been observed to gather and carry nesting material. With the exception of the Spangle-cheeked Tanager, which has been observed in nest- building, it has not been determined if the males actually help with the build­ ing or simply provide material to the female. The tanagers appear to exhibit a species specific pattern to the nest type and location within the aviary. Despite the provision ofopen baskets, the Silver-throated Tanagers build their own shallow, open cup nest, usually at mid level in the aviary, under plant leaves. The Spangle­ cheeked Tanagers consistently bur­ row a nest in the sphagnum moss of fuschia planters hanging two to three Turquoise Tanagerchicksfive weeks ofage. feet from the ceiling. The sides are built up under the foliage creating a deep, open cup nest. Turquoise and Golden-masked Tanagers add materi­ als to the open nest cups provided. Mosses and cotton are added by the birds to the sides creating a domed nest with a side entrance. These two species nested within inches of the roof. After completion of the nests, the pairs of tanagers have been observed to'exhibit more intense courtship behavior, consisting of mate feeding, wing fluttering and bowing. Within a couple of days, the first egg is laid in the nest, followed by a second the next day. The eggs of all four species are off-white with brown speckles concentrated at the broad end of the egg. Female tanagers are solely responsible for incubation and leave Turquoise Tanager adult. afa WATCHBIRD 61 the nest for only short periods of time. to 14 days. chicks are stable, and eating on their The males of the four species have no The greatest risk ofdeath or injury to own for a period ofone to two weeks, direct role in incubation but are in a young tanager in the Hummingbird the parents are returned to the main close attendance feeding the female at Aviary is during the fledgling period. aviary. The chicks, however, remain the nest. Incubation is 14 days begin­ Curiosity and aggression from other off exhibit for several months so that ning after the clutch is complete. birds make it difficult for the parents they may become physically mature. Wax moth larvae is the primary food to simultaneously feed and protect the Care must be taken when releasing during the nestling and weaning per­ young. Hypothermia and drowning is the parent birds back into the aviary iod. The larvae are dusted with cal­ a problem due to the pool and the because aggression primarily among cium carbonate and Blair's Super­ stream. It can be difficult for the par­ tangara species can be especially high preen. Both parents feed the young. ents to locate the youngsters because upon reintroduction. To alleviate this Spangle-cheeked Tanagers and Silver­ of the dense foliage and sometimes problem, anytime tanagers are intro­ throated Tanagers collect spiders high ambient noise levels. Additional duced into an aviary where another placed in the aviary. Spangle-cheeked dangers occur if the chicks fledge into pair of tanagers is already housed, the Tanagers have been observed to also the visitor pathway. new occupants are "howdied" into hawk and glean fruit flies when feed­ To minimize danger and protect the the aviary. This is a procedure where ing chicks. Nectar and pieces of chicks from injury or death, a fledge the birds are placed within the aviary, soaked monkey biscuit are also management protocol has been in a small utility cage as described favored. When the chicks are about 10 develped at the San Diego Zoo over above, for a period of four to seven days of age, the parents begin to feed the last two seasons. The protocol days. This allows all the birds to avocado, banana and papaya. Close to affords safety for the tanager families become familiar with one another. fledging, both parents seem to and thus maximizes chick survival. The howdy cage door is opened and encourage the chicks to leave the nest Two to four days before the the birds are allowed to leave on their by carrying wax moth larvae and expected fledge, certain precautions own. After reintroduction to the aviary vocalizing from nearby perches. are implemented. The waterfall is it is usually only a few days before Chicks of the four species fledge at 12 turned off, eliminating the stream run­ courtship and nesting begin again. ning through the enclosure. Depend­ Through the development of this ing on the location of the nest, the protocol, the hatch to independence pond mayor may not be drained. A survivability of the tanager species in natural barrier of potted bamboo the Hummingbird Aviary is 85% for Deadline Schedule plants is placed in the walkway under the 1991 and 1992 seasons. We hope or near the nest to encourage the that with further refinement of this chicks not to fledge into the walkway management technique, survivability Mar I Apr'94 Feb. 1 - editorial copy and to protect the nest from visitors. will continue to increase. Feb. 15 -displayADS After these precautions have been taken, careful observations are made Acknowledgement in order to catch the fledglings as soon Special thanks to Wayne Schulenburg for his May I June '94 tehnical advice, encouragement and support, and Featuring as they leave the nest. to Jerry Gallenberger for his help with the birds CONURES. BROTOGERIS. The parents work together to tend during this project. FORPUS the newly fledged young, which Bibliography April 1 - editorial copy makes it easy for the keepers to locate Isler, Morton L., and Isler.