geometrical perches are greatly inferior to a profusion of natural twigs and branches.) If it is argued that there is danger of relnfection in ‘natural’ as opposed to ‘hygienic’ cages, then the answer is that a bored, frustrated animal will be more liable to sickness than an in- terested, active one. All specimens should be carefully checked for disease and parasites in the zoo hospital before being put on exlu- bition. It is then possible to take the risk of having a more complicated, natural cage environment .

The animals were originally fed once daily but it was soon discovered that if the day’s food was split into two meals, one being given during the morning activity peak and one during the afternoon peak, the best re- sults were obtained - ‘nocturnal’ animals be- ing typically crepuscular rather than truly nocturnal in that they are most active at dawn and dusk rather than at night.

Nesting boxes are simple wooden boxes with entrances for the animals at the side. They are filled with bedding materials and are far larger than the animals would normally need as sleeping cavities in the wild. This is done so that the various species can fashion small interior sleeping places to suit their own particular preferences. A small nesting box forces the animal into a cell-like space that gives it no opportunity to create small side cavities, entrance tunnels, or any other special nest features. We know far too little about the sleeping behaviour of d d animals. It is a platitude to say that they spend half their lives asleep and we frequently imagine that a dark comer is all that is necessary. This is an urn- justified assumption and until we know much more about bed-making and nest-building activities of small mammals, we should pro- vide them with sleeping facilities that give them the widest range of structural possibdi- ties. From this it also follows that their ncsts should be disturbed as little as possible. Such special care may be unnecessary in many cases, but in our ignorance it is the least we can do.

In conclusion, we can say that we have already learnt a great deal from our small temporary nocturnal exhibit and we shall ap- ply our findings when we come to b d d the permanent Small Mammal House. This

method of experimenting during the planning stages of zoo construction cannot be recom- mended too strongly. No guesswork, how- ever inspired, can replace this procedure.

R E F E R E N C E Moms, D. J. (1962): A new approach to the problem of exhibiting small mammals in zoos. Inrer. Z o o Yearb., 3, 14.

THE N E W BIRD H O U S E AT MILWAUKEE ZOO

by G e a r p Speidel Director, Milwaukee County Zoological

Park, Milwaukee County Park Commission, U S A

O N 10th May, 1964, the new bird house at the Milwaukee County Zoological Park was opened to the public.

As with all the exhibits at our new zoo- logical park, a great deal of time and thought went into the planning of the Bird House. The underlying principle was to exhibit birds as far as possible in large groups and to keep small, individual cages to a minimum. We feel that we have accomplished this in a nian- ner that satisfies the requirements of both the birds and the average visitor.

The building is 193 ft. long and IOO ft. wide. It is divided into four halls. By the time the visitor has completed the winding walk through the halls, he has travelled some 43 3 ft. Each step introduces him to some new and exciting feature of bird life.

The visitor enters the bird house across a fieldstone bridge (a stone found in Winconsin) which connects two lagoons at the front of the building. Here, out of doors, live numbers of exotic ducks, geese and swans from all parts of the world. The lagoons are overlooked by an outside terrace which is a part of the nearby restaurant and visitors can enjoy a quiet lunch watching the graceful birds.

Upon entering the budding, the visitor sees a large exhlbit, 45 ft. wide, for penguins. The exhibit is glass-fronted and half-filled with water so that the public can watch the pen- guins swimming and diving underwater. The air inside the exhlbit is filtered and the temperature is kept at a constant S O ~ - S S ~ F .

P E N G U I N H A L L

HUMMINGBIRDS A N D EXOTIC BIRDS

To the left, as the visitor enters the budding, are fourteen small cages for hummingbirds and sunbirds - the glittering gems of bird life. We plan to keep a representative col- lection of hummingbirds since they are very popular with the average zoo visitor. The area is well-stocked with flowering plants and at- tractive vegetation which add greatly to the beauty and well-being of the birds. The par- titions dividing each individual cage are of glass to create the dusion that they are larger than their actual size.

To the right, on entering the bddmg, are fourteen larger cages for exotic species such as Birds-of-Paradise, Bower birds, Umbrella birds, and other rare species.

Continuing his tour, the visitor walks through double doors into the Aquatic Hall. He has just left the Penguin Hall whch has a 10 ft. high darkened acoustic ceiling with no sky- light. He is suddenly confronted with a large room, 50 ft. wide, IOD ft. long and 35 ft. high, with fdl skylights and abundant natural light. Every visitor pauses and seems awe-struck by the first sight of the Aquatic Bird Hall. Only a 14 in. high fence, that blends with the back- ground, separates the visitor from the birds. The naturalistic rodcwork, vegetation and water are so planned that the birds rarely cross the public walks or fly over them except at night-fall, and seldom even then. An in- visible h e has been drawn, of which the visitor is completely unaware, for he appears to be really among the birds. No glass, wire, or other objects obstruct h s vision. A great variety of active birds are exhibited here: gulls, herons, Boatbill herons, storks, pelicans and many kinds of ducks, geese and swans. Several species have already shown signs of nesting.

Along the edges of the public path are seats for the visitor who likes to sit, linger and study the birds. There is plenty of natural vegetation. Water sprays have been placed high in the roof to provide simulated mist or rain falling on the areas set aside for the birds. They are arranged in five rows, any of which can be turned on singly. By experimenting we have observed that this treatment not only

A Q U A T I C HALL

pleases the birds, but also keeps the area and the vegetation clean and fresh. Circulation of air controls the humidity. The roof is almost entirely made of glass and allows a maximum amount of light to promote the growth of vegetation and the well-being ofthe birds.

Air-conditioning prevents the temperature from exceeding 90'~. Without air condition- ing it would be impossible to use this great ex- panse of glass.

PERCHING BIRD HALL

The next exhibit is a large hall for perching birds and a large variety of species are ex- hibited, including bellbirds, mynahs, cocks- of-the-rock, woodpeckers, mot-mots, tan- agers, touracos, quetzals, and many others. As with the other exhibits, everything has been done to make the setting appear as natural as possible. The water pool is not large but it has been attractively laid out and is surrounded with rock-work, trees, flowers and shrubs. There is a waterfall spilling into a small pool and here many birds can be seen bathing or drinking. The planting is slightly denser than in the aquatic section, since many of the birds exhibited live in trees. There are literally hun- dreds of birds: each time a visitor comes to the Perching Bird Hall he sees somethmg new darting in and out of the foliage. Many are already nesting. As in the Aquatic Bird Hall, simulated rain can be provided and there are benches along the public path.

SHORE BIRD HALL

The visitor finally enters the last hall where on one side the shore birds are exhibited in the same type of naturalistic setting as the other halls; and once again there are no barriers be- tween the public and the birds. On the other side of the hall, separated from the public by a small water moat, there is an exhibit of tropical American macaws and Australian cockatoos. In another area of the hall there is a display of finches; while along the western wall there is an exhlbit, 42 ft. long and 4 ft. wide, with glass walls both at the front and at the back. This contains a collection of North American song-birds. Loolung through the glass walls of the exhibit, the visitor can see a number of exotic pheasants in a landscaped enclosure out-of-doors.

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The new Bird House is very popular with thc public. Adults and chddren alike are in- terested in the birds - and even babies in arms seem to be attracted by them, possibly be- cause of their bright colours and constant activity.

Wherever man has been, he has found birds in greater or lesser numbers. W e feel that we have found an ideal way in which to exhibit them.

‘WALK-THROUGH’ B I R D AVIARIES

A T F R A N K F U R T ZOO by Clrrisroph Srherpner

Scientific Assistant, Zoologischer Garten Frankfurt/Main, Germany

I N August 1963 the second part of the bird section, the ‘bird thicket’ was completed at Frankfurt Zoo. It is an outdoor enclosure, mainly occupied by species of birds that are hardy enough to stay outside during the win- ter, and has a surface area ofabout 1,000 sq. m. It was built at a cost of almost z00,ooo DM. A special feature of the new enclosure is that the public is allowed to go into the aviary with the birds. Thcre are no bars to obstruct the view or spoil photographs. Bushes, trees and thick ground Vegetation provide the birds with many hiding places, but they grew used to people so quickly that they can be observed from a very close distance. The entire en- closure is surroimded by high bushes. Thus the netting of the flight aviarics completely disappears behmd t h s natural screen and the greenness of the bird thicket merges ad- mirably with the surrounding vegetation of the zoo.

The new enclosure consists of twelve flight aviaries, of which two are separated from the public section by netting and high bushes. These protected areas are for acclimatization and for breeding the more sensitive species. The public footpath runs along the front part of the rest of the aviaries. It is separated from the birds’ actual flight and ground areas by low boundary marks of various kinds. The winding path and its varying breadth does away with the dreary impression o f a long

line of cages. Another attraction is the varied way in which the flight aviaries have been set

The rear boundary of the aviaries is formed by the pheasant house. It is a brick building with a roof, that projects above the outside enclosure for one metre: thus there is a dry, outside shelter for the birds. The house con- sists of fourteen rooms, one for each aviary and two each for the acclimatization aviaries. At the back of each individual room there is a solid, lockable door with a viewing panel. In the same door frame there is a second door of wire netting and when this is opened, the inner part of the room is shut off. This arrangement makes it possible to shut the birds up in their sleeping quartcrs when major work has to be done in the aviaries. O n the other hand, in the summer, they can be shut out of their sleeping quarters so that they do not hide themselves during the day in a place where they are invisible to the public. The rooms are lit by a large pane of wire glass, facing the outside enclosure. The glass is frosted so that the birds do not fly into it.

Only the first four rooms are connected with thc central heating system of the bird house. Hcre, less hardy species, such as the Argus phcasant, Argusiantis, the African White- brcasted guinea fowl, Agelaster, the Goliath heron, Ardea yoliath, and the kagus, Rhyno- detosjubatus , spend the winter. In the other flight aviaries, the perching and sleeping places are heated as required by electric radiators. Thc keepers enter thc enclosure through the indoor rooms, so that the public is not disturbed by cleaning operations. Be- hind the shelters is the service path with water connections and storage space for sand, dec- orative stone, etc. The food for the inhabitants of the bird thicket is prepared in tlic kitchen of the bird house.

The outside enclosure consists of a galva- nized tubular structure, 2.40 m. high on a low concrete base. The wire netting (the meshes are OX 20 mm. wide) is galvanized and coated with plastic. In some flight aviaries, which may one day be occupied by small parrots, the netting is made out of copper wire. In the barred partitions between the individual flight aviaries, immediately adjoin- ing the shelter, each aviary has one large

out.

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