IS0 B R E E D I N G

at two years and there are records of zo-year-old REFERENCE DELACOUR, J. & AMADON, D. (1973): CUfUSSOWS and related birds. New York: American Museum of Natural History.

Manuscript submitted 16 March 1976

birds still producing.

PRODUCT MENTIONED I N THE TEXT Coop 28% Protein Poultry Crumbles: United Producers and Consumers Cc-operative, 20th Street and Jackson, Phoenix, Arizona 85001, USA.

The breeding and maintenance of some northern European waders

a t Helsinki Zoo Charadrii [Plate 361

ILKKA KOIVISTO Director, Helsinki Zoo, SF-00570 Helsinki 57, Finland

Waders, or shore-birds, are often displayed in large mixed-species aviaries, although it is not unusual in many collections to find special wader enclosures. In view of their wide prevalence in zoos, it is surprising how little has been published concerning their maintenance and breeding.

Breeding at Helsinki Zoo began in 1969 with the collection of eggs of the redshank Tringa totnnus and tumstone Arenaria interpres from the islands lying east of Hels&. These first two clutches of four eggs each-a normal clutch size for waders -were artificially incubated at a temperature and humidity similar to that used for pheasant eggs. They all hatched and the chicks were successfully reared. For the first week the hatchhgs were kept in a cage measuring 0.5 m2, room temperature being maintained at or above 2 2 O c by means of an infira-red heater. Subsequently they were moved to a larger z.om2 cage and the heater was used only at night; during the daytime, whenever the weather was warm and sunny enough, they were put outdoors. Starting diet consisted of ants' eggs, chopped white of egg, boiled and minced fish and shrimp, and a commercial insectivorous bird food. No growth data was collected at this time.

This procedure has since been used to rear a number of wader species, both bred in the zoo and originating from the wild, including the

Common sandpiper Actitis hypoleucos, Little ringed plover Charadrius dubius and ruff Phifo- machus pugnax. In addition to collecting eggs, several young birds were acquired by capture and a few injured or starving specimens were rescued and brought to the zoo by members of the public. The captures, which took place in August 1971 and I972 in the vicinity of Helsinki and on the west coast of Fdand, were by methods used by licenced bird ringers, or by net and trap.

Lapwing Vanellus vanellus Golden plover Pluvialis apricaria Ringed plover Charadrius hiaticula Little ringed plover Charadrius dubius Spotted redshank Tringa erythropus Redshank Tringa totanus Greenshank Tringa nebularia Green sandpiper Tringa ochropus Wood sandpiper Tringa glareola Common sandpiper Actitis hypoleucos Turnstone Arenaria interpres Woodcock Scolopax rusticola Snipe Gallinago gallinago Knot Calidris canufus Little stint Calidris temminckii D& Calidris alpina Curlew sandpiper Calidris ferruginea RUfF Philomachus pugnax

Table I. Wader species kept at Helsinki Zoo.

BREEDING 151

H O U S I N G A N D DIET

Two of our former tropical birdhouses have been remodelled to accommodate waders. We com- bined several small cages, so that in the smaller of the two houses each of the three units consists of a 6 x 5 m outside enclosure, with two indoor cages each measuring 3x25 m. The outer enclosure is separated from the public by a 6 mm thick acryllic wall made of 2.5 x 1-7 m sheets, The public is not allowed inside the buildings.

The larger house was adapted especially to suit the needs ofruffs. Here the area of the outside enclosure is IZX 6 m and the three inner en- closures completing the unit are each 4~ 3 m. In both houses there are water ponds in all the outdoor enclosures and in alternate indoor cages. Built of fibreglass and cement, they cover about one-fifth of the floor space and are several centimetres in depth. We have found that moss, dampened slightly to eliminate dust, forms the most suitable indoor substrate; sand, which we also tried, tended to cut the birds’ feet and cause infection. The ground outside is covered with a layer of coarse-grained sand, topped with a mixture of soil and finer-grained sand. Local species of Festtica, Calamagrostis, Poa, Alnus and S a f i x planted in these outer enclosures have thrived and spread.

The adult diet consists of hard-boiled, chopped eggs, fish and meat, small shrimps, wheat germ, a commercial insectivorous bird food, diced apple and lettuce. This is supplemented with a vitamin/ mineral preparation. While they are still growing, the young also receive mealworms and ants’ eggs.

During the coldest months (January-March), the birds are kept permanently indoors, but once the snow has gone they are able to stay outside the whole time. In late autumn and early spring they can go outdoors whenever the weather permits.

The woodcock Scolopax rusticola and snipe Gallinago gallinago are two of the most difficult species to keep in captivity. Both require separate and undisturbed enclosures, and the manner of feeding must be as close as possible to natural. Their diet consists mainly of worms which they can dig themselves from soft mud. Small waders such as Calidris spp should be kept apart from larger birds as their size is a distinct disadvantage in the competition for food; in weakening them,

this may make them more susceptible to infec- tions, such as Salmonella.

Tringa spp, on the other hand, can safely be housed with other species, even with the highly aggressive sandpiper; and the Ringed Charadriur hiaticula and Little ringed plovers, despite their small size, can be kept together with ruE Of course, it is preferable to keep them on their own. Species such as ruff, lapwing Vanellus vanelhis, Golden plover Pluvialis apricaria and turnstone are more easily manageable and can be mixed without difficulty, except during the nesting period when - apart from the ruffs - they tend to be quite aggressive. In the wild they mount guard over a large territory and fight vigorously against any trespasser. The best solution is to house each nesting pair in a separate enclosure. Being limited by space, we have lost several birds because of interspecific conflicts, the most belligerant in our experience being the turnstone and Common sandpiper.

In general, to keep waders in captivity requires a considerable number of enclosures - ideally, one for each nesting pair. The intermingling of species should be avoided during nesting time. Ruff are an exception, and in our largest enclosure we house over 3 0 individuals, half of them &’, with no trouble whatsoever. Their social display and comparatively small courting territories distinguish them in marked degree from their extremely aggressive relatives. The highly developed display has tempered fighting between $6 to the level of mere ‘bluff’, and in doing so, has rendered it harmless (Plate 36).

BREEDING The following species have been successfully bred at Helsinki. Had we been in a position to provide more individual enclosures, the record would, of course, have been more extensive.

Little ringed plover: In the spring of 1974 wc housed four (2.2) two-year-old Little ringed plovers together with one Ringed plover and four d& Calidrir alpina. A breeding pair formed, and owing to their somewhat aggressive behaviour towards their two conspecifics, the latter had to be removed. The Ringed plover was also taken out. The first egg was laid on 7 May and the second a day later, whereupon the nest was abandoned. The eggs were artificially

152 B R E E D I N G

incubated and the young, which hatched in 22

days, were successfully hand-reared. The second clutch of four was incubated by the parents, beginning 27 May, and all but one hatched on 20 June; these chicks were reared by the birds themselves.

The following spring there were eight of the species in the same enclosure but again, when the original pair started nesting, the rest had to be removed. A clutch of four eggs all hatched on 3 0 May 1975 and were reared by the parents. A second pair formed amongst the six unmated plovers - now living with the ruffs - and pro- duced two eggs, one of which hatched on 4 June; this, too, was reared successfully. By aiitunui 1975 we had over ten Little ringed plovers and six were subsequently sent to London Zoo.

Sported rcddiarik: Four Spotted rcdshanks Trirya erytkropirs that had been hand-reared in 1969 from eggs collectcd from the wild began courting in the spring of 1972, but no nesting behaviour was observed. A pair formed thc following spring and became so aggressive towards the other two birds that these had to be removed. A nest was built in duck grass and eggs were laid on 22, 25, 27, 29 and 30 May; the first was brokcn within a few days and two further eggs cracked during incubation. The reinaining two hatched on 21 June. The presence of a few Green sand- pipers T. o c l i r t p s and Wood sandpipers T. ~Iareoln did not disturb the nesting.

The pair bred again in spring 1974. The first clutch was laid 3-6 June, but the nest was abandoned and the cggs broken. Between 15-20 June the pair laid a new clutch and started incubating. Again the eggs were broken one by one - according to the keepers' observations, by the birds themselves. It may be significant that at the time of the first clutch, a turnstone had also been housed in this enclosure; it had been removed before the second clutch was laid. Turnstones in the wild are said to eat the eggs of other species, especially of terns Steriiirrae (Bergman, 1946). As one of the breeding pair died in the winter of 1974-75, there was no nesting that spring.

Coitimori satidpiper: Four Common sandpiper eggs were collected and incubated in 1970 and in spring 1973 two of the resulting birds formed a

pair. They had alrcady begun courting while still wintering indoors and, as with the species described above, their aggression necessitated the removal of the unniated two. A nest being built in a corner of the indoor enclosure, between ro-16 May four eggs were laid; three hatched on 6 June and were reared by the parents. Several birds were lost from Salriioriella and a new breeding pair has so far failed to form.

Ti in rs to r ie : Several turnstones were hand-reared in 1969 and every subsequent spring belligerent and noisy courting behaviour was observed, so much so that in one of these skirmishes a 8 was lost. Not only the 85, but even the single 9, was aggressive and occasionally had to be removed. Notwithstanding such activity, pairing had failed to evolve until the spring of 1975, when, with only two 88 and a 9 together in the en- closure, courting grew less intensc and a pair began to form. Removal of the surplus 6, strangely enough, almost interrupted the court- ship and not until he was transferred to an adjacent cage did the pair resume and build their nest. Thrce of the four eggs laid hatched on II June and two of the chicks were raised.

Ri@ The ruff colony in spring 1972 consisted of 12 35 and ten 99, housed in one small enclosure. All the 36, which with the exception of two individuals had been born the previous year, achieved breeding plumage; the 99 showed no sexual activity.

On 24 May 1973, when the &' had already been displaying for two months, the birds were moved into a larger enclosure. Copulation was observed on 4 and 5 June, it being noted that the ?? tended to mate between 1700-1900 hours; unobscrved mating may, however, have taken place in the early morning. Beginning on 7 June, four of the 99 started laying (four eggs each), but only one completed incubation. Except for the few that were artificially incubated, the remaining eggs were all broken. The chicks that hatched in the enclosure were successfully reared, as were most of the hand-reared ones, although several of the latter suffered a softening of the bones which required treatment with vitamin D.

In 1974 spring came early and the ruffs were released outdoors by mid-March. As in previous years, copulation took place at the end of May

BREEDING ' 5 3

and beginning June. Egg-laying started 29 May and by 2 June the first $' had begun to incubate a clutch of four. Of the 11 $?? altogether, only four lnid and, as before, some of the eggs disappeared. Five chicks were hatched and reared. Another early spring in 197s meant that the 88, released once more in mid-March, were by the end of the month already busy displaying. The first $? began laying in the outer enclosure on 14 May, with three more eggs being produced on 16-18 May, but again they began to disappear during incubation and w i t h ten days all four had gone from the nest. She laid again on 27 and 28 May and then, after we had arranged nesting sites protected by straw in the inner cnclosure, she laid her first egg here on 29 May. Although this disappeared, a further three (the last laid on 4 Junc) were incubated. At the same time, several other 99 laid in the outside en- closure, but these eggs were either smashed or disappeared at the same rate as before. However, another nest arranged indoors induced a second $' to lay there and to begin incubating the four eggs.

In trying to uncover the reasons for the break- ages, we observed one of the ?$? in the act of breaking and eating an egg, and after h s all

unbroken eggs ( I 8 altogether) were removed for artificial incubation; 12 of them hatched.

The turnstones and Spotted redshanks also display a tendency to eat eggs, perhaps because of some nutritional deficiency or possibly by reason of a behavioural disorder. Wadcrs in general tend to peck at eggs that are not their own. As already described, none of this behaviour occurred when a ruff $' was isolated in an inner enclosure at the time when she began to lay.

A U T H O R ' S NOTE In the 1976 season the ruffs were the only wader species to breed. About 40 eggs were laid but again many were eaten, and only 12 were reared - this time by the 99.

ACKNOWLBDGEMENTS I am very grateful for the valuable assistance and co-operation given by keepers Mrs Senja Hukkanen, Mrs R a j a Kettunen and Mrs Mirja Pursiainen.

REFERENCES BERGMAN, G . (1946): Der Steinwiltzer, Arenaria i. intcrpres (L.), in seiner Beziehung zur Umwelt. Acfa rool.fenr1. 47: 1-151.

Manuscript submitted 10 May 1976

Inca terns Larostrrna iwca [Plates 37 & 381

at the New York Zoological Park D O N A L D B R U N I N G & M A R Y LOU CLARE New York Zoological Pork (Bmrzs Zoo), New York Zoological Society, New York i04G0, USA

The first Inca tern Lorosterria inca acquired by the New York Zoological Park arrived in April 1924, having been captured in the propeller shaft of a ship (Crandall, 1956). More than 30 years were to pass before the species was again ehbited, and not until 1964, with the opening of the new Aquatic Bird House, did the ten birds which then comprised the colony have a suitable place in which to breed.

In that year the first of six surviving Inca tern chicks hatched in the Sea Cliff exhibit, a display

measuring about 9 x 3 m, with a fibreglass cliff and a 2 m deep pool covering almost two-thirds of the exhibit area. Mirrors at each end give the illusion of a much larger size. The entire e h b i t is air-conditioned and artificially lighted. During 1965, a total of seven chicks were reared and in the next three years an average of six young were raised each year.

In 1968 the terns had to be removed from the Sea Cliff as their breeding activity prevented the colony of Tufted puffins Lunda cirrkata, which