March COOPER, Robin Hybridisation 7 197 1 ]

Robin Hybridisation By ROY P. COOPER, Melbourne Several observations that have been made over the past few years, of the association of the Red-capped Robin. Petroica goodenovii, male, with a Scarlet R obin, P. multicolor, female, recall the record published by F. Watts (1951) of the possible breeding together of these two species, at Heathmont, Victoria, in 1949. Unfortunately, the current observations have not been pub­ lished, and one can no longer be traced. On April 14, 1968, on a property at Lalalty, near Tocumwal, approximately twenty miles north of the Murray River, in New South Wales, F. Fehrer (pers. comm.) watched a Red-capped Robin, male, over a period of twenty minutes, repeatedly attempt to fraternize with a Scarlet Robin, female. On one occasion an offering of food was made by the male bird, when he hopped along the top wire of a fence to where the Scarlet Robin hen was sitting. However, the hen bird was not seen to accept the food, but it flew down to the ground and foraged among the fallen leaves, sticks and grasses. During the period of the observation the Red-capped Robin was observed , for at least nine or ten times. to fly down from one of the many vantage points and repeatedly approach the Scarlet Robin. which continued its search for food. Eventually a Willie Wagtail, Rhipidura leucophrys, chased the Red-capped Robin away from the area, but it did not attack the female Scarlet Robin. After five years of extensive study in this area J. N. Hobbs (1961) found that the earliest date of the arrival of the Scarlet Robin in the Lalalty district was A pril 30, which is 16 days later than the current observation. The second observation was made at Doncaster. approximately four years ago. Unfortunately, no details of this record have been published or are now available, other than the association of a male Red-capped Robin with a female Scarlet R obin. The literature on A ustralian ornithology gives few examples of natural hybridisation among birds in this country. Certain species, particularly finches, parrots, doves and pigeons, have been successfully hybridised in captivity; usually with the choice of mates being limited to the two birds that the aviculturist or the professional ornithologist are trying to breed together. However, the results are usually infertile eggs, or the embryos die in the shells. 1\ small percentage survive and some even successfully mate. Many species of duck, fo r example, not only interbreed fairly freely, but their hybrids are fertile with other species of Anas, so that 'multiple hybrids' involving as many as 5 or 6 species sometimes occur (Thompson, 1964) . 8 COOPER, Robin Hybridisation Bi rd [ Watcher

But this type of mating does not apply to birds in their native surroundings, where, usually, true species continue to breed as species. There are two records of Wood-Swallows, White-browed, Arta­ mus superciliosus, and Masked, A . personatus, breeding together (McGill, 1944, and Barnard , 1944). These species move about and migrate together in large numbers, and also nest in the same area, but even under these circumstances the records are extremely rare. H owever, where there is doubt as to the validity of the species -the two Magpies, Gymnorhina tibicen and G. hypoleuca, (McNamara, 1937), both Red-tipped Pardalotes, Pardalotus sub­ striatus and P. ornatus, (Cooper, 1961), among others- the birds interbreed freely in the zone of their overlap. The statement that the Red-capped Robin " is closely related to the Scarlet Robin" (Officer, 1969) is somewhat misleading. It is no closer related to the Scarlet Robin than to the Flame, Petroica phoenicea, Pink, P. rodinogaster, or the Rose, P. rosea, Robins. The quotation has apparently been taken from the Birds of Western Australia (Serventy & Whittell), wherein it is stated that "The Red-capped Robin is closely related to the Scarlet R obin". This is correct as far as Western A ustralia is concerned, as onl y these two species of red-robins are found in that state. ln other areas all five species are present, and all are equally related. A mong the normal type Muscicapidae, the family under which our robins are grouped, only one hybrid record is listed by A. P. Gray ( 1958), and that is of a species that does not occur in this country. Both Heathmont and Doncaster are some fifteen miles east of Melbourne and , normally, are not frequented by the Red-capped Robin. On the other hand Lalalty is approximately eighty miles west of Albury, on the lowlands of the interior. T he distribution of the Scarlet R obin is stated to be " through New South Wales from the coast across the Dividing R ange to the limits of the western slopes" (Frith, 1969). J. N. Hobbs (1961) confirms the rarity of this species in the area. T his distribution pattern indi­ cates that in each instance one of the birds is near the limit of its range; Red-capped R obin at Heath mont and Doncaster, and Scarlet Robin at Lalalty. · On December 4, 1949, Watts (1951) observed two robins nesting in a messmate, Eucalyptus obliqua, between Heathmont and Bayswater. T he female bird " was broodin g a nest, about 35 to 40 feet from the ground", and she was observed to " fly several times from the nest to the high branches of other trees close by, where she was fed by the male". The male robin was positively id entified as a Red-capped Robin, Petroica goodenovii, but the female bird, although " it certainly appeared to have a fairly bright scarlet breast and a white forehead patch", was not identified as a Scarlet Robin, P. multicolor. Red-capped Robin, male, on edge of the nest in the lemon tree. Pl ate 3 Photo by R oy P . Cooper 10 COOPER, Robin Hybridisation Bird [ Watcher

Six days later a small party visited the area "only to find that the nest had been destroyed". However, they "found that a pair of robins had commenced to build a nest in a messmate nearby at a height of about 25 feet. The female was observed to visit the nest four times with nesting material; the male also went to the nest but did not appear to be carrying any material". The birds were positively identified as a Red-capped Robin, male, and a Scarlet Robin, female. "Another party visited the area on December 17, when the same two birds were, apparently, selecting another nest site. How­ ever, the male bird could not be found on December 26, although some female Scarlet Robins were observed. It has not been seen there since". In concluding his paper Watts states " We do not know whether the female laid eggs, nor, if so, how many, but the fact that she sat on the nest for extended periods after being fed by the male suggests that she was brooding. We also know that a further attempt at nest building was made". In view of the new observations of the association of the Red­ capped Robin and the Scarlet R obin, and the incompleteness of the record published by Watts. the following record of further notes made by Watts and of observations taken from my field notes of the actual breeding of these two species, and the pub­ lishing of the associated photographs, are of interest. During the autumn and spring months of 1950, Watts (pers. comm.) made several visits to the area. However, it was not until November 12, 1950, that he first heard and then saw a male Red­ capped Robin, presumably the same bird. It flew to an overhead wire near the railway line, and it was joined soon after by a female Scarlet Robin, that closely resembled the previous year's mate. This was in an area some 400 yards from where the birds had nested last year. One week later, November 19, R. Ferguson and F. Watts watched both birds for some time, and finally located a partly con­ structed nest in a lemon tree. Ferguson visited the nest on Novem­ ber 24, and it appeared to be completed, but no eggs were in it. The birds were not seen but the male was heard calling from a pine tree. I visited the area, in company with Ferguson, oo December 3, 1950. It was a very hot day; the temperature being 99° in Mel­ bourne but unknown in this area. As we approached the citrus orchard, where the nest was under construction in the lemon tree, we carefully watched for any sign of either robin. Although we exercised every care we finally came to the nesting tree without sighting or hearing either bird. Obtaining a position hom where we could see the nest, we were surprised to find that not only was its construction completed but that a female robin was brooding. Even with the bird sitting on the nest it was obviously a female Scarlet R obin; the small white Scarlet Robin, female, incubating the hybrid eggs Plate 4 Photo by Roy P. Cooper 12 COOPER, Robin Hybridisation Bird Watcher frontal patch was very clear and a scarlet wash on the breast was revealed above the lip of the nest. We had arrived at 10.00 a.m. and, without disturbing the bird, sat in the shade of another lemon tree to watch for the mate. The nesting tree was in the second row of the orchard, and on the near-by boundary there was a row of pine trees. From our position we were able to see the nesting tree and the pines; also to hear any call-note that was uttered. Nothing happened in the next half-hour; the Scarlet Robin continued to sit en the nest, no call was heard from the male and the sun got much hotter. At this time we had not examined the nest and were unaware of its state of construction or its contents. At 10.30 a.m. we slowly walked towards the nest, all the time watching and listening for the male bird. The Scarlet Robin continued to brood until we reached the outer foliage of the tree, and within six feet of the sitting bird. Suddenly. she slipped quietly over the far side of the nest and disappeared among the leaves. As the bird raised up from the nest the full flash of the scarlet colouring on the breast was seen. The nest was placed in the fork of the tree and, in my experience, in a position that was mo re typical of a Red-capped Robin than a Scarlet Robin. Usually, the nest of the Scarlet Robin is a heavier structure than that of the Red··capped Robin, and this one could be regarded as a typical nest of the former species. It was lined with white, yellow, brown and black feathers. and con­ tained twv eggs. The ground colour of these eggs was pale green. which was heavily marked with various shades of brown and grey. These markings predominated in the centre where a distinct zone was formed. They appeared to be heavily zoned eggs of a Sca.rlet Robin. After completing our examination of the nest and eggs we returned quietly to our observation point. Although we had not been able to see the female, due to the foliage on the trees, she must have remained close by as she quickly returned and sat on the nest. However, she did not appear to be able to settle comfortably on the eggs. as she continuously changed her position and gradually turned right round. The heat had now become intense, and although there was some shade from the foliage of the tree, the robin kept her mouth wide open. For the first three-quarters of an hour of our observation the robin brooded the eggs continuously, after allowing for the few minutes that she had left the nest when we investigated the con­ tents. During this period she had not obtained any food, either as a result of her own efforts or through being fed by a male bird. The calls of many birds were heard, but the normal trilling call of the Scarlet Robin, or the clicking notes of the Red-capped March COOPER, Robin Hybridisation 13 1971 ]

Robin were not among them. Neither did we hear the low, soft trilling notes that are uttered by the male bird of each species, when he calls the female from the nest to take the food that he has brought. At 10.45 a.m. we heard the first call of a robin. It came from the direction of the pine trees and it was the normal clicking call of the Red-capped Robin. Only the one call was hea rd and al­ though we listened intently, we did not hear the soft, feeding call. Suddenly a male robin arrived at the nest. There was no mis­ taking the rich colouring of a fully plumaged, breeding male Red­ capped Robin. The difference in the shades of colour on the breasts of the two birds was most noticeable, and the red cap of the male bird contrasted strongly with the white frontal patch of the female Scarlet Robin. Owing to the thick foliage of the lemon tree we had no indi­ cation that the male bird was present until he actually alighted on the limb near the nest. He had a large supply of small insects in his bill, and he fed them to the female as she sat on the nest. After feeding he continued to sit on the branch. Within a few minutes the female bird left the nest and flew away. The male bird sat quietly contemplating the nest, as if deciding whether he would sit on the eggs or otherwise and then, having made up his mind, moved onto the nest and brooded the eggs. This was corroborative evidence of the hybridisation of the Red­ capped and the Scarlet Robins. Although there is no evidence to support such a theory it is possible, although highly improbable, that a male bird of one species could feed the female bird of another species, without actually being a mated, hybridising pair, but it is even more improbable that he would incubate the eggs. The normal behaviour with both the Red-capped and the Scarlet Robins is for the female to build the nest and incubate the eggs. The male bird obtains the food and from a vantage point near the nest calls, with a special low, soft trilling series of notes, the female from the nest. After taking the food she quickly returns to her brooding. For the first few days, after the hatching of the young birds, the female broods continuously and the male bird brings the food to her while she sits on the nest. Some of it is fed to the newly hatched young birds and the remainder swal­ lowed by her. After two to three days both birds feed the young direct, and there are many records of other robins (Cooper. 1969) , of the same species, assisting with the feeding. There are excep­ tions to this behaviour but they are rarely observed or recorded. It was only nine days since the nest was found being built, or possibly completed, so, obviously, the eggs could not have been near the stage of hatching; a period when the male bird may rarely brood, so this pattern did not account for his actions. 14 COOPER, Robin Hybridisation Bird [ Watcher

The male continued to brood for ten minutes and he was then replaced by the Scarlet female; not leaving until she had actually returned. At 11.15 a.m. the Red-capped Robin brought more food to the female, and he then drove her away and brooded the eggs. Changes were again made at 11.23 a.m. and 12.07 p.m. The male bird brought food to the female each time that he returned to the nest. At 12.15 p.m., with the Red-capped Robin still sitting, we walked slowly towards the nest, and I held back some of the limbs of the tree to see if it would be possible to take photographs of this strange mating. The robin did not move from the nest and Ferguson exposed several feet of movie film, from a distance of five feet. However, our presence evidently agitated the female robin and she flew to the nest, quickly drove off the male bird, and settled onto the eggs. More movie film was exposed on this bird. As the bird appeared to be so tame I decided to try and obtain some photographs of this unique mating. Setting the camera on an extended tripod we awaited results. Fortunately, the position of the nest enabled us to open the foliage, with the minimum of interference to the birds. In view of our previous experience with these robins we did not anticipate any trouble in obtaining the photographs, nor did we think that the birds would desert the nest. We had had to return to the car for the camera and equipment, and it was not until 1.30 p.m. that we were ready to take the photos. Within a few minutes the female returned and was photographed. Shortly afterwards the male bird arrived and again we were successful. Throughout the remainder of the afternoon both birds took turns at brooding; no notice being taken of the camera. On one occasion the male arrived and sat on the limb beside the nest, while the female continued to brood. This pattern was reversed an hour later when the female sat on the limb and the male brooded. We finally left the area at 5.30 p.m. On the following Saturday, December 9, we arrived at the nest early in the morning, hoping to find that the eggs had hatched. It would be most interesting to see the result of the Red-capped Robin X Scarlet Robin cross. The birds were not seen or heard as we approached the nest, so we went straight to it. The two eggs were still intact and the nest appeared to be in the same order as previously. We sat quietly and watched for the next hour, but there was no sight or sound of the birds. We examined the nest once more and, although it appeared to be in use, the eggs were very cold, and it was ob­ vious that the birds had deserted. The orchardist had ploughed the orchard during the past few days and on the previous day had hand-cultivated around the March COOPER, Robin Hybridisation 15 1971 ]

base of the nesting tree. Apparently this had been too much for the birds, although the female was seen while the work was being done near the tree. We searched the area and finally located the pair of robins on the opposite side of the orchard. After watching them for approximately two hours the male was seen to pick up a piece of dried grass and fly with it to a lemon tree. Carefully selecting a horizontal fork he placed the grass across it and departed. He did not return within the next half-hour so I examined the tree. It was the only piece of material in the fork and evidently it was to mark the site on which the female was to build another nest. On the 16th I visited the area again, hoping that the second nest would be completed. Apparently the female had different ideas to those of the male and the piece of grass was still lying in the fork, without any further material being added. The birds were not observed. On January 5, 1951, F. Watts (per. comm.) observed a male Red-capped Robin in a Cootamundra Wattle. It made several flights into some eucalypts nearby, where the female Scarlet Robin was feeding. However, both birds were not observed together in the same tree and they gave no indication that they were still a mated pair. Only the male Red-capped Robin was present on the next visit by Watts, on January 16, 1951. There was no sign of the female Scarlet Robin, although the male Red-capped Robin, on one occasion, called softly for about four minutes. Observations on these birds ceased at the above date.

REFERENCES Barnard, H. G., 1944. " Hybrid Wood-Swallows", Einu, 44 : 154. Cooper, Roy P., 1961. " Field Notes on the Nesting of the Red­ tipped Pardalotes", Emu, 61 : 1-6. Cooper, Roy P., 1969. "Multiple Feeding Habits of Wrens", Australian Bird Watcher, 3 : 146. Frith, H. J ., 1969. Birds in the Australian High Country, p341. Sydney. Gray, A. P., 1958. Bird Hybrids, p200. England. Hobbs, J. N., 1961. "The Birds of South-west New South Wales", Emu, 61 : 43. McGill, A. R ., 1944. "Hybridism in Wood-Swallows", Emu, 44 : 153. McNamara, Ellis, 1937. "Magpies Interbreeding", Emu, 36 : 228. Officer, Brig. Hugh R., 1969. Australian Flycatchers, p51. Mel­ bourne. Serventy, D. L., & WhitteiJ, H. M., 1967. Birds of Western Australia, p351 , Perth. Thompson, A. L., 1964. A New Dictionary of Birds, p3 85. London. Watts, F., 1951. "Red-capped Robin east of Melbourne", Emu, 50: 206. .