17. Never say die - breeding behaviour in determined Dabchicks Judy New Slent, PO Box 7171, Noorder Paarl, 7623, judynew@iafrica.com On our farm, Slent, on the slopes of the Paardeberg in the Boland of the Western Cape, a pair of Dabchicks were observed for two years since they first moved onto one of our dams in 1999. The dam is triangular in shape, 120 m at the wall and somewhat less at the apex. It is fed in winter by our mountain stream, but relies in summer on the water from our irrigation scheme. Depth is unknown – it has never been empty – but is about 7 m at the deepest part. There is a small island in one corner with poplars which occasionally keel over into the water. There is submerged ‘pond weed’ which the Dabchicks use as nesting material. The pair made the dam their exclusive property and aggressively saw off any other Dabchick that ventured onto the water. They suffered numerous vicissitudes, fatal to their early breeding efforts, but dogged determination eventually produced results. First their nest, with eggs, situated on a low poplar branch, was drowned with an increase in water level in the dam. Later in the year, in summer, when the water level dropped, they tried again, but the level fell so much and so rapidly that the nest was soon high and dry, and the eggs were abandoned. They then built a nest on a fallen poplar tree, but the water level rose in winter and the eggs drowned. I then tied a bale of straw onto the dead poplar, and they happily laid on that. Wind caused waves on the dam, the bale toppled sideways, and again the eggs were sunk. Then I tried a floating hay bale, anchored fore and aft to shoreline trees, but the bale sank after a few weeks and another batch of eggs was gone. Another floating bale, this time with plastic and extra flotation. The bale was ignored, but the water level was again right for the first nest site, in September 2000. One chick hatched, but disappeared a week later – probably taken by a water mongoose. By then we had learned to monitor the water level daily, and kept it constant by means of our outflow pipe. (Our new manager must have though he was working for a pair of loonies: let water out; close outflow; let water out – all for the sake of a couple of birds! Luckily he is adaptable and now enters the spirit of the exercise.) During October 2000, a coot destroyed the poplar-branch site, but the Dabchicks rebuilt it and laid three eggs in November. Two eggs hatched on 3 December 2000. The floating bale, about 10 m from the nest, was used as a resting place and roost by the non-incubating bird. (It floats about 4 cm above water level and is a wonderful platform for even the tiniest chicks as they can hop on and off with ease.) We noticed that they had heaped a pile of weeds and sodden poplar leaves on the bale, and wondered at this, there being an active nest nearby. One parent (the male?) fed chicks on the poplar-branch nest, and the other (the female?) sheltered them under each wing. I was interested to see how meticulous the provider was in alternating left and right-hand side of the nest when he came with food. After three days the chicks were more off the nest than on it. Then the water level rose again, submerging the tree nest. We did not worry about adjusting the level as the family moved happily onto the bale. Now comes the weird part: on 11 December there were suddenly two more tiny chicks swimming with their older siblings, leaping on and off the bale, and on 14 December there was another one! We assume that the three new hatchlings were from a second clutch, which we had failed to noticed despite twice-daily observations, being brooded simultaneously on the bale. The parents worked overtime to keep their five voracious youngsters fed. They were lucky: there were huge schools of tiny bluegill which came through the water scheme as eggs or fingerlings, so every dive produced food for the chicks. I was away for a month over December and January, but monitoring continued with the help of our housesitters. On my return (17 January 2001) the five young were alive and well, adult size, and gradually losing their baby plumage – striped heads disappearing and black caps with a faint peachy tinge below starting to appear. They had become quite independent, keeping to the pond weed on their side of the little dam and feeding voraciously on the myriad little fish. They had to learn to fly quite fast as the male (?) parent gave them a hard time, driving them out of ‘his’ part of the dam and really bullying them quite viciously by diving down with them and harrying them under water too. The reason for the harassment soon became clear: the parents had bred again! (They both seem to be in permanent breeding plumage, their red necks and white spots beside their beaks never disappear.) I got back to find the female brooding again on her tree-branch nest, but then the water level fell disastrously (water pump packed up, so no water was entering dam, and heavy use of water for irrigation) and the nest was suddenly a foot above water level, hanging down disconsolately. However, on 19 January 2001, the female appeared to have chicks under her wings, and a few days later it was confirmed that there were three chicks. So once more the parents were busy feeding their newest brood which, on 27 January 2001, were about 10 days old, and already competent divers. One evening I noticed that the three tiny chicks were so full of food that they all consistently refused the fish that both parents were offering them, and in the end the parents had to eat the fish themselves. The five ‘teenagers’ had, by this time, discovered their voices and, while they were not doing the proper Dabchick ‘laugh’ yet, were giving it a good try. By early February they were calling like adults, and by the middle of the month they were all gone, moving away from the dam one by one. The second batch was raised equally successfully, and parents and offspring all departed by April.

Office Avian Demography Unit
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Document posted: 24-Aug-2001