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What on earth took Tony to Vladivostock and the Far East of Russia?
The Chinese or Scaly-sided Merganser is a large fish-eating duck which breeds along rivers in ancient forests in Far Eastern Russia, North Korea and north-east China. Their wintering area remains largely unknown, but they have been seen widely dispersed on freshwaters in China in winter, with the majority known from the lower Yangtze River, although there are also reports of small numbers in Japan, South Korea, Taiwan, northern Vietnam, Myanmar and Thailand. It a very striking waterbird, both sexes have shaggy crests and scaled flanks. The adult male has a blackish-green glossy head and neck with a long crest, orange-cream breast and underparts, and dark patterned mantle, while the female has a brownish head and more wispy crest. The species is endangered, numbering less than 4,500 individuals after declines in the 1960s and 1970s due to logging in primary forests along major rivers, but the species is also threatened currently by illegal hunting, entanglement in fishing nets and river pollution.
One of the problems facing the population is an apparent shortage of males. On the breeding grounds, it is common to see single males with 2 females and females paired to young males that have yet to assume full adult plumage. Hence, in contrast to the vast majority of duck species (where males typically outnumber females), it would appear that the boys have a tougher time than the girls for reasons we do not understand.Like most mergansers, the males desert the females early in the breeding season, moving away from the breeding areas to a safe place where they become flightless and replace their wing feathers ready for the coming year. The females do this on the freshwater breeding areas whilst raising their ducklings, but we have no idea where the males go for this function.It may be that whatever is affecting male survival to skew the sex ratio, is operating on their moulting grounds, so it is important to find out where this occurs and whether it is illegal hunting, entanglement in fishing gear or some other factor (such as pollution) that is hitting the males so hard.
Females can be caught in summer at their nest cavities and in artificial nest tubes provided for them under a project funded via the Wildfowl & Wetlands Trust in the UK to Dr Diana Solovieva, a Russian waterfowl biologist who studies the species in the Russian Far East.Males have proved almost impossible to catch, so it was this challenge that took Tony to the Russian Far East in March 2007.Their technique was to stretch strong but fine nets (about 21 m long and 3 m high) across the breeding rivers to try and catch the mergansers as they fly up and down.Because of illegal local shooting the birds tend to fly high most the time, but in the end 3 weeks effort caught 4 mergansers, 2 males and 2 females. Wing feather samples were taken from all the birds to compare with those taken in previous years which have been analysed chemically to show whether they were grown in freshwater or saltwater. The females (as expected) grow their feathers in freshwater, but it appears that the males may do so in saltwater, so this has provided us with vital evidence that we need to search for the secretive males in marine waters during their post breeding moult period. Diana is already preparing a project proposal to search for these elusive moulting areas next year.
The trip was great fun, and in one memorable day off we made a visit to the coast to see 3 Steller’s Sea Eagles, 20 White-tailed Eagles and a host of rare and unusual ducks.It sounds rather mad to travel half way around the world for 3 weeks only to catch 4 ducks (although we saw one other bounce out of the net, one female escaped before could catch her and at least two more punched big holes through our nets!). However, this is a very rare species, they rarely fly low over the water in a manner that makes them easy to catch and they are very difficult to capture under any circumstances, so we were very satisfied with the result.It was also great fun to catch mandarin ducks in the wild as well. Tony was too worried about losing the first bird they caught during extraction from the net to enjoy the first one, but there was a very silly grin on his face for many days afterwards.He was a little disappointed not to at least see tiger tracks in the forest (yes, they occur there too!), but the privilege of being in ancient wild wood that extends over such a vast area was deeply inspiring. He was very impressed by the kindness and warm hospitality of the many Russians he visited and stayed with during the trip and it is this that will linger longest in his memories of the trip.
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