The Scaly-sided Merganser is listed as Endangered, with a global estimated population of about 4660 individuals (HBW).
Such a small number may also mean low genetic diversity – and indeed, this has been shown (source).
The species has high requirements for safety, shelter, and water conditions (source) – not exactly ideal to survive in China.
In fact, one source specifically points out water pollution in China: “The overall health of Scaly-sided Mergansers and their ability to produce offspring seem to be impaired. Exposure to toxic chemicals is a potential factor harming the birds. In particular, rivers in China used by the Scaly-sided Mergansers on their wintering grounds are highly polluted with industrial contaminants.”
What about dams – how do they affect the Scaly-sided Merganser? Apparently, in two ways. These dams reduce the connectivity of the rivers and thus the amount of fish, which harms the birds. On the other hand, the dams increase the water temperature, which the mergansers apparently like – it leads to an increase in their numbers (they would probably even take warm showers given that opportunity).
They also do not move that much – 3.1 km on average (source).
As the Scaly-sided Merganser is not interested in politics, it does not mind breeding in Russia. In fact, 85% of the population breeds there, facilitated by the setup of nest boxes (source).
It is a fish-eating duck – but how many fish does it catch? It seems it depends on the water depth. According to one paper, the mean catch rate was 0.28 fish/minute in shallow waters but only 0.13 fish/minute in deep waters. However, as the fish caught in deeper waters are bigger, the biomass caught per time unit is slightly bigger in deeper waters. Then again, diving in deeper water requires more vigilance and more preparation, so overall, both water depths give similar fish yields – something that may make a scientist conclude that the merganser “is a good example of behavioral flexibility that aligns with expectations of optimal foraging theory”.
One potentially hopeful aspect is that in the Wuyuan area, locals have built bird blinds and earn good money from visiting birders and bird photographers, giving them a strong interest in protecting the birds. However, that does not keep them from happily obliging when the bird photographers ask for a flight shot – one loud clapping, and you have four or five Scaly-sided Mergansers fleeing in panic. People are strange.
Oh, and by the way: I think the female merganser looks a bit like Taylor Swift.
Photo below taken away from the blind – all others taken from the blind.
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