The amount of some waterbirds seems to be declining, for example, common shelduck, Dalmatian pelican, mallard, falcated duck, red breasted merganser and eastern marsh harrier. I understand that numbers of dalmatian pelican and falcated ducks are decreasing as they are globally threatened, so it’s probably not related to local issues. But common shelduck and mallards are very common in other countries, but them declining in Hong Kong seems odd. However, some woodland species seems to be increasing, such as brown wood owl and bay woodpecker. Why is this trend happening?
A decrease or increase in numbers can have a multitude of reasons. Since you are observing these trends you are probably also the one person who could correlate them to some other observations that random folks from the internet cannot. There might be very specific reasons for your region. Is the water quality decreasing? Are there algal blooms? Are there any changes in the vegetation around water bodies (were they cut down, maybe in breeding season?). Are fish populations decreasing (because there are more people fishing there now, or because of natural reasons)? Are more and more people using drones which scare birds away? Is it even a real thing or could your perception be biased in any way (do you have real data supporting these trends or is it just a belly feeling?)?
For the two woodland species: Are there more dead trees (good for woodpeckers)? Did small rodents multiply heavily in the last couple of years (this has a positive effect on owl populations)?
All of these could be reasons. And there are hundreds more. It’s really hard to give you a definitive answer to your question without knowing the exact location.
What do those water fowl eat? A lack of food could be a problem.
From Korea to Indonesia there is an enormous amount of development taking place in wetland habitats that these (and other wetland birds) rely on, and from China south there is an enormous amount of wetland bird hunting, especially during the fall migratory season.
This, especially if it takes place in seasonally important areas, has major impacts on waterfowl numbers.
We’ve been battling it here in Vietnam, but no matter how much we do it never slows down, if anything it’s been on the rise. Last year we had some really good investigative reporting on it in our area that got the Prime Minister involved, and we are hoping to leverage that into greater protection and enforcement efforts this year.
TRAFFIC has also done a lot of excellent reporting on the bird situation in SE and East Asia, but most of that is focused on songbirds.
actually, it happened over a 10 year period, and common shelduck was one of HK’s most common ducks in Mai Po NR, and it’s very well managed. I don’t think there could be any disturbance.
Is there anything beyond reporting poaching to ENV that we can do here in Vietnam? I’m based in Da Lat and have to report poachers pretty much every week. Hope your quest for increased enforcement up north is successful! Keep up the good work.
A lot of these species breed in eastern Siberia and winter along the East Asian coastline, both of which have been declining drastically over the past few years. Dalmatian Pelican in particular has had its population in East Asia slashed over the past decade, with (IIRC) only ~70 or so remaining, with very little to no net recruitment. into the population.
Many woodland species are gaining back formerly lost ground in Hong Kong and adjacent parts of mainland China due to the (partial) recovery of forested environments in some areas. The species that you mentioned–Bay Woodpecker and Brown Wood-Owl–are notably resident species; migrant taxa such as various flycatchers, leaf warblers, and so forth have seen declines in some areas as their breeding grounds farther north are increasingly affected by climate change. Some “southern” species in mainland China have also seen recent northward pushes–Crested Goshawk comes to mind, along with Red-billed and White-cheeked Starlings–and I wouldn’t be surprised if some species gained ground in Hong Kong by pushing north from southern China and northern Indochina.
Unfortunately, not really.
I run a conservation NGO up here, so we have a bit of local leverage and we work with the National Park, the FPD, and the local DARD branch, and in addition to pushing them on this issue we support them for these activities with financial and equipment support and report activities to the politicians. We also take part in some of the patrols, and we have our own anti-poaching patrols that take place pretty much every other day all year in other parts of the island.
Most other places don’t have those options and resources though, so it’s harder to get the authorities to take action.
Sometimes reaching out to the media serves to kick-start some action.
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