Satellite Tracking study of duck wintering in HK 衛星追縱港渡冬野鴨

It is interesting that one of the birds has now left Hong Kong, and has moved across to the western side of the Pearl River Delta. It seems to be using an area of agriculture and fishponds near Zhongshan. The other birds are all still in the Deep Bay area. There is no sign yet of northward migration, which should start sometime in the next few weeks.


Very good news - four of the male Pintail from Hong Kong have set off on migration in the last 2-3 days. These birds have now stopped at the Yantgze estuary near Shanghai. It will be interesting to see where they head now, and to see when other birds start to move.


So far 15 of the duck are confirmed to have departed on migration. Staging sites include the Yangtze estuary near Shanghai, Lianyungang on the coast of the Yellow Sea (in Jiangsu province) and sites on the cost of both North and South Korea.

Of the remaining birds, 3 are still in HK, 1 is on the western side of the Pearl River and 1 is at Haifeng. 4 tags have not sent a signal since at least February but we hope these will start again - the signals are apparently difficult to detect if the birds is in cover or in built-up areas.

It's certainly interesting to follow where these birds go.


The HK ducks seem to now be approaching their final destinations on the breeding grounds. There are currently birds in NE China, Siberia, Eastern Mongolia and South Korea.  It has been surprising that the northward migration has taken so long - the first birds left HK in late February and are still not on their breeding grounds, after long stop-overs around the Yellow Sea.  Most birds have followed an extreme easterly route, but some are now starting to track slightly more west. Unfortunately, however, some tags have been lost - it is not known what has happened to these birds.

Take a look at the current distribution of ducks on the project website:
or on the WWF-HK website:


The results from last winter showed some interesting results: birds were very mobile around Hong Kong (and elsewhere in southern Guangdong!) in winter, and were often associating together while in HK. Many birds seemed to leave HK at the same time (possibly in a single flock) and fly to important stopover sites around the Yellow Sea; some stayed in this area (in Korea) for a surprisingly long time. They also ended up in a wide range of locations, with birds spread from the deserts of Inner Mongolia to the tundra of north-east Siberia! One bird was recorded on southward migration and was following a different route. Overall the results create as many questions as they answer but were certainly more effective than hoping for ringing recoveries.

It is unfortunate that the tags from last year have all stopped. We don't know the cause but probably some were hunted, some tags have fallen off and others may simply have stopped transmitting. I understand that a signal was received from one of the Wigeon last week, but was not good enough to calculate the location.

Among the birds trapped this week were two Wigeon which had been previously ringed in HK (one in 2005, one in 2006), so we know that these birds do return to HK in successive winters.

As Katherine mentioned, there are two types of tag this year: an Argos tag (which is the same as used last year) and a GPS tag. The GPS tag should give more accurate locations, but is heavier so can only be fitted safely to the larger birds (>750g). So far most of the tags have sent a transmission, but most of these are fairly weak, probably because the solar panels are not yet fully charged. It is expected that more accurate locations will be received in the next few days.

We have also collected feathers from all birds trapped, which will hopefully be used in stable isotope studies to help establish the breeding ranges (or moulting locations) of these individuals. It will be interesting to see how this fits with the results of satellite tracking.

Hopefully the tags will keep working again (hopefully until at least the southward migration next year), and we can gain more understanding of where ducks from HK are going to breed.


In fact it is one of the Wigeon which has flown to Guangxi. An interesting mid-winter movement.


It's interesting to see that these have now moved. When I checked yesterday afternoon, the locations outside Hong Kong were not shown. Also interesting to note the similarity of date and of direction to the first birds last year.
One of the questions remaining from last year was whether birds migrated directly overland or took a coastal route. It seems from this year's data that this may depend upon individual - one seems to have gone directly overland, while the other two look like they may have followed the coast. The GPS locations are sent more frequently than the Argos locations (although only one is added each day on the website), so these should help to clarify the situation.

Now it will be really interesting to see where these ducks end up and how this compares with last year's data.


Five Pintail have now departed - four with GPS tags and one with an Argos tag.
I have received some more complete data from our American colleagues on this project (data not avilable on the main website). This shows that two of the Pintail have been flying in excess of 100km/h: one bird covered a distance of 228 km in a two-hour period (an average of 114km/h)!


The latest results of the satellite-tracking project show, for the first time, that one of our Pintail has crossed into the arctic circle. This is the most northerly record so far of a bird ringed in Hong Kong (of any species). This individual is now approximately 5,700 km from Hong Kong and still seems to be heading north, so may reach the arctic coast!

Seven ducks are still transmitting regularly, currently all in locations in north-east China or eastern Siberia. One transmitter is still sending signals but has almost certainly become detached from the duck.

As well as the Pintail mentioned above, we now have our most northerly ever record of Wigeon (a bird in Eastern Siberia 4,300 km from Hong Kong). Interestingly, 2 male Wigeon which remained in HK until early May are migrating together and have now reached the border of Heilongjiang, still together. Also of interest, one of the Pintail is currently using sites in and around the outskirts of Beijing.

Although several transmitters have stopped, the GPS transmitters being used this year seem to be lasting better than the previous Argos transmitters. Hopefully these will last and we will continue to get data on these ducks for some time yet.


Southward migration of the satellite-tagged ducks has now started. After spending the summer in the Arctic Circle, one Pintail has now moved south, covering a distance of at least 1700km in just three days, probably in a single flight. The average speed was at least 23 km/h, but detections along the route suggest it may have been flying at as much as 45-50 km/h.
This Pintail is now on the Siberian coast, at Khabarovsk opposite Sakhalin. Three tagged Wigeon are also in the same general area, which is presumably an important stop-over for Hong Kong ducks.
Among the other birds, one Pintail is still in the Arctic Circle and one Wigeon is in Heilongjiang. No other tags have transmitted a signal recently.

Check the progress of the birds at:


I've been expecting the birds to move this week as temperatures have been dropping in eastern Siberia (where the birds have been). There seems to have been problems with the website all week, though, so it's good to see it back online today.

In fact, four birds are still transmitting. In addition to those mentioned previously, there is a Northern Pintail in South Korea. The southward routes for all four birds are further east than the routes taken in spring, especially for the bird currently in Japan. It will be interesting to see if they return to Hong Kong, or winter somewhere else...


It seems that I am not the only person checking the website regularly - there had been no update for about 2 weeks until today, and Katherine has reported the change straight away!

There are still 3 birds transmitting. In addition to the Pintail mentioned, there are 2 Wigeon - 1 each in North and South Korea. It's certainly good news that the transmitters are still working and we are still able to get information on the movements of these individuals.

It is interesting that the birds are still so far north. Many ducks have already returned to Mai Po, and these birds were trapped last year on 9th December, only a week from tóday's date. I had expected them to return by now - I wonder if they will come back here, or will winter somewhere else.