Diana is super, and back in March she agreed that I could come spend some time with her and Sergei in the field. So I took my second trip out to Lazovsky District in mid-May (this time it was much greener than in mid-April!), and I not only got a chance to see Diana and Sergei’s work in the field, but also to talk with them about everything from science to education to politics to the zapovednik system. They are both fantastic people, and I had a great time.
About Mergansers and Diana’s Research
Mergansers are a rare species found only in the Russian Far East and Northern China; they winter in
Because Diana does work on marine ducks, she has worked not only in the Russian Arctic but also in the places these birds migrate to – the
The location: Diana and Sergei work in 4 adjacent districts in the Primorye Region, but they do most of their work in the Lazovsky District. The field season: late March to late May. The last two years they have rented a house in Kishenyovka, a village of 240 people located in the Lazovsky District on the border of Lazovsky Zapovednik. (Diana estimates that of these 240 people, maybe 5 of them are employed. The rest don’t really seem to want to work, and how they spend their time was beyond Diana and Sergei. Obviously, they are a threat to the zapovednik, since they can easily cross into the territory and illegally fell trees, collect herbs, etc.)
The science team: Diana, Sergei, their field and equipment assistant, also Sergei, and Diana and Sergei’s very happy 3-year-old black lab, Joy, are constantly together. Valery Shokhrin, a Lazovsky Zapovednik scientist who is a specialist on predatory birds, also often joins them in the field. And then they have visitors like me, or like Tony, a marine birds specialist from
Mergansers nest in tree hollows on river banks, and a big part of Diana’s research focuses on studying places with changes in habitat, where trees along the river may have been chopped down. In the Lazovsky District a decent amount of forest along the rivers has been logged, and one hypothesis is that now there may not be enough nesting sites for mergansers here. Therefore Diana and Sergei have been putting artificial nests about 20 feet high up in trees since 2001. (These artificial sites either look just like wooden boxes, or like cylinders or wooden “tubes”.)
Sergei and Diana have placed a total of 140 of these artificial nests throughout the 4 districts where they work, with 45 in the Lazovsky District. In the Lazovsky District they find that about 30% of their artificial nests get used every year, and they assume that there are enough natural nesting sites for the rest of the birds. In the Olginsky District, for example – another of the 4 districts where they work – they find that only 5% of the artificial nests get occupied. Here there is just as much logging of the river banks as in the Lazovsky District, but there are not as many mergansers, so apparently fewer sites are needed.
Organizing the Field Season
Field work in late March starts with cleaning the artificial sites of litter and debris collected during the year, and in March and April Diana begins counting and tagging the adult birds as they return to the rivers of the Primorye Region. They catch the birds by putting nets up across the rivers.
At the end of April they start checking their artificial nesting sites to see if birds are using them. The also check the natural nesting sites that they know about. However, it is very difficult to find natural nesting sites, and they have only found 5 or 6 so far, all in the Lazovsky District, where they spend most of their time. (You have to spend a significant amount of time in a place to find the natural nesting sites – suitable little tree hollows are not necessarily easy to discover.)
Maybe you guessed it – checking the nests (and also putting up artificial nests) involves climbing trees. Sergei is an excellent tree climber. When they do the first check of nesting sites starting at the end of April, if they find a nest and a mother, they don’t catch and tag the mother at this time. This is very important! If there is a mother in the nest, she has most likely just recently laid her eggs. If they were to catch her, she would probably abandon the nest. Therefore they wait to catch and tag the mother until after she has made a significant commitment to the nest and won’t abandon it. During this first check, if a mother is there she will just fly away. Then Sergei will take out the eggs. They count the eggs and record the size and weight of each of them.
They also do a water test to determine how old the eggs are. They take an egg and put it in a jar of water. Eggs laid more recently are heavier and will stay at the bottom, where as older eggs are lighter and will float. They can actually estimate how many days old the eggs are. The eggs take 31 days to hatch, and therefore from the water test Sergei and Diana know by approximately what date the ducklings will hatch and, consequently, by what date they have to come back and catch the mother. (They have to catch the mother before the eggs hatch). Mergansers are like chickens – when they hatch, they are ready to go, and one day after their birth the mother will already have them out of the nest and on the water. They’re not like the typical songbirds in your backyard that spend a bunch of time in the nest getting fed by their mother after being born.
When I got to Lazovsky District on May 11 Diana and Sergei were at the stage of doing the second round of checks of their nesting sites. (I really hoped I might get to see ducklings! But the earliest would not start hatching until I was already getting ready to leave Lazovsky District.) From their late-April check Sergei and Diana already know at which sites there was a nest, and now it was late enough to catch the mother birds at those sites. At the same time the teams also does a second check of all the nesting sites, because it’s possible that a mother just hadn’t nested yet when they checked the first time around in late April. Sergei said last year they found a lot of new birds when they checked the second time around, but this year they have not found hardly anything – no mergansers, and just one mandarin duck nest in the Lazovsky District.
On my first day we went to an artificial nest where Sergei and Diana knew there was a mother and caught her. To do this Sergei (standing on the ground) puts a big net that is on a long pole up to the mouth of the nest; the bird senses a disturbance and flies out into the net. (Obviously, you have to be very quiet when you approach the nest.) Sergei and Diana had caught this mother already last year, and they had not only tagged her but also put a logger on her. The logger reads data about the bird’s surrounding environment (things like salinity, temperature, light and dark, etc.) every ten minutes nonstop, all year long. The loggers were used for the first time last year, and they put them on 8 birds. Nobody really knows where the birds go after they leave the Russian Far East for the winter, so they hope these loggers will provide a lot of useful new information. This was the second logger that they had managed to recollect this year for analysis.
Sergei and Diana weighed the bird, took off the logger and put a new one on her, and clipped a sample of her feathers from under her wing. This sample will be used to do a stable isotope analysis, which should help provide information about the time the bird spends at sea versus in fresh water environments. (Although no one can be certain that mergansers migrate to the ocean in the winter, it is generally assumed that they do.) This bird was incredibly calm; I was amazed.
Later in the afternoon we checked another artificial nest, this one in the shape of a box, rather than a tube. There were two mandarin duck eggs in it, which Diana weighed and measured. Interestingly, mandarin ducks lay one egg every day, usually for a total of about 10 eggs. (Since mandarins and mergansers often use similar nesting sites, Diana and Sergei take data on the mandarin ducks they find in their artificial nests, too. Generally mandarins prefer the boxes, mergansers the tubes, although both use both types.) Mergansers usually lay 10-11 eggs. Usually all of them hatch, but only about 60% then live after the ducklings move out to the river, as they get eaten by predators like eagles and mink. In the first winter it is likely that another 50% die, assuming they move out to sea, as the transition from a freshwater to a marine environment can be a tough one.
Mergansers often return to the same nesting site to hatch, but they’re not like salmon, so this is not required – they can certainly go to new places, although no one is sure how likely a scenario this is. However, Sergei and Diana have been concerned that in the course of their 7 years of work here, they have only come across the same birds (which they can identify because they have tagged them, of course) for 2 or at best 3 years in a row – and then they don’t see them again. This makes them think that mergansers may have a high mortality rate. Mergansers can live about 10-12 years and reproduce at 2-3 years. They survive well in captivity, and in
Pictures: 1. Diana’s husband Sergei holding a mother duck that was caught on my first day; 2. and 3. the