zondag 15 juni 2008

Tiengemeten, Kinderdijk and other bird areas - Views in the past and in the future.

Yesterday we left for Tiengemeten: a small isle in the province of Zuid Holland. None of us (Luuk, Frank, Ben and me) had ever been there, but we had heard some good reports of other birdwatchers about this place. Tiengemeten is an island in the Haringvliet. It is the last true island that is left of the Dutch Delta (a large delta where several large rivers end in the Northsea), all the other islands of the Delta are connected by bridges to the mainland nowadays. If you want to read more about the history of the island, read this nice and very readable report: http://islas.ruudbijlsma.nl/tgm_en.htm

Tiengemeten was bought by Natuurmonumenten (an organisation concerned with nature conservation) with aid of the Dutch Government. The main idea was to create a Nature island, with some low-profile recreation. (A fantastic choice since there were all kinds of plans with the island in the past, like the creation of a nuclair power plant or plans for a second airport for the city of Rotterdam). The new plans are immense. Not only is the entire area large (the total surface of the island and the area outside the dikes is over 1000 hectares), the plan also includes to break open some of the dikes, to relocate all inhabitants (the last farmer left in 2006) and in the future there are also plans to get back the tidal movements of the sea by periodically opening the sluices of the Haringvlietdam. This will mean the water will also become brackish again. We only visited the North-east part of the island. There was a strange historic atmosphere with the abandoned houses still present. The fields were gone, the ground lowered and a large part was inundated. The inundated fields were full of birds: about 50 Spoonbills, 30 Little egrets, 4 Black-necked Grebes, 1 summer plumage Dunlin, 4 Grey Plovers, about 10 Mediterranean Gulls, 12 Little Gulls (we even heard them calling), over 500 Black-tailed Godwits (not a good sign, these birds probably lost their nests), numerous Redshanks and several species of ducks.
But the 15 Black-winged Stilts Himantopus himantopus were the best treat of this island. Black-winged Stilts are rare in the Netherlands, to see 15 birds is even rarer. The birds were breeding, we saw at least 4 nests! Then we had to quit our visit, a heavy thunderstorm and rain came closer and closer and we decided it would be safer to leave the open fields and return to the visitors centre.

We took the little ferry and returned to our car.

In the meantime the weather had improved and we decided to continue our trip. We tried the Scherpenissepolder. A Marsh Sandpiper had been reported and we quickly found the bird. Areas like the Schakerloopolder, Het Stinkgat, Krammersluizen were visited. Het Stinkgat looked nice when we arrived. There were some waders present near the viewing point, but when we walked towards it, a group of bored cows decided to bully our day. They decided to take a walk and scare away the birds... On the right, in the picture you can still see the flock of birds flying off...

Yellow-wort Blackstonia perfoliata along the path to the hut of the Krammersluizen:

Our last destinastion of today was Kinderdijk. Kinderdijk got worldfame by it's Dutch mills, but also have a look at the way it got its name (it's a nice legend!). Nowadays these mills are UNESCO world heritage. It's the only place in the world where you can see so many of these types of mills together and it therefore attracts many visitors from all over the globe. To help you out of your dreams: Holland is not full of tulips, we don't walk on wooden shoes and most of the old windmills have already vanished long ago. Nevertheless the mills and hydraulic systems are an important part of our history and it is a good thing this site got on the UNESCO list. I had never been to Kinderdijk before and I must say, I was impressed by the view of so many old windmills. We stood between two newly built houses next to a busy road and looked over the fields towards the mills. It was like watching through a keyhole into the past.

Our goal was not the mills though. A white-winged tern Chlidonias leucopterus had been reported on the ponds right behind the houses. The pond was filled with floating leaves of Yellow Water-lily Nuphar lutea and on these floating leaves there were nests of the closely related Black Tern Chlidonias niger. Black Terns breed in small colonies and prefer to breed on floating plants in fresh water marshes. Sometimes they breed on man-made small rafts, specially created for this species. In winter they stay in large flocks at sea in Western Africa. The numbers of Black Terns decline. In the breeding atlas "Teixeira R.M. 1979. Atlas van de Nederlandse Broedvogels. Pp. 182-183. Natuurmonumenten, 's Graveland" a couple of reasons are hypothesized: Most important reasons are probably the fact that marsh areas and agricultural grassfields were drained and waterlevels were lowered. Other reasons probably are the strong decline of the plant Water Soldier Stratiotes aloides, the decline of large insects, and increased watertourism. I can understand the watertourism problem; when we arrived there were two people fishing, their boat was very close to a nest of a black tern. The fisherman probably weren't even aware of it. The nests are not strong at all and a large wave would probably make it sink...
Just immediately after we parked the car, we saw the White-winged Tern. We were very lucky, since 2 minutes later a Marsh harrier (a bird of prey) arrived. All the terns were alarming and trying to get the harrier away from their nests. The White-winged Tern joined the other terns. But then when the Harrier flew off, so did the White-winged Tern without any obvious reason. We waited for about half an hour (and enjoyed the still present Black terns), but the White-winged didn't return. We decided to leave it, and went home.

zondag 8 juni 2008

CES Constant Effort Site - Bird ringing

CES, or Constant Effort Site is a specific method of bird ringing. The idea is to monitor birds over a long period of time, with standardized methods. If you keep record of the age and sex of the birds and if you also record recaptures (i.e. when you catch a bird, that you've already ringed before), you are able to tell something about the demography of the birds in your area. The ratio of adult and juvenile birds give an impression of productivity, the recaptures tell you something about survival and site fidelity. Off course the power of your reasearch is in numbers. Not only the numbers on your own location but also the numbers of the hundreds of other CES ringing locations in Europe. This large dataset could be a powerfull tool for monitoring population changes. I'm not going into more details about the CES methods and guidelines. If you want to read more about these things, please read the EURING guidelines for CES ringing in Europe (Pdf)

One of the important things in CES ringing is the ratio Adults:Juveniles. If you want to produce data for this ratio, you have to have knowledge about the plumages of the different age classes. Sometimes it's very obvious a bird is a juvenile: There are bird species that have a juvenile plumage which is completely different from their adult plumage. For example the well known Robin Erithacus rubecula: On the picture below you'll see a juvenile bird on the left and on the right an adult bird. The juvenile looks completely different, doesn't it? You could hardly believe that the spotted brown bird grows into a brightly coloured individual. The Pictures are taken at "Vogelringstation Meijendel" in the dunes of Wassenaar.

In those cases it's easy to tell the age, but you have to know how the juveniles look like, otherwise you might think you're dealing with a complety different or even unknown species.

There are also cases in which it isn't that easy to tell the age and you have to look for more subtle differences. Sometimes it might even be possible that those subtle differences don't exist and you have to do without an age classification. Some feathers (or all, depending on the species) get moulted during the season. When feathers are moulted, it might be more difficult to age the birds. Have a look at the Winter Wren Troglodytes troglodytes: On the left you see a juvenile bird, which lacks the white tips of the undertail feathers. On the right you see a bird that was photographed in October. It shows white tips of the undertail feathers. Is it then an adult? No, sorry, you can't tell. First calenderyear birds (1cy) moult their body feathers in the end of summer (so also their undertail feathers). Once moulted, there's no difference between the undertail feathers of adults and of juveniles.

So during CES you constantly have to be alert to make the right ageing decissions. As I help as a volunteer on the Bird ringing station Meijendel, I will try to show you more often what we are doing over there and how you could age, sex or identify different birds.

During CES, we spend quite some time around the ringing area, in the middle of a beautiful nature reserve. As a bonus for our efforts, we often get to see a lot of other nice birds, plants, mammals and amphibians. Today was really special, I got a magnificent view of two Golden Orioles (male and female) Oriolous oriolus. We heard the male calling all morning long. But getting to see them is something different. Orioles spent most of their time high up in the canopy. Deeply hidden between the leaves and branches of the trees. But if you're willing to put some time into it, there's a good possibility of seeing them. So I decided to wait and search the canopy. Then all of a sudden the male showed itself. It was singing completely free on a dead branch (I made a painting, so you get an impression of the splendor of this species). There we no leaves or branches blocking the view. It was absolutely marvellous! Then I even got to see the female. I was daydreaming of catching them on our ringing station, but off course this will never happen. Ah well... it's always good to keep something to wish!

zaterdag 7 juni 2008

The Goat-Sucker - Caprimulgus europaeus

No, I'm not talking about cryptozoology. So sorry, this is not a story about the Chupacabra monster, also called the Goatsucker. Nor is it about new swearing words or strange sexual obsessions. It's about nightjars and other nocturnal birds.

The European nightjar Caprimulgus europaeus, bears in many countries a name that's related to the sucking of goats. Goatsucker, what a strange name, isn't it? Does it really suck goats? No, they prey on large insects. The name goes back to ancient Greek times and is based on folklore. Nightjars are active from dusk till dawn. The birds can sometimes be found near catle, probably because the cows and goats flush large insects, which the nightjars eat. Mysterious birds, night active and in the neighbourhood of goats... what would you think? Off course: they must be drinking the milk of the goats and make them sick.

Nightjars and the combination with the landscape in which they live, leave a mystical impression. If you go to the right places (moorland, forest clearings, heathlands) in the right time of the year (they are summer residents and migrate in winter to Africa) you might be able to find one. Numbers are increasing in the Netherlands, so your chances of seeing one will also increase. When the sun sets and night comes, you hear a churring sound*, first coming from far and flowing over the moorland. It is not monotonous, the churring changes a bit in highth and slowly you get hypnotised. It's a pleasant feeling, the temperature is warm for a night, moth are flying around you and you dream away. Then you hear a "sqeek" sound * and then a rolling and a bit gutteral "kroo...kroo..kroo". All of a sudden you're out of your dreams, the bird flies above your head. Fantastic! If you're really lucky you can also hear them clapping their wings. I'm not sure how this "kroo..kroo.. kroo" sound is produced, it might be made with the wings, you can hear it at the end of this recording: http://waarneming.nl/sound_details.php?id=902. The males have a white patch on their underwing, probably used in courtship. It is said the males strongly react on white objects. I'm not so sure about this. I still lively remember an episode of Bill Oddie goes wild, where Bill Oddie runs over the moor with his white handkerchief, without succes... We however did try the white object trick with a white shirt and it seemed to work, we got a nice view of a bird flying over our heads, so it might be worth trying!

Tonight we (Ben, Reinder, Luuk and me) left for a long trip. On the programme were Common Quail Coturnix coturnix, European Nightjar Caprimulgus europaeus, Corncrake Crex crex, Baillon's crake Porzana pusilla, Spotted crake Porzana porzana, and with some luck maybe some owls. Apart from the Corncrake, we got them all. It was a nice night, and also Luuk's birthday, which we celebrated at midnight. The evening started with Common quail. When we arrived at the place where we hoped to hear them, there was no activity at all. When we gave up hope and just wanted to go, we heard a bird calling from a ryefield. We heard the "wet my lips" call *. We waited for about half an hour when we suddenly saw a bird crossing a path between a grassfield and the ryefield! My first real sighting of a quail ever. All my other birds were only on sound. That was a good start! We even saw one flying, which is a rare sight, since they are reluctant to fly. Even when they are flushed, they prefer to crawl away under the vegetation in stead of flying. They do however fly over large distances: they migrate to Africa in winter.
(I made the drawings of the nightjar and the quail, since I couldn't get pictures this night. I also don't want to take too many pictures, since you sometimes have to be careful putting too much effort in getting a picture while you should actually enjoy the birds you are watching!)

We decided to go on and searched for a good spot for nightjars. We didn't have an exact location, but the area looked suited. When we were waiting for the nightjars, we got a magnificent sighting of a hunting Long-eared Owl Asio otus. I had never seen a Long-eared owl like this, in the back we heard it's young calling. A couple of hundred calling Natterjacks Bufo calamita (toads), blurred the first nightjar. Then when we walked on, we heard the nightjar better and got to see it. Beautiful birds with their strange jarring sound (they get their common name from this jarring in the night), their long wings and tail and their rather slow flight. There were at least two birds calling at this location.

We left the area and headed for the Baillon's crakes. Luuk and Ben hadn't been there this year, for me and Rein it was the second time this week. But it was Luuk's birthday so we didn't care. We tried a Corncrake but weren't succesfull. Tired, but still hungry for more species, we got a nice Little owl and ended the night with a Spotted crake (we heard it's call, which sounds like a whip). Birding by night, fantastic experiences, but it's a shame you always get so tired of these fanatic tours.

* The churring, the "Squeek" and the "wet my lips" soundrecordings can be found on Latvian Birding: http://www.putni.lv/index_balsis_eng.htm

woensdag 4 juni 2008

Creatures of the night - Baillon's Crake

Learn to reverence night and to put away the vulgar fear of it, for, with the banishment of night from the experience of man, there vanishes as well a religious emotion, a poetic mood, which gives depth to the adventure of humanity. - Henry Beston - *

Last night we (Rein Genuït, Remco Hofland and I) did some nocturnal birding. Birds at night is something completely different from birds by daylight. It's a whole new dimension, which I discovered about 10 years ago, when I helped as a ringing assistent on a project for Corncrakes Crex crex. First of all you have to get used to the fact that there's no or hardly any light. Your eyes are useless, it's your ears that count! Although this looks obvious, it took me some time to get used to this idea. Even up to now, you can find me wearing my binoculars by night, even when it's pitchdark and impossible to see anything. I'm probably still in denial...
Our main goal this night, was to hear some of the recently reported Baillon's crakes Porzana pusilla. Baillon's crakes are beautiful birds, but they are very hard to see, at least in the Netherlands they are. If people see one, it is often a glimpse, like in this youtube movie:

You have better chances at night. You won't see them but you will hear them. Their calling activity is higher at night, like most raills. I never saw a Baillon's crakes and they are rare in the Netherlands: Between 1800 and 1997 there were at least 93 sightings in the Netherlands (but I wouldn't be surprised if numbers of sightings were higher). In 2005 there were at least two confirmed succesfull breeding attempts (where young birds have been seen) in "Polder Achteraf" and in the "Nieuwe Keverdijkse Polder". This was the first time since 1972 that breeding was confirmed.

Apart from the confirmed breeding records in 2005, there are a few historic reports of breeding Baillon's crakes in the Netherlands (about 15 between 1863 and 1972) and I think I have also heard of eggs and nests in old English museum collections that were once collected in the Netherlands. At the time these eggs and nests must have been collected there were not as many people concerned with birds as nowadays but still they managed to collect nests and eggs of this illusive species. These old records (if they really do exist and if they are correctly tagged) might therefore suggest that Baillons crakes used to be a commoner breeder in the Netherlands. Baillon's crakes are of least concern according to IUCN criteria, they have a large distribution in Europe, Asia, Africa and Australia. The African and Australian population is resident, the European and Asian population are migratory. Although the world's population is probably large, there's to my opinion a need for more research. The migration routes and the population size is not well known. This bird is one of the least known birds in Europe, mainly due to it's illusive lifestyle. The European population is very scattered and as far as I know they are nowhere abundant. The population may have declined, and if so, it is probably due to habitat destruction. They are very illusive in their breeding territories and are maybe commoner than we think because birds get overlooked. On the other hand, their calls can sometimes be confusingly similar to frogs or a Garganey, so some of the identifications from the past might be wrong and numbers could be even lower. Beaman and Madge for example, warn in their book "the Handbook of Bird identification for Europe and the Western Palearctic" for published sound recordings of this species that were in fact recordings of frogs!

If you like to read more about them, this site is a good starter'and off course Wikipedia.

We heard the two of the reported birds of Polder Achteraf in Breukelveen in the province of Utrecht. It was a strange experience, standing there at night, in the middle of nowhere with your hands behind your ears to be able to listen even better, with about ten other birdwatchers. We heard frogs everywhere, two grasshopper warblers, a Mole cricket and a Waterrail and then we heard the Baillon's crakes callinig. Apart from the joy of listening to this species (for Rein it was even a lifer), we also came to hear the specific calls these birds were making. They were not producing the usual male advertising calls *, but made a strange and interesting sound *. I recently found out through the Waarneming.nl forum that in 2005 some Dutch birdwatchers were confronted with a call they suspected to be of a Baillons crake, but nobody knew for sure if it was really that species. They recorded the sound* and when they played back the call, all of a sudden a Baillon's Crake showed up, they were even able to film the bird. They had lured the bird with the sound they had recorded and were able to pin this sound to the species. At least in 2005, 2007 and this year the same call was heard at Polder Achteraf (it was also recorded and compared to the Friesian recordings). Rumours are, these calls might be of female birds, but this needs to be confirmed. There's still so much for us to discover, especially in birdsounds and most of all in nocturnal birdsounds!

I ended this night with a Savi's warbler singing on my newly discovered local patch and with two very nice Hedgehogs of which this is one:

* (I'm not so much into quotes, I'll be honest to you, I got the Henry Beston quote through this website: http://www.quotegarden.com/ To be even more honest, I'm always a bit annoyed about those webpages that start with quotes. So my humble excuses to the people who feel te same. But I liked this one and since I didn't have many pictures and since I had to start with something I fell in the trap and used it anyway.... so I wouldn't be surprised if you'll find more quotes on my blog in the future... )

*The soundrecording of the "strange and intersting sound" of a Baillonscrake was recorded on the 1st of June 2008 by Mathias Ritschard and can be found on the http://dutchbirding.nl/ website. Click in the left menu on "sound gallery" and search in the gallery for Baillons crake ("kleinst waterhoen" in Dutch).

*The sound recording of a usual male advertising call was made by Teus Luijendijk on 22nd of June 2004 and can be found on the http://dutchbirding.nl/ website. Click in the left menu on "sound gallery" and search in the gallery for Baillons crake ("kleinst waterhoen" in Dutch)

*The soudrecoring of 2005 is from Dusan Brinkhuizen and can be found on the http://dutchbirding.nl/ website. Click in the left menu on "sound gallery" and search in the gallery for Baillons crake ("kleinst waterhoen" in Dutch)

zondag 1 juni 2008

Do it yourself Lesser yellowlegs

Yesterday we participated in a Birdrace. The whole idea of this Birdrace was to combine a Big Day with casual birding. It's the combination of both that make things interesting. We discovered a nice surprise on this event. (The picture above shows my four friends (Luuk, Frank, Ben and Sjaak) with whom I participated)

On a normal Big Day you start with a team and you get as many birdspecies as possible in a fixed area within 24 hours (period can be shorter but has to be within a calender day, so from midnight to midnight). The area could be a province, a municipality, a place where you often go birding, a country or whatever geographical borders you and your friends like to set. The rules themselves are not that important, but it's important everybody who participates, plays according the same rules. Most of the important rules are about:

  • Which birds are countable and which aren't? (How to cope with injured birds, introduced species, escapes and established species?),

  • How many people of a team have to see a species, before it gets a tick on the list? Most days work with the rule that all members of a team have to see a birdspecies (or at least a high percentage of the team members). There are two main reasons for this. First of all, for the fun of the team; everybody likes to see as many species as possible. The team has to stay together because only this will give them the highest daylist. It's communal benefit, your teammembers help you and you help your teammembers in getting as many species as possible. The other reason to have this rule is to diminish problems with wrong identifications. On days like this, you're prone to make mistakes because you're in a hurry and want to see... nééd to see ... a species. On such moments it is always good to have a critic second opinion by a teammember.

  • Are you allowed to use information by people who are not members of your team, during the day?

To get an idea of these rules, read the rules of the American Birding Association:

Many birdwatchers in the Netherlands don't like this way of birding. They probably think it's much to stressfull and overdone. Often it is hard to get enough people who want to join you on such a day. The Birdrace we participated was however different from normal Big Days. The most important thing (apart from just having fun) was to realise a big specieslist. Not for individual teams but for the total of all the teams. There were prizes for the best discovery of the day ánd for the team with the longest species list. So therefore teams could chose wheter they would come for quality or numbers, or off course both. Actually there were no rules, apart from time and area. The area (provinces of Friesland, Groningen and Drenthe) was an area where we were not really familar with. That is, we didn't know every exact location of commoner species. It is clear we could therefore probably never win a normal Big Day in this region without days of extensive pre-research. We didn't put effort in pre-research, since we just wanted to join for the fun of it. And because we already wanted to go to the area and because we liked to contribute to the total list, we subscribed ourselves.

Our real idea behind this subscription was off course, to profit from the succes of other birdwatchers ;-) About 50 good birdwatchers joined and it was only waiting for something good to show up. We decided to take it easy and look for some stuff around the Lauwersmeer. We didn't receive any phonecall from the organisers of the race. What was going on, no rarities? We phoned Martijn Bot, but he was also surprised that nothing really good had been seen. Apparently it was up to ourselves whether we would see something good that day. Things were not really bad, we had seen a White-tailed eagle Haliaeetus albicilla, a brown variety female Cuckoo, heard a Eurasian Golden Oriole and seen some other nice birds, but we were a bit disappointed by the low numbers of waders. When we arrived in the Ezumakeeg (probably the best place in the Netherlands for waders), things were looking bad. The birds where we had hoped for (Broad-billed Sandpiper, Black-winged Stilt, Red-necked Phalarope) were all gone. Then we got a telephone call by an other team. They discovered a Little Bittern Ixobrychus minutus. Before we would go to there, we decided to finish our check of the Ezumakeeg first.

What a fantastic decision! Only a few minutes later we discovered a Yank! An american wader: the Lesser Yellowlegs Tringa flavipes. It was Frank van Duivenvoorde who found the bird first. He first thought it was a Marsh Sandpiper Tringa stagnatilis but things weren't right. Then the bird flew a few metres, and things were getting clear. About the size of a Redshank, but much more slender. The bill was fine, the neck gracious and the bird looked longer. The legs were yellow to yellowish orange. But most important, there was no sign of a white triangular rump patch. There was only a square white patch, like in Wood Sandpiper Tringa glareola. It was flying towards us and landed at about 30 metres away from us. Luuk, put the sighting on the pagersystem and I called the co-ordinator of the Birdrace, so that everone was aware of this rarity. Then within a few minutes, it flew off to another place where it was later rediscovered by some other birdwatchers at far greater distance. We were really lucky, to get such magnificant views.
See better pictures from Sjaak and Luuk here:

And even better pictures from one day later:

We won the prize for the best discovery and got a lot of congratulations (and the total of all the teams together was 181 species!). It made birding that day a lot more relaxed. We scanned some other places and then returned to the Ezumakeeg to have a last look at the Lesser Yellowlegs. At the north part of the Ezumakeeg, where we discovered the Lesser Yellowlegs, were some Ruffs displaying. Before leaving we enjoyed their magnificant plumages and beheaviour, then we went home. Satisfied after a good day of birding!