• Vincent

The 2019 technical ringing report for Meijendel, Zuid-Holland, the Netherlands is out now!

Report (in Dutch) can be downloaded here (pdf; 4MB). The English summary can be found both below and in the report.

SUMMARY In many ways, 2019 was a fairly predictable year for our ringing site in Meijendel, Zuid-Holland, the Netherlands. During 62 days (450 hours) between February and November, we ringed 5470 birds and controlled an additional 716 (13%), divided over 70 species. With the average number of species being 78 over the past ten years, it was therefore a poor year for species diversity. One new species was trapped: Sand Martin. Eight species reached record numbers: Blue Tit, Cetti’s Warbler, Spotted Flycatcher, European Stonechat, White Wagtail, Tree Pipit, Brambling and Eurasian Siskin. We participated in the international breeding bird monitoring project CES (Constant Effort Sites) for the 20thconsecutive year. In 2019 we ringed a high number of adult birds, and a reasonable number of juveniles. Nuthatch was a new CES breeding species, whereas the Wryneck (also new within the CES) was a proven migrant: it was found dead 117 km northeast of our ringing site two days later. During July, the peak season for dispersion of juveniles and the start of autumn migration, we were less active than usual and on the days we were active, the results were poor. The number of young Nightingales within our long-running project on dispersing juveniles was therefore disappointing: over the past 20 years, we trapped fewer individuals in 2017 only. In August we ringed on a regular basis, but the number of birds was fairly low for this time of year. During September and the first half of October long-lasting ocean depressions brought a lot of wind and rain, which seriously limited the number of suitable days for field work. From mid-October to mid-November the weather was generally much more favourable, so until the end of the migration season we were able to ring regularly. The number of birds per day was high during these weeks, with a peak of 328 birds on 19 October. Also, the 26 species trapped on 29 October are worth mentioning. Autumn saw an invasion of Blue Tits and a Goldcrest influx. The rise of the Cetti’s Warbler continued, and for the first time since 2001 Siskins were trapped more than occasionally. For a countrywide survey on zoonoses (diseases that can be transported from animals to humans) – a collaboration between the national ringing scheme and Erasmus University (Rotterdam) – we collected blood samples of 107 birds of 23 species. A Song Thrush we sampled appeared to be contaminated with the Usutu virus (the virus that has decimated Blackbird populations in NW Europe). For the first time since 2009 we did not collect any feather material of Chiffchaffs for DNA analysis. We finished the draft of our second paper on the subject in collaboration with professor Peter de Knijff (Leiden University), which is expected to be published in 2020. The only feathers we collected this year were of a presumed (and later confirmed) Siberian Lesser Whitethroat. In 2018 we were involved in a pilot study on Common Starlings, an international collaboration between the national ringing scheme and German (Max Planck Institute) and Swiss researchers. Although the pilot was successful, the start of the project was unfortunately delayed due to both technical and financial complications. As soon as these issues are solved, we are ready start the fieldwork for this study. Hopefully we can pick this up in the near future. Outside Meijendel an additional 414 birds divided over 16 taxa were ringed (including ten species not ringed at our regular site) for several RAS (Retrapping Adults for Survival) projects (Jack Snipe, Barn Swallow, Yellow Wagtail), or for educational purposes. Thereby a grand total of 5884 birds of 80 taxa were marked by our ringing group in 2019. Other highlights included our chairman Wijnand Bleumink being appointed Ringer of the Year 2019 by our national ringing scheme and the Ringersvereniging (the association that represents the interests of ringers). A well-deserved acknowledgement for a devoted volunteer who has been a fully licensed ringer since 1958. An article on Nightingales by Peter Spierenburg and Morrison Pot was published in Holland’s Duinen. It describes the correlation between the density of territories from year to year (based on breeding bird surveys and our CES data) and fledged juveniles (based on our ringing data of dispersing juveniles). In short they are negatively correlated: the higher the density of breeding pairs, the lower the number of juveniles. Peter gave a lecture in front of a large audience during the Sovondag, the biggest birdwatcher’s fair in the Netherlands: a fantastic way to promote our work.

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  • Vincent

pic: Ellen de Bruin


I've added a new piece on Chiffchaffs from Turkey or Transcaucasia to the site. Vagrants to NW Europe are now proven! But can we identify them in the field? Maybe we can!


Check here.

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  • Vincent

Bijgewerkt: 15 mrt 2020


Recently, a British rarity committee member asked how we deal with ‘Russian Jackdaws’ (ssp. soemmerringii) in the Netherlands. Incredibly, a day later I saw my best candidate in years. I didn’t have any birding equipment on me, so I had to use my phone to photograph it.



The commonly accepted (assumed?) situation in the Netherlands is that the dark ssp. spermologus is common year round*, that ‘Nordic Jackdaw’ (ssp. monedula) is a migrant and winterer (proven by rings) and that 'Russian Jackdaw' (soemmerringii) is a (very) scarce winterer.


ID challenges The problem is that Jackdaw variation is clinal and the ID is often problematic. There are intergration zones in Eastern Europe, and there's huge individual variation within populations (e.g. only half of the Russian Jackdaws have these long white neck marks; Shirihai & Svensson, 2018). So the dividing line between some individual Nordic and Russian Jackdaws is thin – very thin.


The best sources on the matter are probably Offereins (2003) and HWBP (Shirihai & Svensson, 2018), though they are confusingly contradicting at times. More on that later.


The return

A week later I returned to the site prepared. I conquered the storm and the dark clouds and managed to see the bird for a whole 3 minutes before it was flushed by a dog. It looked so dark, with the white in the neck so prominent, that I figured it was a Russian. Ok, I made some critical remarks, but still: I was too quick on the draw...

The return #2

A couple of days later I went back once more to observe and photograph it in better light conditions. I quickly found the bird. And the doubts kicked in immediately.

There are no moult limits, so this is an adult. But this is of no use for the ID. At least in soemmerringii the amount of white in the neck is not age-related (Shirihai & Svensson, 2018).


Overall the bird looked much greyer than during the dark weather earlier that week. Shoot! On a wanderer from the east I want to see nearly black underparts, as described by Offereins (2003) for 'classic' (extreme?) Russians. Contradiction #1: Shirihai and Svensson (2018) don't mention this. They even write: "[soemmerringii] has dark grey rather than near-black underparts (thus close to monedula)." ??? Confusing!


The underparts were more mottled than I noted before (one of my initial 'critical remarks'): a 'Nordic' feature according to Offereins (2003). Contradiction #2: again this is not mentioned by Shirihai & Svensson (2018).


Intriguingly a bird from Finland credited as a presumed soemmerrengii in HWPB looks pretty similar. Its ID is based on the 'slightly paler grey on head' and 'distinctly whiter half collar'. But Shirihai & Svensson (2018) also add: "much individual variation, and extremes of monedula can be very similar". 


It's indeed not dissimilar to birds I've seen in soemmerringii country. Check this one from SE Bulgaria (2011) and note the similarity of the grey and - yes - strongly mottled underparts. The main difference is that the Bulgarian bird has somewhat scalloped upperparts - a feature Shirihai & Svensson (2018) do and Offereins doesn't mention for Russian. And in fact it has a somewhat less white collar:

So my bird definitely wouldn't stand out as something odd within the breeding range of soemmerringii. But a more prominently marked Nordic cannot be excluded, not on current knowledge anyway, and since these are default the tentative ID should probably be: presumed (extreme?) Nordic / possible Russian


Now what? The two sources mentioned above fully acknowledge the problematic ID (cline, integration, individual variation). They are contradicting on some points. The thing is: pics in these articles are mainly from wintering birds, which IMHO makes their ID rather tentative. So who's gonna make 100s of shots of soemmerringii wintering within within their eastern breeding ranges?  

* PS Please note that Shirihai & Svensson (2018) mention that Dutch birds are probably best included in monedula instead of spermologus. However, a pic from Holland in the species account is nonetheless labelled as spermologus! It only adds to the confusion and probably perfectly reflects the clinal variation.


References

Offereins, R. 2003. Identification of eastern subspecies of Western Jackdaw and occurrence in the Netherlands. Dutch Birding 25: 209-220


Shirihai, H. & L. Svensson. 2018. Handbook of Western Palearctic Birds. Helm, London.

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