Wim Wiegant
 ·  21 June 2025  16:53

Paul, ik ben het even kwijt, maar is dit nu dat Duitse beest, of juist niet...?

Paul van Tuil
 ·  21 June 2025  18:17

Ha Wim, de kop van Schouwen is buitengewoon populair bij onze oosterburen😃, maar of deze vogel daar ook vandaan komt durf ik niet te zeggen

Tobi Koppejan
 ·  21 June 2025  18:43

De Duitse "Vincenz" is vier dagen geleden al opgeraapt in Duitsland, dus dat kan 'm niet zijn....

Ed van Boheemen
 ·  21 June 2025  19:14

Grappig, op 28 mei 2018 had ik daar (Dishoek/Zoutelande) ook een Lammergier..

Wim Wiegant
 ·  21 June 2025  20:37

Dank voor de reacties, met name Tobi...!

Hans Pohlmann
 ·  21 June 2025  21:50

We zien deze week veel beweging van Lammergieren, zowel wilde als projectvogels. West-Frankrijk, Portugal en Noord-duitsland bijvoorbeeld.

Ed van Boheemen
 ·  21 June 2025  22:33

Intrigerende opmerking Hans: "zowel wilde, als projectvogels".

Hans Pohlmann
 ·  21 June 2025  23:04

Ja, Bizar he?

Paul van Tuil
 ·  27 June 2025  18:51, gewijzigd 27 June 2025  18:51

Nog een sidenote bij toch een beetje mijn vogel :-) De dispersie van Lammergier de afgelopen periode zoals Hans aangeeft is zeker interessant. Gelet op het feit dat deze vogel ongeringd (latere foto's van laagvliegende vogel rond Neeltje Jans) en ongezenderd bleek doet de vraag rijzen waarom dit geen echte wilde Lammergier kan zijn.

Bas Lagerveld
 ·  28 June 2025  00:55

Paul, de CDNA is er kennelijk nochtans niet aan toe om in een andere richting te denken dan op basis van de toelichting op het besluit van maart 2017, zie: Nadere toelichting besluit Lammergier - Dutch Birding

Evenwel, gewoon indienen, en wellicht leidt het inmiddels tot andere inzichten, who knows!

Paul van Tuil
 ·  28 June 2025  06:47

Dank voor de link Bas!, in 2017 is daar grondig over nagedacht. Deze vogel is ingediend, aan CDNA om te beoordelen

Edwin Russer
 ·  28 June 2025  12:37

En de aanvullende toelichting van 2020. https://dutchavifauna.nl/news/1646/lammergieren_in_nederland_en_noordwest-europa_-_inhoudelijke_achtergrond_en_toelichting_besluiten

Max Berlijn
 ·  28 June 2025  14:22, gewijzigd 28 June 2025  14:25

Is er nu nog nieuwe info over recente dispersie van vogels van populaties die niet zijn aangevuld, vermengd(?? als dat ooit is gebeurt) of beïnvloed met door de mens uitgezette vogels (Pyreneeën?). Mijn recente mening dat je de “Wild Born” gewoon moet tellen (dankzij Han) blijft ongewijzigd hoor, maar zou leuk zijn om te weten.

Edwin Russer
 ·  29 June 2025  08:09

Niet specifiek over dispersie van vogels uit niet-geïntroduceerde populaties maar wel het meest recente rapport, voorzover ik heb kunnen achterhalen, over het broedsucces in de Alpen. https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/csp2.70027

Hans Pohlmann
 ·  30 June 2025  08:37, gewijzigd 30 June 2025  08:56

@Max: Dit jaar zijn bijvoorbeeld een aantal vogels (ongezenderd en ongebleekt, dus wildgeboren) gezien in het Sistema Central in midden-Spanje. Deze kunnen uit de Pyreneen zijn gekomen, 450 km naar het zuidwesten vanuit de Pyreneen. Das overigens niets nieuws. In de periode 1990-2004 zijn 9 waarnemingen vastgelegd in de Cordillera Penibetica, 80 in de Cordillera Cantabrica, 22 in het Sistema Iberica en 3 in het Sistema Central (Heredia, 2005).

Ook de in de Pyreneen wildgeboren vogel die in de Alpen broedt (DNA bewezen), broedde er dit jaar weer/nog.

Paul van Tuil
 ·  1 July 2025  21:28

@Hans, de spreiding ten zuiden van de Pyreneeën lijkt i.e.g. de theorie te ondermijnen dat vogels uit dat gebergte gebonden blijven aan het Pyreneeën massief. Vermenging met de populatie in de Alpen is ook interessant en een aspect dat meegenomen kan worden in de overweging of er in de Alpen inmiddels sprake is van een duurzame en zelfredzame populatie.

Vooralsnog hou ik persoonlijk graag de stelling van Max aan: obviously wild born counts

Edwin Russer
 ·  2 July 2025  06:53

@Paul, als je het rapport leest dan kun je zien dat de populatie al self-sustaining is.

In any case, even if the breeding success of reintroduced birds was lower than that of wild-hatched birds, it remained high (ca. 0.7 fledglings per initiated clutch, see Figure 4) as compared with the productivity observed in wild birds in the Pyrenean population (0.41, Margalida et al., 2020), and was sufficiently high to contribute to population growth, ultimately leading to a wild-hatched demographically self-sustainable population in the core areas as recently demonstrated by Schaub et al. (2024)

Paul van Tuil
 ·  2 July 2025  17:21

@Edwin, dankje, mooie conclusie die ik nog niet zo direct in de samenvatting had gelezen. Nu wel in h4. Beleid CDNA geeft aan dat indien er sprake is van een duurzame en zelfredzame populatie in de Alpen het standpunt tav aanvaarding kan worden heroverwogen. Dit artikel legt voor heroverweging (wetenschappelijk) in combinatie met de dispersie vanuit de Pyreneeën een goede basis lijkt mij. Ik ben zeer benieuwd. 

Hans Pohlmann
 ·  2 July 2025  17:52

@Paul, de Pyreneenlammers trekken inderdaad bewezen, hebben ze altijd al gedaan (blijkt uit DNA-onderzoek museumbalgen). Ook is bewezen dat ze minder trekken dan vogels uit andere deelpopulaties, waarbij dan weer bewezen is dat dit voor een groot deel wordt veroorzaakt door de kunstmatige voedselvoorziening in de Pyreneen (overschot door de voerplaatsen).

Vorig jaar was trouwens een mooie testcase. Daar zijn twee jonge vogels uit de Pyreneen losgelaten in Andalusie, voorzien van GPS-zender. Beide vogels lieten geen ander gedrag zien dan de andere vogels die in Andalusie zijn losgelaten, dat jaar of de jaren ervoor. Het zit dus niet in de genen...

@Edwin: inderdaad, dit is daarmee een bevestiging van de resultaten die diezelfde Schaub in 2009 had.

Andreas Noeske
 ·  10 July 2025  10:52, gewijzigd 10 July 2025  13:21

"However, the present analysis also demonstrates that the population has been self-sustainable since 2006." cited from https://besjournals.onlinelibrary.wiley.com/doi/10.1111/j.1365-2664.2008.01585.x

"We conclude that the reintroduction of bearded vultures in the Alps has been very successful in establishing a demographically self-sustaining population. ... The established sampling of feathers, which allows the genetic identification of individuals, is a particularly valuable source of information as the population is increasingly dominated by wild hatchlings, most of which are unmarked and therefore only genetically identifiable. A downside of the otherwise successful reintroduction project is the higher adult mortality and the lower breeding success of the peripheral compared to the core population, which may reduce the capacity of bearded vultures to colonise the entire Alps." https://besjournals.onlinelibrary.wiley.com/doi/10.1002/2688-8319.12347

So, it seems appropriate to upgrade the Lammergier to categorie C5 = "Arten, deren Nachweise aus selbsterhaltenden Populationen im benachbarten Ausland resultieren" according to https://www.club300.de/ranking/info_categories.php, which means "species whose records result from self-sustaining populations in neighbouring countries".

Perhaps this is relevant in the context of your ongoing discussion about categorising the birds of the Netherlands: https://dutchavifauna.nl/news/1955/invoering_categorien_op_de_nederlandse_lijst

Currently in Germany there is also a discussion about an update of the categorisation of Monniksgier and Lammergier. The best category at least for Aegypius monachus seems A/C5. But, according to https://www.researchgate.net/publication/341287351_Liste_der_Vogel_Deutschlands both Bart/Lämmer- und Mönchsgeier are still placed in category BE.

See also this bird https://www.ornitho.de/index.php?m_id=54&id=105956011 which is said by the observer to be of wild origin.

Paul van Tuil
 ·  13 July 2025  22:30

@Andreas, thanks for your valuable contribution in the discussion here, including links to discussion in Germany. Interesting developments and food for thought for our rarerity-committee.

Andreas Noeske
 ·  17 July 2025  10:57, gewijzigd 17 July 2025  12:43

met betrekking tot Monniksgier

The migration of a 3-year-old released Cinereous Vulture between 19th April and 5th July is shown here:
4vultures.org/blog/saving-cinereous-vulture-dryan-a-10000-km-journey-ends-in-a-successful-rescue/

"Tagging consists of fitting identifying rings and a GPS/GSM transmitter."
4vultures.org/blog/its-cinereous-vulture-tagging-time/

So, not every ringed AND with a transmitter equipped Aegypius monachus is necessarily an escaped or released bird, which is shown by the tagging of wild fledged birds in Portugal. This is also true for such birds seen in e.g., Germany, Denmark. A case-by-case assessment is still required.

See also: https://www.dutchavifauna.nl/species/monniksgier

This IBIS-paper is essential reading when it comes to categorising Dutch birds: https://onlinelibrary.wiley.com/doi/10.1111/ibi.13067

Probably there is still a rocky road to go down for the CDNA/CSNA. Nevertheless the outcome will be very interesting for German birders too.

Andreas Noeske
 ·  18 July 2025  10:24

Please have a look at the GPS-map of the migration of „Dome - PN Vanoise - chick fledged July 2022“ here: https://4vultures.org/our-work/monitoring/bearded-vulture-maps/

Upon request I got the answer from the https://4vultures.org/ that „Dome“ hatched in the wild in a nest in Vanoise Nationalpark in France and was GPS tagged and ringed there, crossed the boarder to Germany on the 28th May 2024 and stayed only a few hours before flying back to Austria, Switzerland and France.

„Bird species admitted to the French List are included in the following categories A, B or C, with the same definitions as the British and other Western Palaearctic bird lists. …

Bearded vulture Gypaetus barbatus (French: gypaète barbu) – AC“ https://en.wikipedia.org/wiki/List_of_birds_of_Metropolitan_France

Andreas Noeske
 ·  21 July 2025  11:27, gewijzigd 21 July 2025  11:45

„Schaub et al. (2009) evaluated the reintroduction of bearded vultures in the Alps in the year 2006 when nine pairs were breeding, and it was already then concluded that the population was self-sustaining, ...“ https://besjournals.onlinelibrary.wiley.com/doi/10.1002/2688-8319.12347#eso312347-bib-0022, see also https://besjournals.onlinelibrary.wiley.com/doi/10.1111/j.1365-2664.2008.01585.x

Formula to calculate the date of the establishment of a self-sustaining population according to the application in Bauer et al. (2016) with regard to vagrant birds https://www.researchgate.net/publication/311824717_Vogelneozoen_in_Deutschland_-_Revision_der_nationalen_Statuseinstufungen

year of established population = year of first breeding in the wild + 2x mean generation length, but at least 25 years, i.e. for the Bearded Vulture

2025 (rounded down) = 1997 + 2x 14,2 - Generation length of Bearded Vulture is 14,2 years, taken from https://datazone.birdlife.org/species/factsheet/bearded-vulture-gypaetus-barbatus

Meanwhile (2024) the Alps population is placed in category C in all four relevant countries (France, Switzerland, Austria, Italy). This should mean for the Dutch List that the Bearded Vulture becomes category C5 and is therefore countable in the Dutch Ranking.

Rare birds in the Netherlands in 2015, Bearded Vulture: „An unringed and unmarked second calendar-year was seen at Holterberg, Overijssel, on 5 May, ...“ https://www.dutchavifauna.nl/static/jaarverslagen/CDNA-verslag_2015.pdf

Also this bird (2015) could become countable retroactively (self-sustainable since 2006). Personally I think the mindset in the approach expressed in Nadere toelichting besluit Lammergier needs an update: https://www.dutchbirding.nl/dbactueel/1397/nadere_toelichting_besluit_lammergier

@ all Dutch birders: If I am wrong, please let me know!

Andreas Noeske
 ·  23 July 2025  14:55

I fully agree with Max „dat je de “Wild Born” gewoon moet tellen“.

Cited from https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.4856:

„Among birds monitored for up to 1 year, 24% were “resident,” 28% were “medium-distance explorers,” and 48% were “long-distance explorers” ... These proportions became respectively 25%, 19%, and 56% up to 1.5 years ...“

„85% of the departures occurred between February and June“

„in the spring of their second calendar year, Bearded Vultures increased their movement activities, with a peak of exploration departures concentrated between March and June, and displayed larger home ranges. After 1 year, more than half of the Bearded Vultures have displayed long-distance explorations, usually characterized by short but intensive traveling periods (~10 days), and about 20% of birds have exhibited medium-distance explorations over longer time periods (~40 days)“

I doubt that wild hatched cat. C-birds differ in their movements from released cat. E-birds.

The recent decision https://www.dutchavifauna.nl/static/publicaties/CDNA%20Definitief%20Plan%20van%20aanpak%20categorie%20D%20120725.pdf, even if preliminary, to place the Bearded Vulture in category D is not only rather disappointing but also wrong.

D means „Doubtful“. There is no doubt that the bird shown above is an unmarked 2cy bird hatched in the wild most probably stemming from the meanwhile self-sustaining Alps population. This bird is therefore placed in category C5.

There is also no doubt that the female 'Eglazine' https://www.movebank.org/cms/webapp?gwt_fragment=page%3Dstudies%2Cpath%3Dstudy232133400+individual1295748187 which is treated in https://www.dutchavifauna.nl/static/jaarverslagen/CDNA-verslag_2021.pdf has to be placed in category E = „Escapees“ or in this case better „released“. For categories used in Germany see https://www.club300.de/ranking/info_categories.php.

So, there is no place in category D for this species because there is no doubt!

Dutch birders who have seen 'Eglazine' unfortunately cannot count this bird in their ranking lists, whereas those who have seen the bird above are in luck and can count it.

For years to come you will need both category C5 and E. As Max already stated: Count the wild ones!

Of course, we have the same problem in Germany and the discussion is not finished yet. So, in this special case the CDNA still has some way to go to be taken seriously, I think.

Peter de Knijff
 ·  23 July 2025  16:43

Andreas, first, “counting a bird” by a birder in the Netherlands is a decision that has nothing to do with the CDNA. Those who agreed to participate in the counting-game are, in theory, free to decide which categories they include in their counts, irrespective of any CDNA category or Dutch list decision. Hence, they can decide to include e.g. any bird in A-D in their counts. Second, the CDNA has wisely decided not to subdivide any of the category’s A – E. Therefore, we only have C.

Andreas Noeske
 ·  24 July 2025  11:56

@Peter

cited „first, “counting a bird” by a birder in the Netherlands is a decision that has nothing to do with the CDNA.“ ???

Please see Telregels Nederlandse ranking: „Voor de volledigheid merken wij hier op dat Dutch Birding, en dus ook de Ranking, zich volledig conformeert aan het handboek, de richtlijnen en besluiten van de Commissie Dwaalgasten Nederlandse Avifauna (CDNA).“ cited from https://www.dutchbirdalerts.nl/page/1480/telregels_nederlandse_ranking

To me this means that counting birds in the Netherlands HAS something to do with the decisions made by the CDNA.

cited „Those who agreed to participate in the counting-game are, in theory, free to decide which categories they include in their counts, irrespective of any CDNA category or Dutch list decision.“ ???

Wrong again! Please see Telregels Nederlandse ranking: „Gevallen van beoordeelsoorten die zijn aanvaard door de Commissie Dwaalgasten Nederlandse Avifauna (CDNA) zijn telbaar wanneer deze gevallen verder voldoen aan de telregels.

Gevallen van beoordeelsoorten die zijn afgewezen door de CDNA zijn niet telbaar. Beoordeelsoorten zijn als zodanig (op het moment van publicatie van deze telregels in het oranje) aangegeven in de lijst van de Nederlandse Avifauna.“

Again, as long as one does not live in a closed parallel universe, counting birds HAS something to do with the decisions made by the national rarities committee at least in my world, in Germany and according to the DB-rules also in the Netherlands.

Putting the Lammergier in category D is the wrong way. Only in Germany, unfortunately, e.g. all New World Sparrows are placed in category D and rightly, the rest of Europe is just smiling about that. Please do me a favour and do not behave as the Germans do!

Concerning category C in a few tens of years perhaps a new generation of dutch birders will eventually end up in categorising birds as it is already done e.g. in the UK https://bou.org.uk/british-list/species-categories/ and in Germany https://www.club300.de/ranking/info_categories.php.

In my opinion the Dutch AND German category for the Bearded Vulture should be C/C5 AND E. At the moment in German we have category B and E3 for it. To me it seems very useful for future generations to have both these categories so that you can see if the relation of observed birds in the Netherlands and Germany perhaps shifts towards C/C5-Lammergieren eventually outperforming E-Lammergieren by far.

Peter de Knijff
 ·  24 July 2025  17:06

“zich volledig conformeert” simply means that those who feel (or are) responsible follow the decisions of the CDNA. This, per definition, also implies that they can decide NOT to follow the decisions of the CDNA. Or, as I wrote, the CDNA has nothing to do with the counting game, nowhere in the rules and guidelines of the CDNA is stated that they are responsible for the counting-game. And this is perfectly fine.

To put it simply: if those who feel responsible for the counting-game rules decide to include any bird in A-D (or even A-E!), that’s it.

And yes, I see the various subcategories, e.g. in C or F, as rather ridiculous, purely anthropocentric and very irrelevant. I dare even to state that I would like to see, if one wants to think in terms of National lists, only A, B, and anything fishy in C. Alas, that is, I fear, at present a bridge to far.

Arnoud B van den Berg
 ·  24 July 2025  22:59

Hi Andreas

You say "...Dutch birders will eventually end up in categorising birds as it is already done e.g. in the UK ... and Germany". Your wording suggests that birders in the Netherlands are lagging behind but that doesn't do justice to history. 

What history? In Dutch Birding, categorising birds was 'already' done more than 45 years ago: in the annotated checklist of all species and subspecies recorded in the Netherlands until 1980 by Gerald Oreel. You can find this publication in Dutch Birding 2: 41-47, 82-105, 1980.

Since then, the Dutch Birding categories (A, B, C, D1, D2 D3) were adopted and extended in many other countries while, on the other hand, within a couple of years Dutch birders and committees agreed that the administrative hassle was becoming so 'laughable' that categories were abolished; eg, for the reasons mentioned by Peter de Knijff (above). Since then, for more than 40 years, there was only category A in the Netherlands (B and C being used provisionally) and NO category D.

Last year, the Dutch rarities committee decided to re-establish categorisation. Not sure why (don't think that anybody missed category D) but I believe that an important reason was the desire to make it easier to compare lists of different European countries. Indeed, it will be interesting to see what will happen...

Andreas Noeske
 ·  25 July 2025  14:08

The last question in the excellent and very comprehensive CDNA-paper is: „15. Wanneer komt Lammergier in aanmerking voor aanvaarding op de Nederlandse lijst? Er zijn een aantal situaties denkbaar waarbij Lammergieren voor aanvaarding in aanmerking komen. Allereerst is bewijs van zwervende Pyreneeënvogels in Noordwest-Europa een aanleiding om het beleid te heroverwegen. Waarnemingen van vogels uit niet-geherintroduceerde populaties in Nederland komen sowieso in aanmerking voor aanvaarding op de Nederlandse lijst. Daarnaast komen wildgeboren vogels uit herintroductieprojecten in aanmerking als ze voldoen aan de door de CDNA gehanteerde criteria voor herintroductieprojecten. Wildgeboren vogels zijn dan aanvaardbaar vanaf het moment dat de geherintroduceerde populatie zelfredzaam en duurzaam is.“ https://www.dutchavifauna.nl/static/publicaties/Definitieve-toelichting-Lammergieren-augustus-2020.pdf

However, 'self-sustaining population' is a matter of opinion and interpretation as is 'wild-born fledglings'. In a fundamentalist's approach it might depend on whether the parents are wild-wild birds or not. Therefore, the Bearded Vulture situation leaves room for many views, even for the rather old-fashioned German categorisation 'BE' and the new Dutch category 'D' as in Doubtful or Dutch, sorry for this;-)

Regarding self-sustaining population and wild hatchlings see: https://besjournals.onlinelibrary.wiley.com/doi/10.1002/2688-8319.12347 and https://besjournals.onlinelibrary.wiley.com/doi/10.1111/j.1365-2664.2008.01585.x

For the time being it seems to be a matter of the committee's administrative policy and taste: some like 'Hollandse Nieuwe', other prefer 'Stroopwafels'.

Only to use both Arnoud's and Peter's wording: Isn't it a bit ridiculous/laughable to have e.g. Buffelkopeend Bucephala albeola on the Dutch list https://www.dutchavifauna.nl/list, but not the Grote Canadese Gans Branta canadensis? This species is, in contrast to Bufflehead, ecologically/economically relevant in the Netherlands:

„So the agricultural damage caused by summer geese has also more than tripled since 2006. The main culprits are the greylag goose, the barnacle goose and the exotic Canada goose. In ten years, numbers of these species have increased by ten times, to more than 250,000 birds.“ cited from https://edepot.wur.nl/454290

„This figure includes the compensation paid for bean-, pink-footed-, brent-, and canada geese damage which is a combined total of approximately 0,5 million Euros.“ see https://cr-birding.org/sites/default/files/Effectivity%20of%20goose%20managment.pdf

The Dutch way seems to be as strange as the German way to put every American sparrow in category D, both are ridiculous.

A matter of taste!

Arnoud B van den Berg
 ·  25 July 2025  14:58

Andreas: you are right, the Dutch system worked until it was decided not to admit Lammergeier to the A-list, despite the arrival of more than a handful of unmarked individuals which, in principle, could have arrived from wild populations further away than the Alpes. Matters got worse when species like Greater Canada Goose and Hooded Merganser were taken out of the A-list. Previously, the system meant that the ‘benefit of the doubt’ was given to any species considered capable of arriving by its own force from a wild origin.

The decisions above and a few other ones (eg, on Spur-winged Lapwing, Pied Crow, Yellow-billed Kite, Grey-headed Swamphen, Japanese Waxwing, Lesser Flamingo and perhaps one or two more) corrupted the system beyond repair, and 'de facto' meant that the committee already adopted the category D system before it was announced and admitted.

Whether or not to ‘count’ category C-species is an entirely different matter; it would have been possible in both systems.

Andreas Noeske
 ·  25 July 2025  19:03

Additional GPS- Lammergieren after 2020 not included in the CDNA-paper and Rare birds in the Netherlands for the years 2021-2023:

There are 17 records of Bearded Vulture listed in the CDNA-paper 'Lammergieren in Nederland en Noordwest-Europa' up to the bird on 30th May 2020 - 13th June 2020, https://www.dutchavifauna.nl/static/publicaties/Definitieve-toelichting-Lammergieren-augustus-2020.pdf

Thereafter in the Rare birds just two birds are listed (Eglazine and Angèle/2021, 0/2022, 0/2023) https://www.dutchavifauna.nl/static/jaarverslagen/CDNA-verslag_2021.pdf. In Movebank https://www.movebank.org/cms/webapp?gwt_fragment=page%3Dsearch_map you can find the routes of three more birds flying over the Netherlands in 2023, none in 2022 (latest update 2025-07-25 12:57:52 for bird Sargas):

ReiDelCausse - Animal Identifier: BV_CAU_2022_JUV_R_3L-_ReiDelCausse, released 09/05/22 in Causses Dourbie ... retrieved weakened in Germany on 27/06/2023, https://www.movebank.org/cms/webapp?gwt_fragment=page=studies,path=study232133400+individual2211551985

Roc - Animal Identifier: BV_CAU_2022_JUV_R_7V-_Roc, released 09/05/22 in Causses Dourbie … collision at wind farm in Netherlands 10/06/2023. body recovered, https://www.movebank.org/cms/webapp?gwt_fragment=page=studies,path=study232133400+individual2211548339

Mojo - Animal Identifier: BV_ALP_2022_JUV_W_03-_Mojo_04, ringed at nest Chambeyron Ubayette 30/05/22 … dead on 29/04/2023, likely killed by a train near Oostvardersplaassen (NL)?, https://www.movebank.org/cms/webapp?gwt_fragment=page=studies,path=study232133400+individual2211566797

How many of the growing number of unmarked birds get undetected?

Leo Stegeman
 ·  25 July 2025  21:04

Here we go again. The conservative opinion is that the new system is corrupted. But so is the old system in other ways. Nobody can claim which one is the best.

For instance to consider all tens of thousands Greater Canada Goose as wild birds because of the remote (but possible) chance that one or two of them are real vagrants, is off course rather ridiculous and far beyond reallity.

Boy Possen
 ·  26 July 2025  10:17, gewijzigd 26 July 2025  10:18

Any system rooted in culture, whether for counting games, social security, government or taxonomy, will inevitably lead to problems. Diversity is inherently problematic for such systems. The question is which kinds of problems and how many we are willing to tolerate.

More importantly, as mentioned above, the CDNA often and, worse, randomly does not seem to adhere to its own guidelines, basing such randomness on flimsy evidence. Rather similar to accusations made towards AviList. This is another cultural problem with diversity that neither system discussed here will solve.

While there is a strong call for more transparency for the CSNA in another discussion, the total absence of such a call for the CDNA is surprising! One cannot exist without the other, as the transparency of the systems we accept is challenged. There should be no problem adding personal votes to a decision publicly if they are made with confidence, for example. This helps to identify problems with a system and can lead to improvements in the way things are done. If we allow improvement.

However, compared to everyday reality, these are luxury problems for most of us. Luckily.

Andreas Noeske
 ·  26 July 2025  10:21, gewijzigd 26 July 2025  10:29

Life history of 'Vinzenz' reported from Groningen in DB Terugblik juni 2025, recaptured exhausted near Bad Zwischenahn/D and back in the Nationalpark Berchtesgaden.

Interesting reading: Flight performance of released bearded vultures 2021-2024

Sorry for interrupting the ongoing discussion!