eBird rarity - what are the criteria?

[Mike Bickerdike]

I get eBird rare bird alerts, which I find helpful. However, I'm not sure what the criteria are that define rare. Can anyone help explain, and is the list of birds that count as rare revised or managed manually in any way, or is it simply dictated by an eBird algorithm?

I ask as I've seen bird examples that fall either side of inclusion recently: black-tailed godwit doesn't show in rare bird alerts, though observations of them are quite notable and it would be helpful I'm sure, whereas bellbirds seen in the Hanuas do show in the alerts (although I think they are not rare there).

[Jan]

Hi Mike I've sent you an email with a thingy for rare birds, not for eBird, but it may help

[Mike Bickerdike]

Thanks Jan. no email received im afraid. I’m only interested in the eBird definition of a rarity for alert purposes though (and how it is moderated).

[Brendan T]

I'm also interested in better understanding this.

From chatting to people in Aus who have been involved in reviewing at the LGA level, my understanding is that eBird defines a Rare bird as anything that the filter is set to "0" on for a particular region (in other words, high counts won't trigger - just species for which even one of its kind would be considered unexpected - in theory, that is). I believe this filter is affected by the historical data, which helps form some sort of baseline, yet this baseline can also be manually tweaked (and may needed to have been manually created, too).

For example, the filter for most LGAs in the Hunter, NSW, had White-throated Gerygone set at "0" for the month of April onwards due to historical data, but this was tweaked manually to now be set at "0" from May onwards to better reflect the reality of lingering birds, despite most having already moved on by April. Of course, for some birds, the filter will be set to 0 no matter the time of year.

But eBird is full of little quirks, especially at the subspecies level, despite the dedication of some amazing people to keep it all running - e.g. getting rare bird alerts for New Zealand Dotterel (Northern) or Sacred Kingfisher (New Zealand), which wouldn't happen if the species were simply reported as Northern/Southern New Zealand Dotterel or Sacred Kingfisher. Even though I found the Piako Blackwit, it's something that I would have very much wanted an alert for if it had been someone else to find it, yet I'm not too interested in a Bellbird sighting in the Hunuas (much like you, and probably others, too).

That's just a few random examples to help illustrate it. I'm far from aware of all the ins and outs. But I think the answer essentially boils down to volunteers having limited time, and/or the filters existing for a slightly different purpose than we use them for?

[Jan]

You should get the email, Mike. It hasn't bounced.
maybe gone to spam as might not have had a subject?

I'm not that knowledgable about how eBird works but I gather people at Cornell in USA are in charge and apply filters to get as much coverage as possible, not necessarily as accurate at a local level as you would like. Nick Allen has posted about this a fair bit so maybe search for his posts?

[paradoxdinokipi]

Filters are applied by regional reviewers/local volunteers, a list of filters for regions globally can be found here: https://review.ebird.org/admin/filterList.htm?all=true
From here you can search for finer regions, eg Auckland (specifically here South Auckland which includes the districts of Franklin, Manukau City & Papakura): https://review.ebird.org/admin/viewFilt ... ID=CL22876
The fact that Australian Shelduck doesn't flag as 'rare' and only 'trips the high count' when more than 1 are reported has always bugged me, 'peep sp.' flagging at 3 I also find a bit odd, some of the other waders I also question the filters a bit (eg. SSP, GSP, Terek, Far-Eastern, Pectoral & Common), whilst some of these may genuinely be annual [I feel some of the counts may reflect the past where there were just more waders around? But can't say I know that for certain], I believe a few of the counts that are 'allowed' are a bit high and more stringent filters usually led to better reporting by eBirders and less likelihood of odd records slipping through the gaps.
Of course this is all volunteer work and I do applaud the effort that has been put in, I just wouldn't mind more volunteers helping 'patch up' anything else.

[Mike Bickerdike]

Thanks for the ongoing discussion. It maybe looks as though there could perhaps be some updating and refining of the criteria, but as others have said, I appreciated it all done on a volunteer basis.

Even though I found the Piako Blackwit, it's something that I would have very much wanted an alert for if it had been someone else to find it, yet I'm not too interested in a Bellbird sighting in the Hunuas (much like you, and probably others, too).

Like many, I benefit not only from eBird alerts, of course - the 'grapevine' on FB and on this forum is also invaluable - as demonstrated by your own prompt report of the blackwit Brendan, which enabled me to go and twitch it. I guess if we combine the different resources we can catch most things...

[Bobolink]

I'm just baffled how species such as Eurasian Curlew, 1986 https://ebird.org/checklist/S131343610; Wedge-tailed Eagle 1979 https://ebird.org/checklist/S77977518; Common Tern 1977 https://ebird.org/checklist/S77499795; Sooty Albatross 1976 https://ebird.org/checklist/S23957233; Red-footed Booby 1974 https://ebird.org/checklist/S23517315; Tahiti Petrel 1973 https://ebird.org/checklist/S23517249 and Common Ringed Plover 1970 https://ebird.org/checklist/S26767356 (SemiP?) have escaped the attentions of the reviewers.

[Jan]

Hi George, those are very old records. There may not have been reviewers that long ago, and they are all volunteers even now. Cornell should have picked those up in any case, but probably didn't think they helped the overall distributions they want?

[Bobolink]

Hi Jan the records were put on recently as historical records. Hopefully now they have been flagged something will be done. (Before you say, I've tried several times to become a reviewer but with no luck). Cheers George