#DuoNat
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cassandroid.substack.com
I didn't even know of this family endemic to Oceania…

I'm playing "Meliphagidae (Honeyeaters)" on #DuoNat — can you tell Brown-headed honeyeater vs Blue-faced honeyeater apart? #iNaturalist
duo-nat.web.app/7q6phe
October 22, 2026 at 4:08 PM
cassandroid.substack.com
check this one too :) duo-nat.web.app/info
DuoNat — Learn to tell species apart
A free game that trains your eye to identify birds, insects, plants and more. Compare photo pairs, learn the field marks, and track the species you've mastered.
duo-nat.web.app
September 13, 2026 at 3:03 AM
cassandroid.substack.com
I love pairs like these :D

First: 'ah, one has a subtle yellow fleck on the wing'

Later: 'oops, one has a black head :P'

I'm playing "Icteridae (Blackbirds and orioles)" on #DuoNat — can you tell Altamira oriole vs Venezuelan troupial apart? #iNaturalist
duo-nat.web.app/uf5881
September 6, 2026 at 2:11 AM
cassandroid.substack.com
I'm enjoying playing "Primates · Asia or Oceania" on #DuoNat — can you tell Lar gibbon vs Siamang apart? #iNaturalist
duo-nat.web.app?pairId=18860...
September 1, 2026 at 2:22 PM
cassandroid.substack.com
first time I learned about the Javan Lutung. Only found around Java.

I'm playing "Primates · Asia or Oceania" on #DuoNat — can you tell Toque macaque vs Javan lutung apart? #iNaturalist
duo-nat.web.app?pairId=30096...
September 1, 2026 at 2:32 PM
cassandroid.substack.com
I'm playing "Placentalia (Placental mammals) · Oceania" on #DuoNat — can you tell Brown hare vs European rabbit apart? #iNaturalist
duo-nat.web.app/0mmx04
August 30, 2026 at 7:06 AM
cassandroid.substack.com
TIL that Aedes + Culex separated before the demise of most dinosaurs (estimated 76 million years ago).

They've been perfecting this for a loong time.

#DuoNat — can you tell Asian tiger mosquito vs Southern house mosquito apart? #iNaturalist
duo-nat.web.app/w2vqpr
August 30, 2026 at 7:51 AM
cassandroid.substack.com
Give this a try :) I wasn't aware that there are SO many owl species before I added them to DuoNat…

I'm playing "Otus (Scops-owls)" on #DuoNat — can you tell Eurasian scops-owl vs Collared scops-owl apart? #iNaturalist
duo-nat.web.app/ucm4me
August 28, 2026 at 6:36 AM
cassandroid.substack.com
lichen lichen lichen!!

lichen lichen lichen lichen!!

I'm playing "Lecanoromycetes (Common lichens)" on #DuoNat — can you tell Oakmoss vs Toy soldiers apart? #iNaturalist
duo-nat.web.app/bhzktt
lichen lichen
August 27, 2026 at 6:26 PM
cassandroid.substack.com
I'm playing "Chironomidae (Non-biting midges)" on #DuoNat — can you tell Psectrotanypus varius vs Paratendipes albimanus apart? #iNaturalist
duo-nat.web.app/7c7qqy
August 25, 2026 at 4:23 PM
cassandroid.substack.com
and yes, they'll be on #DuoNat soon, together with 80+ other Coraciiformes :)
August 25, 2026 at 6:25 AM
cassandroid.substack.com
not really hard once you see it.

I'm playing "Idalus" on #DuoNat — can you tell Idalus daga vs Idalus dares apart? #iNaturalist
duo-nat.web.app/mut37h
August 25, 2026 at 7:23 AM
cassandroid.substack.com
here you go

----

I'm playing "Coraciiformes (Kingfishers, bee-eaters, …)" on #DuoNat — can you tell them apart? #iNaturalist
duo-nat.web.app/tchnmw
DuoNat — Learn to tell species apart
A free game that trains your eye to identify birds, insects, plants and more. Compare photo pairs, learn the field marks, and track the species you've mastered.
duo-nat.web.app
August 25, 2026 at 6:28 AM
cassandroid.substack.com
Two species of no-biting midges. Same family. Separated an estimated 165 million years ago.

Time is deep. Life is vast.

——
I'm playing " #Chironomidae (Non-biting midges)" on #DuoNat — can you tell Psectrotanypus varius vs Paratendipes albimanus apart? #iNaturalist
duo-nat.web.app/7c7qqy
August 25, 2026 at 9:06 AM
cassandroid.substack.com
I'm playing "Idalus" on #DuoNat — can you tell them apart? #iNaturalist
duo-nat.web.app/zpukiz
August 25, 2026 at 2:59 AM
cassandroid.substack.com
I just fell in love with + added 50 Icteridae to #DuoNat :) #birding #birds
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I'm playing "Icteridae (Blackbirds and orioles) · N. America" on DuoNat — can you tell Melodious blackbird vs Montezuma oropendola apart? #iNaturalist
duo-nat.web.app/mxt8dh
August 24, 2026 at 5:06 PM
cassandroid.substack.com
great vernacular name!

'hey, which of the genus with the name »yellow bird« in the family that has lots of yellow birds do you mean?'

'THE YELLOW ONE'
gallery of genus 'Icterus' in DuoNat. circled: I. nigrogularis. you know, the yellow one.
August 24, 2026 at 6:41 PM
cassandroid.substack.com
I just learned "Chromodoridoidea · Species" on #DuoNat — 97 taxa. Can you do it too? #iNaturalist
duo-nat.web.app/otvf7d
August 24, 2026 at 1:04 AM
cassandroid.substack.com
Can you tell Macfarland's chromodorid vs Harlequin sea goddess apart? #DuoNat #iNaturalist
duo-nat.web.app/p5l7aq
August 20, 2026 at 5:42 PM
cassandroid.substack.com
Can you tell The rustic vs Vine's rustic apart? #DuoNat #iNaturalist
duo-nat.web.app/jc8r15
August 20, 2026 at 10:10 AM
cassandroid.substack.com
TIL that fern genus Adiantum dates back ONE HUNDRED FIFTY MILLION YEARS

*mind blown* - that's when the common ancestor of whales + us looked like shrews

Can you tell Walking maidenhair fern vs Diamond maidenhair fern apart? #DuoNat #iNaturalist
duo-nat.web.app/ebi6aj
August 19, 2026 at 12:37 PM
cassandroid.substack.com
It's the ears :P

Can you tell Southern elephant seal vs Steller Sea Lion apart? #DuoNat #iNaturalist
duo-nat.web.app/0lz4an
August 19, 2026 at 6:19 AM
cassandroid.substack.com
Can you tell Even-toed ungulates, … vs Odd-toed ungulates apart? #DuoNat #iNaturalist
duo-nat.web.app/cvjfei
August 18, 2026 at 12:19 PM
cassandroid.substack.com
Have a go at distinguishing them from others on #DuoNat :)

duo-nat.web.app/quyi9n

I'm personally *really* struggling with shorebirds… they're all the same picture :P

#iNaturalist
all pairs you can play in this set. Western Shorebird is pinned. check "How to use" in the help menu for details. Message me for feedback, this is still in beta.
August 18, 2026 at 3:47 AM
cassandroid.substack.com
learn Spanish with #DuoNat :)

duo-nat.web.app?pairId=59216... #iNaturalist
August 17, 2026 at 12:47 PM