Declaring a bird extinct: The median wait is 36 years after the last sighting
birdshistory.com
birdshistory.com
In Australia, well the north part of Queensland at the very least, since the 80s there's really not been that much funding or an obvious program of population monitoring of whatever native species remain, including birds.
I miss what used to be common bird calls from my youth even though I didn't know which bird species was responsible. I've resolved the mystery for a couple I could recall but one still eludes me. In my parts the high canopy tropical forests have taken a huge toll from the 90s, no real wet season with warm rain, no large storms, (these days it's not uncommon to hear alarm around a storm dropping 3 inches in a couple of hours ... used to have years where they were not uncommon,) a fungus pathogen taking out some trees which may just be down to the trees being stressed more than their evolution allowed for - oh yes, the fact that many summer storms on their westerly approach had started to hesitate on a direct track over the coastal areas might just boil down to the man made heat bubble with open cut coal mining and the large areas as per mining which now have no to little vegetation.
Some females laid on the nest rim and lost the egg, whichEveryone assumed was a learned habit... a 2013 pedigree study found it was a dominant allele from one of the founders!
That managers rescuing the eggs is what let it spread. So not a new subspecies, but a genetic sliver of what used to exist -- carrying whatever the founders happened to carry.
On Queensland — the paradise parrot is the only extinct mainland Australian bird, last seen around Gayndah in 1927–28. The only photos of a live one were taken by a grazier from a hide made of old bagging in 1922.
What I was thinking of was more along the lines where after a species faced extinction, what survived was due to slight genetic variance that in time the more successful would continue to push the more purposeful genes to adapt to the changes inflicted onto the area they inhabit or migrate more. I am of course not saying this is the instance in every population wipe out and re-emergence, I can point to instances where a simple change of behaviour comes down to learned behaviour, such as what happened with the introduction of cane toads and wildlife including birds learning how to eat the mongrels (carefully.)
The Paradise Parrot I would guess succumbed to the introduced rats ... and given their ground dwelling and termite nesting would have later faced the feral cat explosion. It is a pity.
I suspect in my immediate location only a couple of miles from a large forested area that was never heavily logged and now protected, that a small handful bird species remained unrecorded even if they were recognised by some common name by the immediate locals. The one bird species I'm still trying to identify had a simple call of individual loud chirps from high in octave to low and then half repeated from mid octave - it seems terribly unfamiliar to any one I've asked who I'd expect is familiar with all of the regions birds.
[1] https://en.wikipedia.org/wiki/Black_robin
"... leading to speculation that the species has passed through several such population reductions in its evolutionary past, and has lost any alleles that could cause deleterious inbreeding effects"
https://thememorypalace.us/the-woods/
The red shock of feathers on the heads of the males,
the bright white that spilled down the sides of the long throat to pool in the center of the wide wings,
hemmed in by borders that looked jet black in pictures,
but in real life were something other.
A glinting thing.
A blue-purple.
A night sky.
On the right night.
https://web.archive.org/web/20261004025452/https://birdshist...
[1] https://economictimes.indiatimes.com/news/international/glob...
[2] https://greatergood.com/blogs/news/mosquitoes-in-hawaii (mosquito population reduction project )
What surprised me is how cleanly disease sorts by place. All nine disease cases are Hawaiian, and all nine Hawaiian species are disease cases. One-to-one, no overlap in either direction.
Rats and cats show up hardest in the flightless birds, and they got there early. The flightless species in the set have a median last record of 1662, against 1946 for the ones that could fly - and nothing flightless has a last record after 1899.
The Wolbachia work is further along than most people realise: drone delivery on Maui from April 2025, past 40 million males released by mid-2025.
Method, since the number deserves scrutiny: the dataset is every bird on my site where both dates are documented, the last confirmed record (specimen, photo, recording, accepted sighting, or death of the last captive) and the first formal extinction declaration by a recognised authority. That gives 13 species and subspecies. Median gap 36 years, mean 47.5, range 3 to 124.
Two rules matter for reading it. Where a bird was declared twice (IUCN and later the US delisting in October 2023), the earlier declaration counts; using the US dates would inflate most figures. And the sample is small and weighted toward Hawai'i, so the median describes these birds, not a published constant.
The pattern that seemed most robust to me: the three short gaps are all birds whose last individual was watched dying, e.g. the dusky seaside sparrow in captivity in 1987, declared in 1990. Where the record just stops, nobody can date the stopping, and the declaration takes decades.
Happy to go into the sources or any individual case.