Particular seasonal abundance of the silvereye (Zosterops lateralis) in autumn of 2024 in the Perth metropolitan area, Western Australia
@hillsflora @george_seagull @lifeisamazing @jeremygilmore
The silvereye (Zosterops lateralis, https://www.youtube.com/watch?v=HHta3iKOiR0 and https://www.inaturalist.org/taxa/202505-Zosterops-lateralis) is widespread in the southwestern part of Western Australia.
The subspecies Zosterops lateralis chloronotus (https://en.wikipedia.org/wiki/Western_silvereye) occurs in the Perth metropolitan area (https://www.inaturalist.org/observations?place_id=19379&subview=map&taxon_id=202505), where I have lived for many years.
My consistent experience in my leafy inner-city suburb, from year to year, has been - based mainly on auditory clues - that the silvereye is only noticeable in autumn.
A particular pattern has been clear to me for decades, and up to the present:
During autumn, I notice the sibilant contact-call of the silvereye in my garden and hereabouts. By contrast, at other times of the year I neither see nor hear the species.
This has seemed to confirm a seasonal movement, in which the population moves through the suburbs - presumably northwards - about the time of the autumn equinox.
In and around my suburb, I have seen the silvereye as the most seasonal of the passerines in the avifauna.
I cannot rule out the possibility that the population is unobtrusively resident, but simply becomes audible and particularly gregarious in autumn.
However, I doubt this, because
- Simon Nevill (2008, https://www.ebay.com.au/itm/335134069071?chn=ps&_ul=AU&norover=1&mkevt=1&mkrid=705-139619-5960-0&mkcid=2&mkscid=101&itemid=335134069071&targetid=1278430613456&device=c&mktype=pla&googleloc=9112576&poi=&campaignid=19649531412&mkgroupid=146789074798&rlsatarget=pla-1278430613456&abcId=9305371&merchantid=7364522&gad_source=1&gclid=Cj0KCQjwwYSwBhDcARIsAOyL0fj84V8Amv4arExKmxibHLRJN8UFWzJxM_0M1hf0Q0m33yivQHyxyOcaAvm2EALw_wcB) has stated that there tends to be a northwards movement of the silvereye in southwestern Australia, after the summer;
- the vocalisation concerned is merely the contact-call;
- migrations northwards in autumn are well-known in eastern Australia; and
- I have never knowingly heard the song ( https://www.google.com.au/search?q=Silvereye+call+audio&sca_esv=82c0c058482216c1&sxsrf=ACQVn0_G2CtHW12KuncPFmobfGn6mGnlMg%3A1710742005946&source=hp&ei=9dn3ZaPoNYmfseMPudCKsAQ&iflsig=ANes7DEAAAAAZffoBQrMhLoUspoVVT9bxocquuv6p_KI&ved=0ahUKEwjjtsDMkv2EAxWJT2wGHTmoAkYQ4dUDCBc&uact=5&oq=Silvereye+call+audio&gs_lp=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&sclient=gws-wiz#vhid=TcEBFkbA0rHZpM&vssid=videos-40363bc1 and https://www.google.com.au/search?q=Silvereye+call+audio&sca_esv=82c0c058482216c1&sxsrf=ACQVn0_G2CtHW12KuncPFmobfGn6mGnlMg%3A1710742005946&source=hp&ei=9dn3ZaPoNYmfseMPudCKsAQ&iflsig=ANes7DEAAAAAZffoBQrMhLoUspoVVT9bxocquuv6p_KI&ved=0ahUKEwjjtsDMkv2EAxWJT2wGHTmoAkYQ4dUDCBc&uact=5&oq=Silvereye+call+audio&gs_lp=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&sclient=gws-wiz#vhid=CAB29XWMX-FVmM&vssid=videos-3efb24bf) of the silvereye hereabouts, suggesting that the species has never bred in or near my garden.
My observations over the years have, thus, been in line with a known pattern.
However, in autumn of 2024, something different has occurred: the seasonal presence of the silvereye has been both accentuated and prolonged.
In 2024, the silvereye first became audible in the first half of March. I then heard it in my neighbourhood on nearly a daily basis for nearly two months.
As I update this Post, it is 11 May 2024, and the silvereye
- remains audible as I write, and
- is still, temporarily, by far the most abundant passerine hereabouts.
What has been unusual in this context is that
- last summer was extremely warm and dry (https://business.weatherzone.com.au/climate/second-hottest-summer-days-on-record-in-perth/ and https://www.abc.net.au/news/2024-03-09/wa-summer-weather-wrap-autumn-outlook/103541460), and
- this weather pattern has continued for an unusually long time into autumn (https://www.theguardian.com/australia-news/2024/mar/01/australia-sweats-through-third-hottest-summer-on-record-with-hot-and-dry-autumn-predicted and https://www.uwa.edu.au/news/article/2024/april/the-big-dry-forests-and-shrublands-are-dying-in-parched-western-australia).
The first rain of the season fell lightly on 30 April 2024. However, as at 11 May 2024, this has not caused the silvereye to depart from Perth yet.
The abundance of the silvereye in Perth this autumn has been remarkable, in apparent correlation with the unusually warm and dry weather throughout southwestern Western Australia.
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