Zosterops spp. (whiteyes and silvereyes, https://www.inaturalist.org/observations?place_id=any&subview=map&taxon_id=17439&view=species) are odd in several ways.
They are
Crucial is the observation that Zosterops oddly combines a brush-tipped tongue with a short beak (https://www.perplexity.ai/search/Please-list-all-P5272Q3URqe3IcoI547GAg).
In this Post, I introduce the idea that the original evolutionary strategy of Zosterops was to be simultaneously
Most small birds participating in ornithophily have long beaks (https://pubmed.ncbi.nlm.nih.gov/36062802/ and https://evolution.berkeley.edu/convergent-evolution-its-for-the-birds/). These are inefficient for gleaning homopterans.
Furthermore, aphids tend to be scarce
In Australia, aphids are generally replaced by psyllids (https://en.wikipedia.org/wiki/Psyllid) and other armoured forms of sap-sucking Hemiptera (https://en.wikipedia.org/wiki/Hemiptera), predated mainly by small passerines with specialised, broad beaks (https://en.wikipedia.org/wiki/Pardalote and https://en.wikipedia.org/wiki/Weebill).
Long-beaked, nectarivorous birds do take remarkably small insects routinely, but mainly by hawking (https://en.wikipedia.org/wiki/Hawking_(birds) and https://researchportal.murdoch.edu.au/esploro/outputs/other/The-possible-ecological-significance-of-hawking/991005541828107891 and https://www.researchgate.net/publication/283793917_Ecology_of_Honeyeaters_Meliphagidae_in_Western_Australian_Eucalypt_Woodlands_I_Resource_Allocation_Among_Species_in_the_Great_Western_Woodland_During_Spring and https://www.sciencedirect.com/science/article/abs/pii/S0003347205802295).
I suggest that Zosterops has evolved essentially as a consumer of, simultaneously,
From this origin, Zosterops has been able
The various adaptations of Zosterops have been mainly behavioral, not morphological: it has retained small body size and a consistent shape (including the beak), while being versatile in other ways. The genus has applied a single body-form to various niches, in an 'evolutionary radiation' antithetical to the classic example of modification of body-form in Darwin's finches (https://en.wikipedia.org/wiki/Darwin%27s_finches).
Given that its taste for sugars was originally oriented towards honeydew, the taking of fleshy fruit-pulp and -juice by Zosterops can be interpreted as opportunistic rather than central to the evolutionary strategy.
This in turn helps to explain why Zosterops has remained small-bodied relative to most coexisting birds that eat fleshy fruits, forgoing many fruits too large for it to swallow whole.
In particular, Zosterops varies in
In southwestern Western Australia, the subspecies Zosterops lateralis chloronotus (https://www.inaturalist.org/posts/91030-extreme-seasonal-incidence-of-the-silvereye-zosterops-lateralis-chloronotus-in-autumn-of-2024-in-the-perth-metropolitan-area-western-australia-in-response-to-heat-and-drought) naturally had a habitat - throughout the year and regardless of its partial latitudinal migration - virtually devoid of aphids. I refer to the situation before aphids were anthropogenically introduced to Australia, and inadvertently promoted by horticulture, agriculture, and the application of fertilisers.
Here, it has applied its brush-tipped tongue to the extrafloral nectaries of Acacia (https://www.researchgate.net/figure/Extrafloral-nectaries-EFNs-are-universal-on-the-leaves-and-phyllodes-of-SouthWest_fig16_276919754).
In Hawaii, aphids and ants - and Zosterops - were naturally absent from the indigenous biota (https://www.perplexity.ai/search/Which-genera-of-oM7eVb_fTQyunhB_CqpaRw). The extreme success of the anthropogenic introduction of Zosterops to this archipelago has probably been facilitated by the introduction of the insects and plants necessary to establish the mutualism that produces honeydew.
To what degree has Zosterops adapted to the anthropogenic introduction of aphids in Australia, by eating these insects?
https://animaldiversity.org/accounts/Zosterops_pallidus/
https://www.perplexity.ai/search/In-which-ways-hUmRnLf5Ry2CWdzouOK9_A
to be continued in https://www.inaturalist.org/journal/milewski/95204-a-new-interpretation-of-the-evolutionary-and-ecological-strategy-of-whiteyes-and-silvereyes-zosterops-part-2#...
Comentarios
https://fatbirder.com/ornithology/promeropidae-sugarbirds/
https://en.wikipedia.org/wiki/Sugarbird
https://www.sciencedirect.com/science/article/pii/S0960982221011222
https://set.adelaide.edu.au/news/list/2021/08/23/how-did-sugar-eating-birds-co-evolve-with-plants-that-produce-nectar
https://www.sciencedirect.com/science/article/pii/S2351989417300860
https://repository.naturalis.nl/pub/317693/ZV1969102001.pdf
https://www.researchgate.net/publication/303667734_Extrafloral_nectaries_in_an_Australian_rainforest_-_structure_and_distribution
https://www.publish.csiro.au/sb/Fulltext/sb19012
https://www.jstor.org/stable/2996000
https://www.perplexity.ai/search/How-many-genera-IV.YsOjQTciC0sCLs1P70A
https://www.perplexity.ai/search/Which-indigenous-plants-JZM0bdXGTXykpNxvK47jvw
https://fatbirder.com/ornithology/zosteropidae-white-eyes-yuhinas-and-allies/
https://ap-st01.ext.exlibrisgroup.com/61MUN_INST/upload/1717044213072/bird_species_richness_and_community_structure.pdf?Expires=1717044333&Signature=DR4Vp91-onJURAigPZgtGmcGkKGfXQA91vlo2YHEaw8vCBym3~xEJdmIuS4VFghC8uZfJFF6kMOQ~JbyOhGX1ouRrV~zTrcbuqMkmHxdkeg9v-Mc8XArcE6yzCssSDVz6j52rB601Aol4TEu-y2StKBawnx3xQkmBUvDGW6wsJICH0jnVy76A6YXvat7cnhCP8aloqHhtauEQlweRbbuOzf4G0rwiIvREDKIsTixePWPOJl9PKLzrfB7eWlHycNQmCRZs02XfLOTozzC75we-eOdU1~xtODshv1Q4DLKzwFPVqm2RPCWZfsBoKk3HvJ-Wv6XJqC~KIXJcTlfvxEcug__&Key-Pair-Id=APKAJ72OZCZ36VGVASIA
https://www.perplexity.ai/search/Which-indigenous-plants-JZM0bdXGTXykpNxvK47jvw
https://www.lauraerickson.com/bird/cape-may-warbler/
https://www.perplexity.ai/search/Zosterops-combines-small-uDAqQVqrRCKXiSrqADHi5g
Evidence that Zosterops eats aphids:
http://www.thegardeningblog.co.za/gardening/sunbird-in-the-hibiscus/
A relevant family and genus are Pipridae: Pipra, which are restricted to tropical America.
https://en.wikipedia.org/wiki/Pipra
These birds are noteworthy for combining small body size (9-10 cm) with the consumption of fleshy fruits as a staple diet.
https://www.perplexity.ai/search/Do-birds-in-eIryQ475SV.yCs7s37yRXA
Dicaeidae: Prionochilus
9-10 cm
7-23 g
brush-tipped tongue
BUT
beak short but broad
crucial relationship with Loranthaceae (https://en.wikipedia.org/wiki/Loranthaceae)
https://www.inaturalist.org/observations?taxon_id=13444
Confirmation of participation by Zosterops in mixed foraging flocks:
https://researchonline.jcu.edu.au/58215/1/Wilson%202018%20Mixed%20bird%20species%20flocks%20Kuranda.pdf
https://www.perplexity.ai/search/In-many-parts-nRrrg4ENTlCyvoVwamagNQ
https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2435.14540?af=R
https://www.researchgate.net/publication/378969079_Differences_in_mixed-species_bird_flocks_across_forest_succession_Combining_network_analysis_and_trait-based_ecology_related_to_the_fast-slow_continuum
APHIDS IN THE DIET OF HUMMINGBIRDS?
https://gardenmentors.com/garden-help/wildlife-2/hummingbirds-eat-aphids/
https://www.perplexity.ai/search/Is-any-species-ykIdzu7KSDW.GgfAaAuECQ
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=29582
My commentary:
I see the reply by Perplexity AI as being confirmation-biased, in the sense that a) only one of the references cited actually supports the idea that aphids are an important part of the diet of hummingbirds, and b) this reference is merely an informal, semi-popular note in the context of gardening.
DICAEUM
tubular tongue
https://www.inaturalist.org/observations?taxon_id=13375
https://www.researchgate.net/publication/338803489_A_checklist_and_host_catalogue_of_the_aphids_Hemiptera_Aphididae_held_in_the_Australian_National_Insect_Collection
https://www.riverbanks.org/subsite/pact/whiteeyes.pdf
https://www.jstor.org/stable/25511588
https://avithera.blogspot.com/2014/04/silvereyes.html
Zosterops eating fleshy fruits of Exocarpos and Hymenanthera
An example of the behavioural versatility of Zosterops:
Zosterops lutea, a species associated with mangroves, has minimal fleshy fruit in its diet. Ref: Atlas of Australian Birds.
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