Sector 8 survey; some WEIRD behaviour

During the 11th November survey, I witnessed one of the strangest behaviours I have even seen in the field. I recorded an interaction between a Brown Thornbill and a female Variegated Fairy-wren. My initial reaction was that the Variegated Fairy-wren ‘supplanted’ the Brown Thornbill; supplanting is where a species displaces another species from its perch, i.e., I run toward you and scare you off your seat and take your seat. HOWEVER, I noticed afterwards that the Fairy-wren persisted for over 2 minutes with this apparent aggressive behaviour toward the Brown Thornbill. Let it be known at this point, that the fairy-wren is perhaps one of the most placid of any species and rarely exhibits any form of aggression to any other species (interspecific), or even to members of its own species (intraspecific; apart from that associated with breeding I suppose). Anyway, it was after 2-3 minutes of watching this interaction that I recorded the most bizarre behaviour: the Brown Thornbill turned and fed the fairy-wren!! This is unprecedented! Apart from observations of small birds feeding cuckoo chicks (for those not aware, cuckoos only ever lay their eggs in the nest of other species, so a small little bird feeding a great big cuckoo is not all that uncommon), interspecific feeding is incredibly uncommon!

So how can we explain this bizarre behaviour? Well, there is one possibility that I can think of, and it relates to the fact that fairy-wrens live in (often) large groups; usually with more females than males. Young females usually disperse away from their ‘birth’ place the year after they fledge, and therefore look for mates outside their natal territory. It is possible however, that the young fairy-wren female, having no doubt been harassed by her mum or other dominant female to leave the territory, has decided to remain. Without an available mate (or dominant female allowing her to mate with the male/s in the territory) her cluckiness has led her to find another bird, perhaps similar looking, to be the object of her desire. What reason the Brown Thornbill has to feed her however, I will never know. It is possible that the Brown Thornbill is also an unwanted individual, so likes the company that the female fairy-wren provides…….. Anyway, there is an interesting story I am sure you will agree!!

I have included a pic of the male Variegated Fairy-wren, as he is much more striking in colour than the female!! Now on to the sightings!!

Date: 11th November 2008
Time: 0530 - 0732
Sector: 8
Number of species seen: 16
Number of birds seen: 149

Australian Brush-Turkey (1)
Black-faced Cuckoo-shrike (1)
Brown Thornbill (3)
Eastern Yellow Robin (2)
Grey Butcherbird (2)
Australian Magpie (3)
Noisy Miner (32)
Olive-backed Oriole (1)
Pied Currawong (1)
Rainbow Lorikeet (20)
Scaly-breasted Lorikeet (35)
Silvereye (8)
Torresian Crow (3)
Variegated Fairy-wren (27)
White-browed Scrub-wren (6)
Yellow-faced Honeyeater (4)