March Meeting

Wed 08 March 2023 07:30pm

Silvia Colombo - Evolutionary drivers and thermal consequences of nest architecture in birds
Sue Beatty - Extreme Birding on Cocos Island
Michael Guppy and Peter Fullagar
- An Analysis of the Dawn Chorus Song of a Male Grey Shrike-thrush

The March meeting will be a normal face-to-face one held at our usual venue. Attendees should heed social distancing and good hygiene practice etc, and use their common sense and stay home if they have COVID symptoms. Mask wearing is recommended.

This month there will be 3 presentations expected to take up the same time as the usual short and main talks.

The first presentation will be by Silvia Colombo, a Ph D student at the University of Melbourne and a recipient of funding from the Canberra Bird Conservation Fund with the title: Evolutionary drivers and thermal consequences of nest architecture in birds.

Nests evolved in birds to create a suitable environment to lay eggs and raise nestlings. Building an appropriate nest structure that can protect from environmental conditions and harsh ambient temperatures is a fundamental behaviour that increases offspring survival. We still ignore the drivers underlying the global evolution of nest architecture as well as the variables driving the transition from domed to open nests. We aimed to investigate whether nests with a roof (domed nests) (i) evolved as an adaptation to extreme temperatures, (ii) offer different thermal environments compared to open nests, and (iii) have specific traits that make them better adapted to extremely cold or hot arid environments. We collected data on nest microenvironment in domed and open nests in Campbell Park, Canberra. We opportunistically included all the open and domed Passerines nests available during the breeding season belonging to the following species: Weebill, Grey Fantail, Willie Wagtail, Yellow-rumped Thornbill and Superb Fairy-wren. This project is expected to allow us to understand how nest architecture can protect eggs in a future scenario of harsh temperatures caused by contemporary climate change.

The second talk will be by Sue Beatty on the “Extreme Birding on Cocos Island”, the second half of her February presentation on her recent trip to Christmas and Cocos islands.

Michael Guppy and Peter Fullagar An Analysis of the Dawn Chorus Song of a Male Grey Shrike Thrush (Colluricincla harmonica).

The vocalisations of the Grey Shrike-thrush are loud, clear, pleasing to the ear, and a stand-out feature of the bird song in areas in which they occur. However, almost nothing is known about the character of this very obvious song. We have made some recordings of the dawn song of a male individual down near Moruya. The song comprised discreet groups of notes which we call syllables. The syllables are sung about every 5-10 seconds, and the individual produced 20 different syllables over the course of the eight recordings. Various analyses revealed that new syllables were added gradually over the recording period. The frequency of use of particular syllables varied markedly, it was common for some syllables to be used as repeats, particular syllable couplets were commonly used as alternations, and the sequence of syllables could be remarkably similar between different recordings. We suggest a way forward to determine whether these patterns are a common feature of the vocalisations of this species.

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