Birds and Mice in the Grampians

February Saturday 21st 4pm

FOGGs donated some money to the Museum of Victoria some time ago to help with student research projects. Phoebe Burns and Kara Joshi are a couple of these students, working on Smoky Mouse and bird detection. They came and presented their findings to a good group of FOGGIES and other interested locals.

BIRD DETECTION METHODS

Kara’s presentation was on her work trialling a new bird detection method using an audio recorder. Currently bird surveys are carried out by live humans listening to, and looking for, birds out in the field. It is usually very accurate, but time consuming and depends on people having easy access at suitable times of day. It is hard to make it comprehensive and unbiased. Is there a way to use the technology of recording bird calls and then machine reading them? Kara set up recorders and got many hours of bird calls, then ran them through the computer to see if she and it could separate the different bird calls and identify them. She also got bird experts to listen, and compared their results with those of the computer. Unfortunately she found that it was much harder than it sounded. Eventually it probably will work, but for the present nothing replaces a birdwatcher with binoculars and good ears.

This is one of those research projects that it is really useful for us to support. It’s not a sexy or exciting topic, but it lays the groundwork for what could be a very useful tool in the future. Just think of what a revolution the use of remote cameras has been for our knowledge of small mammals in the park.

SMOKY MICE IN THE GRAMPIANS

Phoebe has kindly sent us her summary of her talk.

Phoebe Burns is a PhD student at the University of Melbourne and Museum Victoria. With the assistance of a research grant from FOGG, Phoebe recently completed a Master of Science (Zoology) focusing on the status of smoky mice in the Grampians in light of forty years of droughts, invasive predators and fire.

The endangered and elusive smoky mouse (Pseudomys fumeus) is a small native Australian rat species. The nocturnal species nests in communal burrow systems and consumes a varied diet of fungi, invertebrates, seeds and plant material. While many aspects of the species’ life history appear quite flexible – such as diet, habitat, and timing of the breeding season – smoky mice have been poorly detected across much of their range in recent decades and are thought to be in decline.

There are several hypothesised causes of decline in smoky mice, most notably drought, foxes, feral cats, and fire – all of which play major roles in the Grampians-Gariwerd National Park. My research focused on a smoky mouse population in the Victoria Range, in the west of the park. In November 2012, I was part of a team from Museum Victoria and Parks Victoria who surveyed one of the historical smoky mouse sites in the Victoria Range as part of a broader survey of the Grampians. We detected an astounding 28 individuals at the one site, now affectionately known as ‘Supergully,’ – a record high number in the Victoria Range. Three months later Supergully burned in the Victoria Valley fire, along with all other historical smoky mouse sites in the Victoria Range.

Given the severity and comprehensiveness of the fire, our main concern was that if smoky mice could not persist in the fire scar, there might be no suitable unburned patches nearby from which they could recolonise the Victoria Range. Many small mammal species in the Grampians, such as swamp rats and heath mice, aren’t found within fire scars for a few years post-fire. Based on smoky mouse records in the area and the documented fire responses of similar species, the outlook for smoky mice was grim.

I set out to determine whether smoky mice had declined in the Victoria Range since their initial detection in 1974 and how the species responded to the 2013 fire. From September – December 2013 I surveyed 42 burned and unburned sites across the Victoria Range.

Prior to this study, smoky mice were recorded in the Victoria Range in two sites in 1974 and three sites in 2002-4. In 2013, I detected smoky mice at one known site and five new sites, although I also confirmed their absence from the only two sites where the species was detected in 1974. The limited number of sites surveyed in 1974 and the gap in surveying between then and 2002 mean that although there has been no statistical shift in occupancy over the past 40 years, I cannot confidently interpret this in practical terms. Although I detected individuals at ‘new’ sites, this may be a reflection of previous sampling effort rather than a shift in the species’ occupancy in the Victoria Range.

Contrary to expectation, smoky mice survived in the Victoria Valley. Of the six sites at which I detected smoky mice in 2013, five had recently burned. Of nine individuals I captured at Supergully in 2013, three were recaptures from 2012, suggesting the species persisted in situ. All the individuals I captured at burned sites were within a normal weight range and I found evidence of breeding. While this is great news for smoky mice, the species may not respond in the same way to future fires under different weather and habitat conditions.

Despite persisting through the fire, smoky mice appear to be currently declining in numbers in a snapshot of one site. Supergully yielded 28, 9 and 3 individuals in 2012, 2013 and 2014 respectively. This may be a delayed response to the fire, part of a natural population cycle, or the result of some other factor such as decreased rainfall.

Smoky mice in the Victoria Range have persisted over the past forty years of droughts and feral predators, as well as the short-term impacts of fire. However, for smoky mice and other threatened species, we need to survey populations regularly to keep track of fluctuations in abundance and isolate these from other threatening declines.

 

If you have knowledge of any smoky mouse records from across Victoria that may not have been published, please contact Phoebe at:

 


Both girls joined us for a meal at Halls Gap pub and a pleasant discussion.

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