Article by Tyron de Kauwe, Natural Areas Conservation Officer, Sunshine Coast Council
Welcome back for another edition of flying-fox community news.
In the September edition I mentioned that this was the usual birthing season for the grey headed and black flying-foxes. During routine monitoring of roosts in October, dependent young were recorded at Andrea Ahern Park (Battery Hill), Kuluin Neighbourhood Park (Kuluin) and Pecan Park (Maleny).
When flying-foxes give birth, the mothers remain at the site until the young become independent, around February. The pup clings to its mother’s belly for the first three to six weeks and feeds on her milk for five to six months.
After six weeks, the pups are left together (like a day-care) in the roost while their mother looks for food throughout the night. When she returns, she recognises her baby by its call. This is why a higher trill can often be heard in sections of a roost. From three months, young flying-foxes can fly short distances. From five to six months they are able to feed independently.
During the first three months, young flying-foxes cannot move themselves from perceived danger and can be abandoned by their mother if stressed. Sunshine Coast Council, where possible, avoids management actions during this critical period.
Flying-foxes also have a high fidelity to maternity sites and generally return to the same sites to give birth in consecutive years. It is expected that young will be seen in other traditional maternity sites soon too.
‘Bat-packer hostels’ and nature’s greatest nomads
It is common knowledge that flying-foxes are capable of sustained flight and they can travel over large distances each night in search of food. Did you know that they also travel large distances each night and move to different roost sites?
Avid readers of my previous articles may have come across my use of the term ‘bat-packer hostels'. I use this term to describe how flying-foxes use roosts across the landscape. Like back-packers, flying-foxes move across the country and spend short periods of time at a roost before moving onto the next site, all the while following flowering patterns.
A recent study tracked 201 flying-foxes over the last five years to determine how far they travel. I will highlight a few of the results that show how nomadic flying-foxes are. If you would like to know more, see the ABC interview with the author.
It is easy to think that when you see flying-foxes roosting near you, that they are the same individuals each day, but that is certainly not the case. When black flying-foxes are in a roost site, 11.9% of them will change sites daily. These numbers are even greater in other species found on the coast. 17.5% of grey headed flying-foxes change sites each day and a staggering 36.4% of little red flying-foxes shift sites daily.
This is why old fashioned management methods like dispersals don’t work. When flying-foxes are scared off from a roost, the next day up to a third of flying-foxes from other sites will potentially move into the dispersal site, with no experience of the dispersal. This occurs every day across Australia and it is fairly obvious to see how dispersal would be required every day. This is one of the main reasons why dispersal is not a feasible action. It also accounts for why sometimes sites can experience a large boom in numbers seemingly overnight when there is a lot of food around.
But how far are they traveling?
This is where management gets tricky and why actions are always looked at for their impacts across the region, rather than individual/separate sites that can be managed alone. This study found that flying-foxes tracked from eight sites used a total of 755 different roosts, and 458 (61%) of those had not been recorded before.
When moving between sites, some black flying-foxes flew up to 92 km in one night to get to their next site. This is nothing compared to some reds that flew 162 km or greys that flew up to 270 km in one night to get to the next roost! On average, greys will fly over 1,500 km per year moving between roost sites—that doesn’t include their nightly travels to find food either.
There are always overachievers though. One grey was tracked for 1,629 days (almost 4.5 years) and in that time it covered 12,337 km and moved between 123 roosts spanning from Melbourne to Central Queensland. To put this into perspective, this frequent flyer moved between 37 different council areas or 21 Federal electorate zones. This shows how complex management actions are for flying-fox roosts. Actions from councils two states away can have ripple effects on what is seen locally.
Get involved in flying-fox research
It is very difficult to manage flying-fox roosts because flying-foxes constantly move in search of food and may already be in areas that no one has reported before. Therefore, the long-term goal of council is to identify suitable habitat in low-conflict areas outside of the urban footprint and improve them by providing more food trees and rehabilitating the bush so flying-foxes are encouraged to roost there. If the areas they want to roost are away from the urban area, there will be far less conflict.
This is where you come in.
We have partnered with the University of Melbourne to hold a Citizen Science weekend on 28 and 29 November. We are seeking people across the region to help us collect data.
Like the popular “Birds in Backyards” week, we are after people to record when and where they see flying-foxes feeding at night.
By understanding where they are feeding and what they are feeding on, we can then identify important food hotspots, that could be near suitable habitat. We can also determine what mums are feeding on while raising their young, to help establish suitable maternity roosts.
Bats in Backyard
28 - 29 November 2020
Where: Wherever you are. You can do it from home, or you can go for a walk and record where they are feeding in your area
View our information sheet for more details.
Heat Stress potential
Being dark, furry and hanging from the treetops has some disadvantages. The most notable is being vulnerable to heat stress events as the weather warms up.
In November 2018 a heatwave hit Cairns, causing the death of 23,000 spectacled flying-fox. This was just under one-third of the total national population. South-east Queensland has also experienced mass mortality events. Over 45,000 flying-foxes dying when temperatures exceeded 42oC back in January 2014.
There are response protocols in place to monitor and intervene during these events.
The heat-stress forecaster is used to get advanced warning at sites and allows time to co-ordinate on-ground responses. Unfortunately, the hardest part is that many roosts can be affected at once and requires a response at multiple locations.
When onsite, experts observe the behaviour of the flying-foxes to determine their stress level and if intervention is required.
Here are a few things to keep in mind around flying-fox roosts this summer:
- Flying-foxes flap their wings to help cool down. If you see them up in the canopy flapping away, they are not currently stressed, this is the earliest stage of cooling and they do not require assistance.
- Stressed flying-fox mothers may abandon their young, so do not disturb a roost during hot days
- If you find an abandoned or stressed flying-fox on the ground, do not handle them. Please call 1300 ANIMAL (264 625) so a trained and vaccinated carer can rescue
Kuluin Options Paper
When managing flying-fox roosts, there are a number of techniques in the toolbox, but there is no one-size fits all option. There are some early intervention options that can reduce impacts on residents whilst balancing the views of many residents preferring nothing be done to the vegetation or enjoy having flying-foxes close to them.
At high-conflict sites, these competing ideals can unfortunately become quite divisive within a community. More severe on-ground actions must be weighed against the legislation, welfare of the species and the potential impact on the broader community and region before they are implemented. Therefore, when high-conflict sites are established, we engage an independent consultant. They will look through all the possible actions within the Regional Flying Fox Management Plan and recommend a plan to balance all the issues discussed above.
This process has recently been completed for three roost sites at Kuluin. The three sites are all within 500 m of each other and have been occupied for varying amounts of time. It is logical that these three sites are linked and that actions at one site would influence the outcomes at the others.
To find out more about the next steps at the Kuluin sites, check out the Management Options Paper.