Driving through Wilsons Prom as the sun rises, I can’t help but feel incredibly lucky. Although dragging myself out of a warm cosy bed at 5am required considerable effort, it wasn’t for the spectacular sunrise. My true motivation is the knowledge that there are plump little mice waiting for me.
I’m headed to check my traps and see how the New Holland mice on Yanakie Isthmus are faring this month. Arriving at the sites just on sunrise, I walk along the traplines, clambering through the vegetation looking to see which traps have closed doors – indicating an occupant.
Peering into a trap, I pull out the warm fluff to see who has been lured in overnight by the scent of peanut butter, golden syrup, vanilla essence and oats.
Discovering a New Holland mouse, I tip it into a bag and get to work weighing it, taking a genetic sample, and checking its gender, age, and reproductive status before releasing him and re-setting the trap.
Unconvinced that I’m actually a giant, terrifying predator, the New Holland mouse chooses to explore my lap before heading home to his burrow to sleep until nightfall. I quickly move on to the next trap, not wanting to keep the mice waiting any longer than necessary.
It’s breeding season for New Holland mice at the moment, and the next individual I encounter is playing her part well. Adult New Holland mice usually weigh about 18-20 grams at these sites. This little lady is a hefty 32g, soon to give birth to up to six babies. She will breastfeed them for the next month, until they’re ready to head out and find tasty seeds, leaves, invertebrates, and fungi to eat.
As the New Holland mouse breeding season can last 5-7 months, some of her kids from this litter will mature and have offspring of their own in the next few months. During that time, she will produce a few more litters herself.
Despite what may seem like quite high reproductive potential, New Holland mice are threatened and populations can disappear quickly. Breeding season length and success are highly dependent on resource availability – if there isn’t much food to go around, there will be fewer, smaller litters, with fewer of those offspring surviving to maturity.
Figuring out the specific factors driving population success will help us to protect and conserve the few populations of New Holland mice that remain in Victoria. A challenge definitely worthy of a 5am start.