Sambar Browse Plants - Boom and Bust?

Previously, authors such as Arthur Bentley, Max Downes and I have commented on the fact that fire, logging and other disturbances in the forests have a positive influence on sambar breeding success and deer numbers. Bentley based his comments on his experiences before and after the 1939 fires, Downes on his extensive experience with wildlife populations both here and overseas, while in my case the boom in sambar numbers after the major bushfires of the past 15 years convinced me of this reality.

By rights, with every wildfire-driven boom in deer numbers there ought to be a bust, as the forest recovers and feed availability and quality declines. That is of course, unless hunting, predation, disease, parasites and accidents or a combination of these factors intervene to avert the bust (or a major wildfire kills a lot of deer and re-sets the vegetation clock to avert this happening).

In Victoria, it seems likely that only hunting significantly reduces sambar numbers – all of the rest of the constraints on deer numbers are probably largely irrelevant with little or no impact. But what happens when hunting or culling by landowners is non-existent or insufficient, does this result in a bust?

A dry winter and spring in East Gippsland in 2017 combined with an ongoing decline in feed resources in the bush since the major fires got me thinking about that possibility. This was reinforced when talking with couple of experienced Gippsland hunters who had recently come across animals that were in poor condition.

A trip into a local river valley in mid-October (when the boom in spring growth would normally be well underway) indicated that the country was bone-dry and feed was indeed low in the area – and heavily browsed and grazed by both native wildlife and the deer.

This valley can be legally hunted and is regularly targeted by road-running spotlighters, but despite the lack of feed a couple of deer that were seen seemed to be in reasonable condition. There was no immediate cause for concern there, but maybe the next few months without fresh growth will tell a different story?

But what happens when there is no legal access for hunting and isolation makes illegal hunting and culling by landowners unlikely? Much of far-eastern Gippsland is national park where hunting is not allowed and the surrounding forests and farming areas are isolated. In this situation will sambar numbers boom and inevitably bust following the recent major fires to the real detriment of the native vegetation? American biologist and author Aldo Leopold’s comment many years ago that a mountain lives in fear of its deer may not be too far from the mark if sambar are ever allowed to boom and then bust without any management intervention by hunters.