Many hunters would have been bemused by pre-season waterfowl count data that recorded a lot of water and a significant breeding event but didn’t locate large flocks of game birds.
So where were the ducks?
It is a critical question and the lack of a scientific answer points to the need for more research so game management decisions can be based on facts and data.
In its submission on the 2017 duck season, Field & Game Australia again raised the need for new scientific models, specifically designed for the purpose of monitoring and managing the nomadic and dynamic wild duck populations in Australia.
Alice Bauer, an honours student at the University of New England, has just completed a paper that used Field & Game Australia’s annual November waterfowl counts from 2001–2014 and the available scientific literature to look at factors affecting abundance in Victoria.
The period takes in the millennium drought, of which the driest years were from 2002–2006.
The paper says this about dry periods:
“Some species are capable of flying huge distances of up to 3200 km in one week to arrive at favorable habitat (Roshier et al. 2006). Whereas during periods of drought, waterfowl will congregate in numbers of up to 50 000 at wetlands of drought refuge (White 1987; Maher & Braihwaite 1992).”
Alice says the wetlands important to ducks during drought are known, but there is a lack of knowledge on where waterfowl go during periods of above-average rainfall.
“Thus, the overarching aim of this study was to investigate where waterfowl go when conditions are wetter than average, and what wetlands are important during these times.”
The study used counts of shelduck, hardhead, wood duck, pacific black duck, pink-eared duck, chestnut and grey teal and shoveler, all game species and the protected Freckled duck, which is also recorded in FGA counts.
The paper notes significant scientific work (Roshier et al. 2001; Roshier et al. 2006; McEvoy 2015) that has advanced knowledge of the most nomadic duck species and their dependence on inland water.
Analysis of banding returns of grey teal show that some individuals can move, on average, 180 km per day and cover up to 3200 km in a few weeks (Frith 1976). Grey teal have been recorded to take overnight movements of hundreds of kilometres to intercept flood waters flowing down dry inland rivers or long distance movements to isolated wetlands in an otherwise hostile landscape (Roshier et al. 2006).
The paper concludes that the movement ecology of waterfowl poses many unanswered questions and while several theories exist, the actual outcome as to where the ducks go and where they come from has gone unanswered for about 50 years.
Gaps in the Eastern Australia Aerial Waterbird Survey, the Victorian Summer Waterbird Count and FGA’s own counts (wetlands counted are not standardised) are noted in the paper.
The conclusion is that more research is required to build knowledge of where waterfowl go when conditions are wetter than normal, and what wetlands are of importance to the waterfowl once they get there.
“From the results of this project and the work of others we know that during periods of drought, waterfowl concentrate on sites of refuge in Victoria, and following the conclusion of long drought, waterfowl disperse on a mass scale from Victoria.
“To where these waterfowl disperse is not known. Theories suggest nomadic species disperse to flooded inland rivers. If so, do they return again when resources dry? It is also suggested that locally breeding species disperse to newly inundated wetlands. What wetlands are these? And again where do they disperse to? And finally, the qualities that make a wetland significant for waterfowl during periods of ‘wetter than average’ conditions is a topic open to investigation.”
“Some species are capable of flying huge distances of up to 3200 km in one week to arrive at favorable habitat (Roshier et al. 2006).