Parrot population data and a question for birding aus members

I use E-bird a good deal like many I suspect. I have noticed a pattern in
parrot data. I looked at aproximately 30 species of parrots in NSW, VIC,
NT and noticed that there are more recordings/sightings for most species in
April/May as opposed to Sept/Oct.

I have my own ideas as to why this is so but would love some input from
local Aussies.

Thanks very much!

Don Kimball