Annual report: 2011 compared to 2010

While analysing the results of this project over the full 5 years I found that the analysis was hampered by the differing numbers of observers in the various periods.   Was a difference due to a real change in the birds' behaviour or simply an artefact of observer 'X' not being active at a point in time?  An earlier post discusses the issues of observer effort.  To overcome this problem I have decided to compile this post contrasting 2011 with 2010 where the level of observer effort was broadly similar.

Of the  167 species recorded in this project 157 species were reported in one or both of the years covered by this analysis.  Of these 157 species:

• 16 were reported in 2010 but not in 2011;
• 11 were reported in 2011 but not in 2010; and 
• 130 species were reported in both years.

Looking at the entire 157 species there is a very strong correlation (correlation coefficient 0.9006) between the number of months each species was reported in the two years.  Thus it can be concluded that the two data sets are reasonably consistent.

Of the species recorded in 2010 but not 2011, 15 were sighted in a single month while Red-capped Robin was seen in 2 months.  The species seen in 2011 but not 2011 include (of course) 5 species recorded for the first time in this project.  3 other species were seen once in 2011 after absence in 2010 while:

• Painted Button-quail were seen in 3 months (flushed from cover while walking our dog);
• Hardhead seen in 4 months; and
• Black-shouldered kite seen in 6 months.

The latter two observations show a return to more normal rates than 2010.

33 species were reported every month in both years.

The following table shows the aggregate number of months in which members of the broad groups of species were seen in the two years.

Category	2010	2011
1 Waterbirds	121	146
2 Birds of Prey	62	72
3 Parrots and Relatives	88	89
4 Kingfishers and other non-songbirds	125	131
5 Honeyeaters	97	90
6 Flycatchers and similar species	122	128
7 Thornbills, Finches and similar species	192	198
8 Other, smaller birds	109	114
9 Other, larger birds	95	94

The broad similarity of the results is clear, with the exception of:

• Waterbirds, reflecting the movement of many species in this group to the inland swamps in the wet of 2010 and their return in 2011; and
• Birds of Prey, reflecting the amount of 'action' on the Hoskinstown Plain in late 2011 due to the large amount of prey (such as mice).

The picture for the Honeyeater group is interesting since that is the only group in which 2010 exceeds 2011.  Of the 11 species in the group,

• 5 have the same (high) score in both years,
• Noisy Friarbird and (the relatively uncommon) White-plumed Honeyeater show 2011>2010; and
• the remaining 4 species (New Holland, Yellow-faced, White-plumed and Brown-headed Honeyeaters) show a higher reporting rate in 2010 than 2011.  The value for New Holland was unusually high in 2010 and I was surprised to see that none of us reported Yellow-faced in 2 months in 2011.

Links to other parts of the Annual Report
Overview, 2010 cf other 4 years; Breeding