Annual report: 2012 compared to 2011

While analysing the results of this project over the full 6 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 2012 with 2011 where the level of observer effort was broadly similar.

Of the  177 species recorded in this project 162 species were reported in one or both of the years covered by this analysis.  Of these 162 species:

• 12 were reported in 2011 but not in 2012;
• 20 were reported in 2012 but not in 2011 (of which 11 were reported for the first time in 2012); and 
• 130 species were reported in both years.

Looking at the entire 162 species there is a very strong correlation (correlation coefficient 0.878) 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 2011 but not 2012, 9 were sighted in a single month and 3 were   seen in 2 months. 

For those seen in 2012 but not reported in 2011:

•  8 species (5 of these being additions to the area list) were seen in a single month
• 3 species (all additions) were seen in 2 months in 2012;
• 4 species (1 addition) were seen in 3 months in 2012;  and 
• 5 species (2 additions - surely reflecting a change in observer behaviour?) were seen in 4 months.

In the final category special mention could be made of the White-winged Triller,  which was reasonably common in this area and the urban area of Canberra prior to 2010-11 but reported very sparsely in that year but now seems to have re-established itself.

 36 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	2011	2012	difference
1  Waterbirds	146	200	54
2 Birds of Prey	72	101	29
3 Parrots and Relatives	89	91	2
4 Kingfishers and other non-songbirds	131	124	-7
5 Honeyeaters	90	101	11
6 Flycatchers and similar species	128	126	-2
7 Thornbills, Finches and smiilar species	198	202	4
8 Other, smaller birds	114	116	2
9 Other, larger birds	94	91	-3
Total	1062	1152

The similarity of results between the two is readily apparent except for Waterbirds, Birds of Prey and to a lesser extent Honeyeaters .

The situation for Waterbirds is summarised in the following chart.  I realise it is cheating to include 2010 in a post titled "2012 compared to 2011" but 

• it is my post; and
• I prefer to explain the situation rather than

• leave it obscure; or
• change the title and do a lot of work to include 3 years in everything!

It appears that the number of species reported per month is quite stable from January 2010 until June 2011 (which covers the very wet period of 2010 with many waterbirds absent, breeding in the revitalised the inland) when the number kicks up - presumably as the Inland begins to dry out.  Another period of stability follows until mid 2012 by which time a dry period has resumed and the waterbirds have discovered the swamp on the Plain.

With respect to Raptors (ie diurnal Birds of Prey) the position is summarised in this table of months reported x year x species:

species	2010	2011	2012
Australian Hobby	2	5	3
Black Falcon		1	5
Black-shouldered kite		6	11
Brown Falcon	9	11	12
Brown Goshawk	9	7	11
Collared Sparrowhawk	4	3	6
Little eagle	6	9	9
Nankeen kestrel	12	12	12
Peregrine falcon	5	4	8
Spotted Harrier	1	1	10
Swamp Harrier			2
Wedge-tailed Eagle	12	12	12
Whistling Kite	1	1
White-bellied Sea-eagle	1

Of the 14 species covered by the table, 2 were not reported in 2012 and 1 (Swamp Harrier - finally) was added.  5 species - highlit in yellow- are regular residents throughout the period.   Peregrine Falcon is a localised resident and Black-shouldered Kite and Spotted Harrier have become regular in the past year: the former returning after having moved out of the area during the drought and the latter possibly reflecting greater effort on the Plain.  The impact of these last two species largely explain the increased reporting for this group.

The other "large mover" is the Honeyeater group becomes easier to understand at the species level.  6 species (Brown-headed honeyeater,Eastern spinebill, Noisy Miner, Red Wattlebird; White-eared Honeyeater and Yellow-faced honeyeater) are reported nearly every month in all years.  Scarlet and Crescent Honeyeaters have not been reported since a single sighting of each in 2010.  A few other species do the migrant 'thing' consistently each year.  This leaves relatively high 2012 rates for Yellow-tufted Honeyeater (in Yanununbeyan SCA) and New Holland Honeyeater (mainly a site in Widgiewa Rd) as explaining the increase since 2011.

Links to other parts of the Annual Report

Overview; 2012 cf other 5 years, Breeding