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

Annual report: 2012 compared to 5 previous years

The following table summarises the number of species reported by month and year.

	2007	2008	2009	2010	2011	2012
jan		69	86	89	95	94
feb	59	74	71	88	89	96
mar	69	72	78	79	88	95
apr		65	71	79	75	93
may	61	65	82	80	80	80
jun	51	69	71	77	65	79
jul	54	58	66	77	78	87
aug	57	72	74	80	90	97
sep	67	79	86	86	101	98
oct	67	85	92	97	99	113
nov	73	84	106	96	108	106
dec	60	84	96	95	99	116

Looking at the 150 species which were recorded in the area in 2012 in comparison with  the previous 5 years a first comment is that 11 species were observed in this area for the first time in 2012.  These were

• Australian Pelican; Australian Spotted Crake; Banded Lapwing;Chestnut-rumped Heathwren; Golden-headed Cisticola; Great Egret; Hoary-headed Grebe; Intermediate Egret; Restless Flycatcher; Swamp Harrier; Wonga Pigeon.  

I will have already commented on some of these in the linked posts.  Most of the other species in the list are regularly seen in the COG Area Of Interest but - for unknown reasons -  have been a little reluctant to reveal themselves here.

Of the 155 species for which comparison is possible, 19 have been recorded in every month throughout the 6 years (obviously including every month of 2012) These are:

• Australian Wood Duck; Galah; Sulphur-crested cockatoo; Crimson Rosella; Eastern Rosella; Laughing Kookaburra; White-eared Honeyeater; Noisy Miner; Willie wagtail; Magpie-lark; Welcome swallow; Yellow-rumped thornbill; White-throated treecreeper; Common starling; Grey butcherbird; Australian Magpie; Pied Currawong; Australian Raven; Little Raven.

For the 118 species recorded in 2012 which changed the proportion of months in which they were  recorded 98 (83.1%) showed an increase in the number of months in which they were recorded and 20 (16.9%) showed a decrease.  I shall return to an analysis of those numbers below, but a reconciliation tree diagram may be useful:

The 27 species recorded in the prior 4 years which did not appear in 2012 were:  

• Emu: Chestnut Teal; Spotted Dove; Fork-tailed swift; White-bellied Sea-eagle; Whistling Kite; Grey Goshawk; Silver Gull; Glossy Black-Cockatoo; Little Corella; Scaly-breasted Lorikeet; Fuscous honeyeater; Scarlet Honeyeater; Crescent Honeyeater; Spotted quail-thrush; Rufous Fantail; Satin Flycatcher; Jacky Winter; Red-capped Robin; Horsfields Bushlark; Zebra Finch.

Most of these birds are not common in the Canberra region.  The possible exceptions are:

• Silver Gull (but only really common along Lake Burley Griffin: a habitat not present in this area); and
• Little Corella (a recent arrival in Canberra which does not yet seem to have spread to out of the urban area).

It is pleasing to note the inclusion of Spotted Dove in the list of "not reported species".  As the species is being reported increasingly frequently in the urban area of Canberra I fear it is only a matter of time before we get a serious invasion.  If anyone spots one of these pests, please let me know asap.

Increasing species

There are 30 species recorded every month in 2012 which have been omitted at least once in earlier months.   With a 6 year series of observations I regard the 13 species only omitted once or twice as observer error (in most cases the missing period is early in the life of the project whenI was the only observer!).   Most of the 17 other species in this group of 30 are cases where the increased number of observers in recent years has added to the completeness of reports.  This is particularly the case for Eurasian Coot now seen every month at one or more sites with suitable water.  A second species with an obvious explanation is Tawny Frogmouth, now reported every month from Whiskers Creek Rd since I am specifically searching on a daily basis for a resident family, while in the past observing these birds was serendipity.

At the other end of the spectrum 14 species were recorded in a single month in 2011 and  tend to appear in the list of 'increasers' as a statistical quirk since 1/12 > 1/46!  They are clearly unusual in the area and will not be considered further.

A group seen in  at least 6 months in 2011 for which an increase of at least 10% has been noted amounts to 47 species.  I can't offer a comment about all of these so what follows is 'picking the eyes out' of the list.

• Many raptor species are in this group.  Possibly the most spectacular increase is the Spotted Harrier  which is far from common in the COG area but after an initial sighting late in 2011 has been reported from the Hoskinstown Plain in 10 months.  A Black Falcon was first seen in 2011 and was reported in early 2012 and again in December.  Specific blogposts have been written about the influxes of Black-shouldered Kites; Brown Falcons; and Barn Owls. in 2011: the birds continued to be more evident through 2012, although Barn Owls were absent in the latter months.  (Presumably mouse numbers have declined with the drier weather.)
• A number of birds which include water in their habitat preferences are also included. The large White-faced Heron was an occasional visitor to the area in the past and a sighting of 4 birds together in 2009 was sufficiently unusual to get a mention in the COG Annual Bird Report.  This year up to 15 have been seen together on a Hoskinstown swamp.   That site is also responsible, in part at east for increased reporting of Southern Shoveller, Hardhead, Black Swan and Eurasian Coot.
• Eastern Yellow Robin is usually thought of as a bird of the damp gullies.  The wet conditions of late 2010 and early 2011 led to a pair taking up residence at Whiskers Creek Rd.  They disappeared in early 2012 but reappeared in Spring of that year.
• The group of birds which are adapted to grasslands have all been reported more frequently as a result of extra observer effort on the Plain.  This includes:
• Finches (Red-browed Double-barred and European Goldfinch and Diamond Firetail); 
• Skylark; 
• Australasian Pipit; and 
• Red-rumped Parrot

Decreasing Species

Only 6 species show a decline of >10%.  5 of these are migrants and an increase of 1 month of observations in 2012 would have moved these out of this group.  The most significant decrease is of Rock Dove: either 

• someone has had pigeon pie; 
• the local Peregrine Falcons and Brown Goshawks have been more active. or
• someone has recently started shutting the door on their loft!

Links to other sections.

Overview report, 2012 cf 2011, Breeding