Annual report: 2013 compared to 2012

I have indicated in the overview that the number of observers was a tad unstable in 2013.  Despite that I think some nuggets of information can be picked out by comparing the two years.

Of the  183 species recorded in this project 164 species (89.6%) were reported in one or both of the years covered by this analysis.  Of these 162 species:

• 11 were reported in 2012 but not in 2013;
• 14 were reported in 2013 but not in 2012 (of which 7 were reported for the first time in 2012); and 
• 139 species were reported in both years.

Looking at the entire 164 species there is a very strong correlation (correlation coefficient 0.88) 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 11 species recorded in 2012 but not 2013, 7 were sighted in a single month 1 was seen in 2 months; 2 in 3 months and 1 (Latham's Snipe) in 4 months. 

For those seen in 2013 but not reported in 2012:

• 10 species (6 of these being additions to the area list) were seen in a single month
• 2 species (no additions) were seen in 2 months in 2012;
• 2 species (1 addition) were seen in 3 months in 2012;  and 

 38 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.

The similarity of results between the two is readily apparent except for Birds of Prey,  Honeyeaters, Thornbills and Other Smaller birds.

With respect to Raptors (ie diurnal Birds of Prey) the differences are +/- one month for most species, but with significant differences (both drops) for Spotted Harrier and Collared Sparrowhawk.  I believe both of these reflect the unavailability of particular observers.

For the Honeyeater group 6 of the 12 species recorded are covered in 10 or more month of the year.  There are 4 other species with differences of +/- 1 species months.  The big drops are: 

• Yellow-tufted Honeyeater (from 3 -> 0, probably reflecting my not having been to the specific part of Yanununbeyan SCA this year); and 
• White-naped Honeyeater (from 7 -> 1.  I have no idea why this might be so, as the species still seems common in the forest of the Brindabellas and Tallaganda.)

A similar situation applies with the Thornbills and allies group.  Considering the observer changes the records showing that 15 of 20 species in the group were reported in 11 or 12 months of both years is remarkably consistent.  The major changers are both relatively uncommon species:

• Speckled Warbler dropped from 5 to 3; and 
• Southern Whiteface from 9 to 6.

I am inclined to regard this as an outcome of generally reduced observer effort, including by this author!

The major increase group is the "Other Smaller birds".  The overall reporting rates are lower for this group (which includes a number of migrant species) but in general for the 21 species in the group the rates are similar for the two years.  The four species with the greatest increase are Eurasian Slylark, Golden-headed Cisticola, Rufous Songlark and Brown Songlark.  I could offer an hypothesis that these increased reporting rates are a byproduct of the greater attention paid to the Hoskinstown Plain when checking out the swamp in the Summer of 2012-13.

Links to other parts of the Annual Report

Overall picture

Breeding Birds

2013 cf previous 6 years