Wednesday, February 23, 2011

Initial GBBC reaction

I looked through the Great Backyard Bird Count data for a while today to see if any interesting sightings had been reported, as well as to examine some of the population levels observed. At the time of this writing 102,063 birds have been reported from 133 species on 1,402 lists. This is down on all counts from last year's 153,705 birds of 141 species on 1,994 lists. While 2011 numbers will increase a bit more, it seems certain the persistent snow cover, Saturday's extreme winds, and a light snowfall Monday morning definitely seemed to keep people indoors and a few more birds in hiding apart from possible losses this winter.

I went into this examination thinking that many species, especially those that persist year-round or do not move during the winter, would be reduced in number because of the historic snow depth and snowfall rate during January. Comparing the number of individuals can be somewhat silly when you do not have the same number of checklists submitted as of course there are fewer birds! One way to combat this is to take all of the totals and divide each species by the number of checklists submitted that included that species. For example, 15,467 Canada Geese were seen on 231 checklists last year, while 6,585 were seen on 167 checklists this year. That is 66.96 per list in 2010 and 39.43 per list in 2011. Fewer Canada Geese and less per sighting makes perfect sense to me as they are prone to feeding on open lawns, of which there are less than usual right now.

Carolina Wren is always a good species to test the severity of the winter. So far in 2011, 370 were reported from 267 lists, a number which will increase some still. This is much less than the 631 on 421 lists from 2010. A species like Gray Catbird - easily identified and more often overwintering in Connecticut - also provides an interesting look into the season. 2010 had 37 on 27 lists while 2011 had only 9 on 7 lists. Here are some more intriguing things I noted:
  • The entire warbler total was 4 Yellow-rumps from one list in Madison, very likely Hammo; 2010 had 93 on 17 lists and one each of Yellow-breasted Chat and Orange-crowned Warbler (actually, I found that bird at Frash Pond in Stratford, and a very satisfying find it was)
  • There were a couple thousand more Common Grackles this year, but over a thousand less Red-winged Blackbirds, despite their appearance on more checklists
  • Nearly all of the common "feeder" birds had lower totals and averaged less in average number on checklist per species, from woodpeckers to nuthatches to the sparrows, representing a drop from the tough winter
  • Common Redpolls started moving this weekend, ironically enough, with hundreds seen compared to only one in 2010
  • Not one Ruby-crowned Kinglet was seen and only 11 Golden-crowned were spotted
  • Herring and Ring-billed numbers were down dramatically just ahead of their expected date of movement, but in an odd way; Herring Gulls were seen on more checklists despite their total being less than half of 2010's 7,971
  • Owl numbers can move around a bit due to detection (or lack thereof), but Eastern Screech-Owl dropping to 7 birds on 6 lists this year from 35 on 18 in 2010 is quite a big fall
  • Some shorebirds took a tumble, too, as not one Black-bellied Plover was seen, fewer Sanderling and Dunlin were noted, and Ruddy Turnstones went from 179 last year to 11 this year
  • Not a single Northern Goshawk was found, and while raptors numbers were lower overall, we will need to calculate them as a percentage of total checklists to get the best idea as they are typically found one or two birds at a time
  • American Robin numbers were down by about a third in all regards but...
  • ...Cedar Waxwings tripled in number and were on a few more lists than last year as well
  • Eight species seen this year but not last included Eurasian Wigeon (Stratford Point and Bridgeport), Redhead, American Bittern, Black-headed Gull, Eastern Phoebe, Lapland Longspur, Dickcissel, and Evening Grosbeak
  • There were fifteen species seen last year but not on this GBBC - Harlequin Duck, Black Scoter, Pied-billed Grebe, Eared Grebe, Northern Goshawk, Golden Eagle, Black-bellied Plover, Willet, Glaucous Gull, Red-headed Woodpecker, Ruby-crowned Kinglet, Brown Thrasher, American Pipit, Orange-crowned Warbler, and Yellow-breasted Chat
This may change some as late checklists are entered, and I will post more on it sometime soon. All of this basic analysis of public information shows how important data-based conservation efforts are, from using eBird as much as possible to participating in counts like this one.

1 comment:

  1. I'm afraid I didn't participate in the bird count, but I did have a northern goshawk in my back yard in Waterford a few weeks ago.