This year, the number of robins persisting through the winter in the foothills has become a topic non-birders of my acquaitnance are commenting on. I too suspect the juniper berry crop is higher this year due to summer moisture, and the Robins and Townsend's Solitaires may be competing for this resource.
I regularly walk my local patch and have observed robins throughout the fall and winter. The numbers have not been as high as you have observed but they are a continuous presence regardless of how cold it gets. I have heard and seen a couple of Townsend's Solitaires, but the robins have been far more consistent and abundant. Makes me wonder whether a combination of food supply and milder winter temps triggers this behavior. According to the species account for American Robin on Birds of North America: "Restless migrant and wintering flocks are seen in many new areas within the geographic range of the breeding population, where there is either damp soil or a source of berries. Wintering numbers may vary significantly from year to year in many (especially northern) areas." Suggests we may be seeing irruptive-like behavior. Definitely worth folks' time to note Robin #s and submit observations to eBird! Ed Furlong Evergreen, CO On Jan 12, 9:53 am, Hugh Kingery <ouze...@aol.com> wrote: > Thismorning I counted 325 robins flying acrossour driveway. Maybe > more. Maybe fewer. (Theway they swirl around you have to have eyes in the > back of your head to countaccurately.) Urling and I marvel at their chorus > that emanates from the oaksand conifers at and near our house. They chatter, > tweet, sing, squeal, andsquawk incessantly, particularly in the morning and > mid-afternoon. Flocks flyout and blanket the trees; they announce their > presence constantly. > What theyfind for food puzzles me – this morning some dined on > juniper berries/cones –and that makes me wonder how the Townsend’s Solitaires > can persist. The drovesof robins browbeat the solitaires by sheer numbers. > Yet the invaders spend timein the scrub oak and the riparian stream bottoms > and on the ground. They don’tpatronize our feeders (suet, seeds, e.g.). Our > complement of solitaires droppedfrom six in November to three this month. > Adding tothis: the Denver Christmas bird count had its > second-highest count of robins –1828, Joey Kellner says. Denver Urban count > had about 1400 – 75% more than ever(previous high, 794; 24-year average, > 285). We can’t really tell how many populate our little vale: before I’d > nevercounted more than 150. More flocks persist in Castlewood State Park, > ahalf-mile away. The total must number thousands. > This immensegaggle of robins, I think, amounts to the biggest > bird story this winter, atleast in Denver metro (bigger than a rare owl, > wayward warbler, or vagrant sparrow). > > I wonderhow many robins Cobirders, collectively, saw this morning > – do we have any wayof amassing this information? I suppose eBird could help, > but it doesn’t have reportsfrom many observers (and mine won’t go in until > next month). > > Hugh Kingery > Franktown, CO -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to cobirds@googlegroups.com. To unsubscribe from this group, send email to cobirds+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/cobirds?hl=en.
