Thursday, September 16, 2010

Rocky Mountain Arsenal, Aurora Reservoir & Banner Lakes

September 15, 2010

Richard Stevens:

Before sunrise (6:00 am is opening time) Jacob Washburn, Amy Davenport and I listened for owls at Rocky Mountain Arsenal; unfortunately none came out this morning.

We then made the 6 mile loop around Lake Ladora, detouring to the Rod & Gun Club Bird Blind and Havana Ponds. Birds other than sparrows were scarce today (winds were quite strong which did not help).

A Plumbeous Vireo was in the trees over the R&G Club bird blind. Sparrows included: Chipping, Vesper, Lark, Lincoln's, Brewers, White-crowned and Song. A Marsh Wren was heard in the cattails at the southeast corner of Ladora.

Two Warbling Vireos one of which was quite yellow were found in the tree line below the Lower Derby Lake dam. Their lores were white not black as in a Philadelphia Vireo. As has been discussed recently on the Colorado listserves, the vireos can show much yellow in fall.

Yesterday afternoon, Rebecca Kosten and I joined Bill and Angel Cryder for a bike ride around Aurora Reservoir (Arapahoe County). We entered the park from the south side, near mile marker 1.0 (be sure to check the hours the park is open if entering such, they will lock the gates on you if you miss the closing time and it's a long trip back around as I found out one day).

Several dozen Double-crested Cormorants and 19 Pied-billed Grebes were in the cove with the rookery.

There were no gulls at their usual spot off the point at mile marker 2.0. A lone Common Loon was swimming in the cove at mm 3.0. There definitely were fewer birds on the water than our last visit.

When we arrived at the swim beach (7.8 miles later), we scoped 350+ gulls only to find California and Ring-billed Gulls.

We noticed at the point off mm 1.0, many gulls, one of which was quite dark. We scoped the dark one to find an adult alternate plumage Lesser Black-backed Gull. Perhaps the one that has been summering between Cherry Creek Reservoir and here? After about 15 minutes, the Lesser Black-backed Gull took off and disappeared to the west. We hoped someone would report it at Cherry Creek Reservoir (about 9 miles west).

We rode back to mm 1.5 and then walked the 250 yards to the point. Another 300+ California and Ring-billed Gulls were found.

Rebecca and I said goodbye to Bill and Angel and headed to Banner Lakes Wildlife Area. Although winds were measured at 14+ mph, it was too nice a day to go home.

At Banner Lakes, we walked down to pond 10 and back. Best birds were 2 Townsend's Warblers in the windbreak west of pond 7. A Plumbeous Vireo was in the windbreak west of pond 8. We had to stay quite long to get enough looks to make sure it was only a Plumbeous Vireo.

We scoped the area after sunset, no owls were found this evening.

No comments: