Lake John (Jackson Co) Red-necked Grebe mystery

[Charles Hundertmark]

From Wednesday through yesterday morning, Paul Slingsby and I went to North Park for an RMBO ColonyWatch monitoring trip. On each of those days, we made a stop at Lake John to track the progress of the Red-necked Grebe nest. We hoped to find young or perhaps, catch the hatching of eggs. Instead, we found a mystery.

On Wednesday, accompanied by YCC volunteer Katie Crain from Arapahoe NWR, we observed the nest for an hour and a half. Both adults were on or near the nest off and on during the observation. At one point when both adults were off the nest, there appeared to be eggs still on the nest. At 5:18 when we left the lake, the female was on the nest and the male was near.

On Thursday, along with Nicole Hornslein from the refuge, we briefly checked the pair in the fog. The male was on the nest and the female entered the cove before we left.

Friday evening, a day and a half after our previous visit, we observed for a little over an hour and a half until well after sunset. The male was on the nest for just over an hour. After leaving the nest, he attacked a local coot. Eventually, he left the cove for the open water of the lake where he remained until we left. The female was not seen the entire time. The nest appeared empty.

Saturday morning, we were joined by Lee and Linda Farrell. We first spotted what we thought was the male on the open water of the lake away from the nest area. Shortly thereafter, the female was spotted some distance away from the male. We saw no sign of young near or on the backs of either adult. A half hour into our observation, we saw a second male appear near the female. All three birds were in adult breeding plumage. The pair swam into the cove near the nest, and at one point one carried weeds toward the nest. Shortly after, they left the cove and remained in the open water during the remainder of our observation. 

The nest was empty, with no sign of eggs or egg shells and many small black winged wasplike insects, about flying ant size, were swarming over the nest surface. Speculations are plentiful, but we have no idea what is going on now. 

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Chuck Hundertmark

2546 Lake Meadow Drive

Lafayette, CO 80026

303-604-0531

Cell: 720-771-8659

chunde...@gmail.com

[Cheri Phillips]

My guess would be a raccoon ate the eggs.

Cheri Phillips
Centennial, CO