Sunday January 15 (Day 35) both adults at nest; interesting behavior

[NewMexiKen]

Today is day 35 of incubation, if our ground observations are correct, this is the expected hatch day for the first egg. We arrived at the eagle nest around 10:25 AM and observed for about 1/2 hour. We immediately saw one adult sitting on the left (east) rim of the nest, sometimes looking down into the nest. No other eagle appeared to be on the nest. It was a chilly 53 degrees (F) and there was a stiff gusty breeze out of the NNW which caused the Melaleucas in front of the nest, as well as the nest tree twigs to sway considerably, often obscuring the nest. However, when the "harmonics" were just right I sometimes got a full view of the nest. Initially my 12 or more photos showed only the one adult.

10:28 AM


I left the nest momentarily to check out the roost trees to the west, and as I was returning, Mary Lou called out that another eagle had flown in from the rear (south) of the nest. When I got to the nest I could see only one eagle...

10:31 AM


...but then, after several minutes, the head of a second appeared above the nest rim.

10:32 AM


10:39 AM


No prey items were visible, and at no time did they appear to be eating or tearing at prey. After a few minutes, one of the eagles (the first one?) flew out the near (north) side of the nest and flew low to the left (east), disappearing behind the trees on the highway median.

10:41 AM


After this we got views of the top of the head of the second eagle deep in the nest.

10:53 AM


We do not know how to interpret what we saw. Mary Lou believes there was an exchange of incubation or brooding duties. The pattern of the junction of the white head feathers and the brown body of the standing bird look quite identical to me-- did the next arrival immediately start incubating duties?

Since the incubating bird was very low in the nest, this suggests that the first egg had not hatched, but it was chilly and this may have been expected in any event.The first adult's behavior of looking down into the nest has been associated with the hatching of the first egg in past seasons. I could not guess the sex of either adult. The bird in flight looks rather stocky and also lacks the streaking of the outer tail feathers that we saw early in the season on the male.

We also saw this Buteo gliding over the nest.



At first I thought it was a Red-shouldered Hawk, because of the contrast between the dark wing tips and the proximal light area. When I saw the photo I recognized that the white area consists of a group of new primary feathers, not the light base of the primaries at the tip of the wing as in Red-shouldered. This bird has a dark belly band and dark patagial marks and lacks red on its tail, characteristic of an immature Eastern Red-tailed hawk.