The pair that nested on Chevy Chase Lake Drive a couple of years ago were in a tree that was almost devoid of leaves - it was well on its way to dead. They were on one of the lowest branches, really quite exposed. We know the young hatched and they certainly grew to a size where I assume they fledged. That pair returned one additional year but aren't there this year.

In terms of predation, cover doesn't help when it comes to snakes or raccoons. I think the bigger concern is disturbance and nest abandonment. 

Why a supposedly enlightened county like MoCo, supposedly so concerned about the environment and conservation, has to allow tree-trimming during nesting season, is a mystery. Though there are lots of trees that need trimming and they have only so much time to do it. 

If they haven't already trimmed the tree, and there isn't any immediate chance of a limb breaking off (or if it does break, harming someone) you might want to call the County arborist ASAP. Her name is Laura Miller and she's actually the  Forest Conservation Coordinator  	240.777.7704

or e-mail her at 

But as to cover, see the write-up from the Birds of North America, below. 

Ellen Paul
Chevy Chase MD


Site Characteristics.

Nest height varies according to available substrate. Average nest heights in forested locations include: 15.2 m ± 3.7 (SD) for coastal Virginia (n = 65; Watts 1989), 18.3 m ± 0.6 (SE) for se. Missouri (n = 33; Laubhan and Reid 1991), 15.2 m ± 0.33 (SE) for Tuscaloosa, AL (n = 17; Wischusen 1979), 2.3 m for Spring Creek, AL (n = 17; Drennen et al. 1982), 13.1 m for Kentucky (n = 13; Mengel 1965), and 9.4 m for Indiana (n = 17; Mumford and Keller 1984). In large trees, nests are usually placed away from trunk on outermost fork of supporting limb (Criswell 1951, Laubhan and Reid 1991, BDW). In situations with closed canopies, nests are typically placed on lowest horizontal limb (Bent 1926, Watts 1988) and often hang over water (Golsan and Holt 1914, Drennen et al. 1982). In upland areas, vegetation density under nests is generally low (Watts 1989, Laubhan and Reid 1991), with a parklike appearance. Pairs nesting on islands or along estuaries nest in available shrubs with nest height reflecting vegetation height (McVaugh 1975, Bagley and Grau 1979).