Location and Description of a Marbled Murrelet Tree Nest Site in Alaska

Little is known about the nesting habits of Marbled Murrelets (Brachyramphus marmoratus) even though they are widely distributed and locally abundant in nearshore waters of the North Pacific from central California to the Aleutian Islands, and from northern Japan to Kamchatka (Sealy 1975, AOU 1983, Scaly and Carter 1984).Onlv 14 nests of Marbled Murrelets.(exeluding the one reported here) have been documented (Dayetal.1983;CarterandSealy 1986,1987; Nechaev 1986: Labzvuk 1987).These include eight around nests (Ornithological Society of Japan 1975, SFmons 1980, Day et al. 1983), one ground nest in a shallow cavity (Johnston and Carter 1985), four tree nests (Kuzyakin 1963, Binford et al. 1975, Nechaev 1986, Labzyuk 1987), and one nest of unknown type (Anonymous 1927).Circumstantial evidence exists that tree nesting may be more common than existing nest records indicate.Downy young and fledgling Marbled Murrelets have fallen from trees and have been found in forested areas in southerly parts of their breeding range (Guiguet 1956.Harris 1971.Savile 1972.Singer and Verado 1975; Carter and Scaly 1987).Also, Scwls et al. (1980) observed that, in California, Marbled Murrelets were most abundant at sea adjacent to coastlines of mature coniferous forests.All discoveries of Marbled Murrelet nests, prior to this study, were fortuitous.Intuitively, ground nests seem more likely than tree nests to be discovered by accident (Day et al. 1983).To accurately establish the nest-site characteristics and nesting habitat preferences of Marbled Murrelets, additional nests must be located by some means that would not be biased toward ground nest sites.We attempted to locate Marbled Murrelet nest sites by capturing and radio tagging murrelets at sea during the nesting season, with the intention of tracking tagged birds to their nest sites.We describe a Marbled Murrelet nest site located in a tree on 11 June 1984.STUDY AREA AND METHODS This study was conducted at Kelp Bay (57"18' N, 134"55' W), located on the northeastern side of Baranof Island in southeastern Alaska.Kelp Bay is approximately 70 km2 and consists of three major arms and a bay.It is surrounded by steep mountains rising 6 10 to 1,280 m above sea level.The mountains are forested by old-growth (uneven-aged, virgin stands of) Sitka spruce (Picea sitchensis), western and mountain hemlock (Tsuga heterophylla, T. mertensiana), and Alaska cedar (Chamaecyparis nootkatensis).About 4 km* of forest were clear-cut in 1976 and 1977.Outside the logged areas, large (>0.5 m dbh, > 15 m tall) trees occur below 366 m, while small stunted or shrublike trees extend to tree line at 457 to 762 m.The mountain tops are alpine tundra which is covered by snow for most or all of the year.Fieldwork was conducted 11 May to 17 June 1983 and 4 May to 13 June 1984 to coincide with estimated dates of nest establishment and incubation based upon estimated nesting chronology in British Columbia (Sealy 1974).We captured murrelets using a net gun, and attached 1 O-g radio tags (transmitter, lithium battery, and coiled antenna in an epoxy resin potting) developed by Advanced Telemetry Systems, Bethel, Minnesota.We glued the radio tags to the birds' back feathers, between the wings, using waterproof "Devcon two-ton, epoxy."We searched for radio-tagged birds from a boat using a Telonic TR-2 receiver with an H-Adcock antenna-mounted on a 2-m pole, and using a Cessna 185 fitted with an H-Adcock antenna.More details on capture and radio-tagging techniques are provided in Quinlan and Hughes (in press). RESULTS AND DISCUSSION NEST LOCATIONWe captured and radio tagged 17 murrelets during our study (eight in 1983 and nine in 1984).We were only able to track one bird to a site on land (Fig. 1).We originally tagged the bird on 18 May 1984, and relocated it on the water on 19 and 2 1 May.On 22 May we picked up its signal from a location on land while radio tracking from a boat.The signal was detected emanating from the same on-land location on 22, 24, 26,30 May, and 7 June.On 23 and 27 May, we located the bird on the water 2.4 and 3.2 km (straight-line distance) from the site where we later located the nest.