Nelson and Hamer 



Chapters 



Nesting Biology and Behavior 



(3) buzzing, which includes single birds flying through the 

 canopy making continuous low-pitched buzzing wing sounds. 

 Several flight behaviors above the canopy are also 

 indicative of nesting. Like other alcids, Marbled Murrelets 

 are often observed circling singly or in groups above the 

 nesting grounds (Gaston 1992). Nesting birds may join with 

 others before returning to the ocean after incubation and 

 feeding visits. Nonbreeders may also accompany nesting 

 birds in these circling flights above the canopy. Murrelets 

 also occasionally create a loud sound, like a jet, during a 

 shallow or steep dive that often originates above the canopy 

 and ends at or below canopy level (Nelson and Peck, in 

 press; S.W. Singer, pers. comm.). In Oregon, this behavior 

 has been observed most often (67 percent) associated with 

 known nest trees. In California, the jet dive during encounters 

 between two murrelets has been observed and may be an 

 aggressive posture or territorial defense. 



Predator Avoidance Behavior 



The Marbled Murrelet's primary defense against predators 

 at the nest is to avoid detection through their secretive behavior 

 at or near the nest, morphological defense mechanisms, such 

 as cryptic plumage, and location of nest sites in trees and 

 stands with hiding cover. In direct response to calls, 

 silhouettes, or the presence of predators, and other disturbances 

 (e.g., airplanes) at nests, adults and chicks often flatten 

 themselves against the tree branch, holding their backs and 

 heads low and remaining motionless (Kerns, pers. comm.; 

 Naslund 1993a; Nelson and Peck, in press; Quinlan and 

 Hughes 1990; Simons 1980; Singer and others 1991). 

 However, they may also attempt to defend themselves against 

 predators that have located the nest. At a nest in California, a 

 murrelet chick was observed to defend itself against a Steller's 

 Jay (Cyanocitta stelleri) by standing erect, turning to face 

 the intruder, and jabbing it with its slightly open bill (Naslund 

 1993a; S.W. Singer, pers. comm.). In addition, Naslund 

 (1993a) noted that occasionally when a raven flew by a nest, 

 the adult assumed an erect posture as if readying itself to 

 take flight. S.A. Singer (pers. comm.) observed an incubating 

 adult lunge with open bill at a raven as it approached the 

 nest, causing it to veer off instead of landing. 



Vocalizations and Wingbeats 



Marbled Murrelets primarily give soft or muted calls 

 from the nest limb that are not audible from the ground. 

 They rarely give loud vocalizations from stationary locations 

 or in close proximity to a nest. When loud vocalizations are 

 given at or near a nest, they can be heard from the ground 

 depending on weather conditions and the location of the 

 observer. However, because loud calls are uncommon, using 

 them as a means for locating nests is not feasible with our 

 current understanding of murrelet vocalizations. 



Below is a summary of the vocalizations heard from 

 murrelet nests. Most of these vocalizations were heard with 

 the aid of microphones and other recording equipment pointed 

 directly at the nest branch. 



Adults and chicks were heard giving soft vocalizations 

 at most nests (n = 14), but loud vocalizations were heard at 

 only seven nests. These calls were given during incubation 

 exchanges and feeding visits. Soft vocalizations include groan 

 or grunt calls (duck-like quacks; previously referred to as 

 alternate calls), whistle calls, and faint peeps. Loud 

 vocalizations consist of keer and groan calls (Nelson and 

 Peck, in press). 



During incubation exchanges in Alaska, Oregon, and 

 California, vocalizations were primarily given at the nest as 

 birds arrived or departed the nest limb or during the brief 

 seconds when adults were on the nest limb together. However, 

 an interesting long (13.5 sec) vocal sequence was recorded 

 at one nest in Oregon. First, the incubating adult made soft 

 groans from the nest branch, and at the same time a second 

 adult flying nearby gave short, loud whistle calls. The 

 incubating adult then emitted additional groans, which became 

 increasingly louder and more emphatic. As the flying adult 

 joined the other on the nest limb, one of these two birds gave 

 loud whistle calls. 



The frequency of exchanges with vocalizations varied 

 among nests. In Alaska, 10 of 1 1 incubation exchanges 

 included soft groan and other (undescribed) calls; and adults 

 gave 1-2 loud keer calls when arriving or departing during 

 incubation exchanges on two of 12 mornings (Naslund, pers. 

 comm.). In Oregon, only 10 percent of incubation exchanges 

 included soft or loud vocalizations (n = 59). At a nest in 

 California, adults gave loud, emphatic "keer" and groan 

 calls just before leaving the nest branch on five of 17 

 incubation exchanges (Naslund 1993a; Singer and others 

 1991; S.W. Singer, pers. comm.). In addition, several soft 

 grunt calls, sounding like "unh-unh-unh", were heard on one 

 occasion after an adult landed on the nest branch. 



During feeding visits in Oregon, Washington, and British 

 Columbia, adults occasionally gave loud keer calls and soft 

 groan and "eeeuh" or "eeea" whistle calls as they flew from 

 the nest branch or while bringing food to a chick at the nest 

 (Hamer, unpubl. data; P. Jones, pers. comm.; Nelson and 

 Peck, in press). The latter calls sounded like a muffled 

 honking that adults gave while holding fish during feeding 

 visits. In addition, in California, a series of soft "chip" notes, 

 duck-like quacks, or short, soft grunts were given after the 

 adult bird arrived to feed the chick (Singer and others 1991; 

 S.W. Singer, pers. comm.). In British Columbia, a one-note 

 bleating call (soft groan) was usually made when two adults 

 were at the nest simultaneously (n = 4 occasions at 1 nest). 



Chicks emit a rapid, high pitched begging call during 

 feeding sessions. This begging call was recorded from a 

 captive chick, and heard or recorded from active nests in 

 Oregon and Washington (n = 4). In addition, P. Jones (pers. 

 comm.) described a soft peep or begging call (repeated 

 "puli-puli") that may have been given by the chick during 

 feedings at a nest in British Columbia. We believe begging 

 calls occur during every food delivery, but this sound is not 

 usually audible, especially without microphones placed at or 

 near the nest. 



USDA Forest Service Gen. Tech. Rep. PSW-152. 1995. 



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