Hamer and Nelson 



Chapter 6 



Characteristics of Nest Trees and Nesting Stands 



tree bole height. Nests in Alaska were also located high up 

 the tree bole with a mean of 59 percent. Positions of the nest 

 on the tree bole for all nests throughout the range of the 

 Marbled Murrelet showed that the top 10 percent of the tree 

 was not utilized to any great degree, with a maximum number 

 of nests located 70-80 percent up the tree bole (fig. 6). 



The majority of nest limbs in the Pacific Northwest (n = 

 44) were oriented toward the south or the north. Forty-four 

 percent of the limbs faced a southerly direction ranging 

 between 136 and 225 degrees (table 3). Another group of 

 nests (26 percent) were oriented in a northerly direction 



ranging between 316 and 45 degrees. Nest limbs oriented 

 toward the east or west consisted of 14 percent and 16 

 percent of the sample respectively. 



Nest Characteristics 



Nest cups were located a mean distance of 89 cm from 

 the tree bole for nests in the Pacific Northwest (table 3). Here, 

 a total of 7 1 percent of the nests were located within 1 m of 

 the tree bole. This relationship was also true for nests located 

 throughout the North American range (fig. 7), as 5 1 percent 

 of the nests were located within 40 cm of the tree trunk. 



10 



6 8 10 



NUMBER OF NESTS 



12 



14 



16 



Figure 6 The relative vertical positions of Marbled Murrelet nests in relation to 

 the heights of the tree bole for 59 tree nests found in North America. 



24 



I \..L 



60 100 140 180 220 260 300 340 '/ 762 

 NEST DISTANCE FROM TRUNK (cm) 



Figure 7 Nest distances from the tree trunk for 57 Marbled Murrelet nests found 

 in North America. The number of nests was listed in 20-cm increments beginning 

 with nests found 0-20 cm from the tree trunk 



78 



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



