TIME-ENERGY USE AND LIFE HISTORY STRATEGIES 



149 



gulls (Larus canus) are somewhat later 

 arrivals, and terns and a few parasitic jaegers 

 (Stercorarius parasiticus) are the latecomers 

 to Barents Sea colonies (Belopol'skii 1961). 



The timing of the season (as illustrated in 

 Fig. 5) varies widely among localities, and be- 

 cause of local weather patterns and ocean cur- 

 rents, this variation can be unrelated to lati- 

 tude (Belopol'skii 1961). Examples of such 

 variation are also known in North America: 

 for instance, Leach's storm-petrels in Alaska 

 lay eggs 2 to 3 weeks later than do those in 

 California (Harris 1974); however, the details 

 of timing are largely unknown for many 

 species in this region. Progression of thaw, 

 which also varies from year to year, causes 

 variation in the timing of the breeding season 

 (Belopol'skii 1961; Evans and McNicholl 

 1972). Fig. 6 shows the diversity in start of 

 the breeding season for different species on 

 the same island in the Barents Sea as well as 

 variation in time devoted to various compo- 

 nents of the reproductive cycle. 



THICK-BILLED MURRE 



45 

 55 

 70 



BLACK-LEGGED KITTIWAKE 



Fig. 5. Differential average arrival on breeding 

 grounds and average duration of prenesting 

 period of thick-billed murres (Una lomuia) and 

 black-legged kittiwakes on various colonies in the 

 Barents Sea. From Belopol'skii (1961). Length of 

 prenesting period in days (shaded bars) indicated 

 on right. Letters represent locations as follows: A 

 = Novaya Zemlya, Kara Straits; B = Novaya 

 Zemlya, Karmakuly Bay; C = Franz Josef Land; 

 and D = East Murman. 



Prenesting Activities 



Some species are apparently able to delay 

 maturity of sexual organs until environ- 

 mental conditions are suitable for nesting 

 e.g., burrow and crevice nesters in the 

 Barents Sea do not become sexually mature 



until snowmelt (Belopol'skii 1961). Many 

 others, however, reach sexual maturity soon 

 after arrival on the breeding grounds, and a 

 few (such as jaegers and kittiwakes) mature in 

 migration or on the wintering grounds (Belo- 

 pol'skii 1961). Northern phalaropes (Lobipes 

 lobatus) sometimes lay eggs as early as 

 1 week after arrival (Hilden and Vuolanto 

 1972). This factor, in combination with timing 

 of arrival, affects the amount of time spent in 

 prenesting activities (Fig. 6). Most species 

 gain weight during this period (Belopol'skii 

 1961), and the time required for each species 

 to reach full breeding condition must also de- 

 pend on feeding conditions and the state of 

 the bird on its arrival at the nesting site. 

 These factors help explain why early arriving 

 species are not necessarily early nesters 

 (Fig. 6). 



PRE-LAYING 



INCUBATION NESTLING 



SLACK GUILLEMOT 



I I I 



COMMON PUFFIN 

 MEW GULL 

 PARASITIC JAEGER 

 COMMON EIDER 

 ARCTIC TERN 



Fig. 6. Variation in timing of events in the reproduc- 

 tive cycle of Barents Sea seabirds nesting on the 

 same island. Data from Belopol'skii (1961). 

 Shaded bars at left indicate the prelaying 

 periods, open bars the incubation periods, and 

 shaded bars at right the portion of the growth 

 period in which the chick remains at the nest site. 

 Total length of time indicated is about 6 months. 



Aside from nest building, most prenesting 

 activity consists of courtship and territorial 

 behavior. These activities have been well de- 

 scribed for representative seabird species, but 

 because assessments of time and energy de- 

 voted to them have been almost completely 

 neglected, they are not discussed further here. 

 For examples, see accounts in Gross (1935) for 

 Leach's storm-petrel; Tinbergen (1935), 

 Bengtson (1968), Hbhn (1971), and Howe 

 (1975) for phalaropes; Storer (1952) for com- 

 mon murre, Una aalge, and black guillemot, 

 Cepphus grylle; Tschanz (1959) for common 

 murre; Brown et al. (1967) for Sabine's gull; 

 Tinbergen (1960) for herring gull; McKinney 



