84 



Gilbert S. Grant 



Table 2. Surface area of rete and body weight ratios of 1 1 species of Atlantic Procellarii- 

 formes. Data presented as mean ± 1 standard deviation (sample size). 











Average 





Rete surface 



Weight of 



Surface area/ 



breeding 



Species 



area (mm 2 ) 



birds (g) 



weight (mm 2 /g) 



latitude 



Northern Fulmar 











Fulmarus glacialis 



35.10±0.92(2) 



692.3±78.5(20) a 



0.05 



67° N 



Antarctic Petrel 











Thalassoica antarctica 



28.60(1) 



639 b 



0.04 



74° S 



Black-capped Petrel 











Pterodroma hasitata 



32.11±6.21(5) 



431.1±47.1(5) 



0.07±0.01(5) 



17°N 



Cory's Shearwater 











Calonectris diomedea 



31.45±3.18(13) 



568.8±80.6(12) 



0.06±0.01(12) 



27° N 



Greater Shearwater 











Puffinus gravis 



36.08±1.50(4) 



626.6±29.9(3) 



0.06±0.01(3) 



38° S 



Sooty Shearwater 











Puffinus griseus 



36. 18± 1.35(3) 



774.0(l) a 



0.04 



54° S 



Manx Shearwater 











Puffinus puffinus 



26.00± 1.84(2) 



359.2±34.0(2) 



0.07±0.01(2) 



47° N 



Audubon's Shearwater 











Puffinus Iherminieri 



14.67±1.98(7) 



179.8± 4.4(6) 



0.08±0.01(6) 



22° N 



Wilson's Storm-Petrel 











Oceanites oceanicus 



3.4910.77(8) 



34.3± 2.9(6) 



0.10±0.02(6) 



63° S 



Leach's Storm-Petrel 











Oceanodroma leucorhoa 



3.90(1) 



40.8(1) 



0.10(1) 



53° N 



Band-rumped Storm-Petrel 











Oceanodroma castro 



4.55(1) 

 



48.4(1) 



0.09(1) 



35° N 



a from Platania et al. (in press 





mean of values in Brown et al. 1982 









serve to maintain brain temperatures lower than core body temperatures 

 during heat stress (Kilgore et al. 1979; Bernstein et al. 1979a, b). During 

 cold stress the arterial blood flowing to the anterior surface of the head 

 is cooled by returning venous blood in the RMO (Frost et al. 1975). 

 Undue loss of body heat is prevented in the RMO by counter-current 

 heat exchange. In this example, the anastomoses with the intracranial 

 arteries are not open; blood flow to the brain is achieved directly via the 

 internal carotid. Therefore, the lack of correlation between size of RMO 

 and latitude (as an indicator of temperature stress) may indicate that the 

 RMO functions during both cold and heat stress. The relatively larger 

 RMO in smaller birds is probably related to their relatively larger sur- 

 face/volume ratios, and the relatively greater stress they encounter as 

 environmental temperatures fluctuate. 



