We use a hot iron in two ways. For temporary marks that last 

 through one season, but that may not be readable in the following 

 season, we use the iron to singe away the guard hair, leaving the 

 lighter underfur exposed. Once the equipment is set up, this '•hair- 

 branding" technique is very fast for marking large numbers of ani- 

 mals. The cleanest marks result from branding wet animals because 

 water pre vents the hair around the brand area from flaming . If equip- 

 ment is available this technique is preferable to hair clipping. 



Skin-branding requires more caution and attention to detail than 

 hair-branding. The very dense underfur absorbs large amounts of 

 heat from the branding iron and, when burned, this fur may cake up 

 to form a protective layer over the skin. We lightly singe the hair, then 

 brush away the caked ash with a glove or a stout brush until the 

 unburned underfur is visible. Then the still-hot iron is carefully reap- 

 plied to the same area, and hair is lightly singed again. Three or four 

 applications of the iron may be necessary before the iron contacts the 

 skin directly. A light, quick application of the iron to the skin is suf- 

 ficient for scarring. Occasionally the branding iron may have to be 

 reheated to its original cherry red color in order to penetrate to the 

 skin. Burning the underfur also produces dense smoke that obscures 

 the work area. Of 120 animals observed in 1978 which had been 

 skin-branded with letter/number combinations in 1977, we saw no 

 animals with inflamed wounds, though several of them had parts of 

 the marks missing because the branding iron had not penetrated the 

 underfur quite far enough. 



It is important that the burning surface of the branding iron be 

 curved in cross section, and have well-rounded edges. (We used 

 round stock for fabricating our brands.) Sharp corners can burn 

 quickly through the animal's skin to the flesh and leave long-lasting 

 open wounds. 



The location of pelage marks is important. Marks aligned over the 

 animal's spine are the easiest to apply but can only be read from 

 directly above, or if the animal lies on one side with its back directly 

 to the observer Such views are rare, so usually only part of the mark 

 is seen. Marks on the flanks can be obscured by other animals. Two 



identical marks, one on each shoulder high enough that they almost 

 touch at the mid-line of the back, are preferable. One mark or the 

 other can usually be seen from any angle except when the animal lies 

 on one side with its belly toward the observer In this position its flip- 

 per tags can usually be read. 



Whatever other marks are used, seals should also be given a spot 

 (by clipping or branding) on the head. Guard hair should be removed 

 in a circular patch 6-8 cm in diameter. In tightly packed groups of ani- 

 mals head marks are prominent and notify the observer to continue 

 watching the animal until its mark or tag can be read. These marks 

 have allowed us to identify a large number of animals that would 

 never have been located by pelage marks or flipper tags alone. We 

 now mark the heads of all animals we need to follow, regardless of 

 what other types of marks or tags we may apply. Adult males are 

 prominent enough without our applying head marks. 



Harnesses 



We use harnesses for attaching depth recording instruments to 

 seals (Kooyman et al. 1976), for moving seals in captivity, and for 

 securing special "chastity belts" to captive females during studies of 

 estrus (Fig. 6). Harnesses are made of tubular nylon "rope" available 

 in mountaineering stores. This rope lies flat like a double ribbon and 

 is 2.5 cm wide. It is flexible and light, yet strong, it will not kink if 

 rolled, and it is available in bright colors for easy visibility in the 

 field. The harness has one strap around the neck small enough in 

 diameter that it will not pass backward over the scapulae and front 

 flippers, the point of greatest girth in otariids. It has a chest strap pos- 

 terior to the front flippers which prevents the seal from backing out of 

 the neck strap. The neck and chest straps are attached ventrally by 

 two "belly" straps which prevent the harness from rotating around 

 the seal's body, and by a dorsal midline "back" strap. Harnesses that 

 carry instruments use a back strap made of stiff nylon belting material 

 5 cm wide. The neck and chest straps are adjusted to length by pass- 

 ing them through double "D" rings attached at the juncture of these 



Figure 6.— A harness around the neck and chest of an adult female fur seal used to secure a "chastity belt" during 

 experiments on estrus. The female is restrained by a hold-down bar. 



