its greatly developed spatules serve in 

 some way to sustain it in the air; and 

 if so this may account for the very 

 diminutive size of its wings. It is just 

 possible that, when the tail is fully 

 spread, the spatules may be project- 

 ed in front of its head. 



In the next hinidred years few 

 biologists even reached the re- 

 mote mountains, let alone recorci- 

 ed encounters with the extraordi- 

 nary hummingbird. The species 

 was all but forgotten until the 

 1960s, when the Brazilian collec- 

 tor Augusto Ruschi managed to 

 add a live male to his aviary. Even 

 then, enthusiasts were reluctant to 

 travel to Peru because of the na- 

 tion's poHtical turmoil. Not until 

 the early 1990s, when conditions 

 became more stable, did they be- 

 gin flocking to see what had come 

 to seem a nearly mythical creature. 

 To this day, its nest has not been 

 scientifically described, no major 

 studies of the species have been un- 

 dertaken, and only a few people 

 have been able to photograph the 

 bird in its native habitat. 



I've already noted how hard it is to 

 observe a spatuletail in flight, because 

 the enormous paddles move in differ- 

 ent directions, diverting attention from 

 the bird itself. I couldn't help wonder- 

 ing whether the tail evolved because it 

 enabled the bird to avoid predators or 

 harassment from other hummingbirci 

 species. But the accepted explanation 

 for the male's tail is that it plays a key 

 role in courtship, and therefore has 

 been shaped through the process 

 known as sexual selection. 



In some ways, sexual selection seems 

 perversely at odds with the interests of 

 the bird. To construct its monumental 

 tail, the male must divert valuable 

 resources toward a body part that 

 contributes nothing to its ability to 

 compete for food. Moreover, the tail 

 actually hampers its ability to fly, there- 

 by iiicrcasiii}^ its risk of becoming prey. 

 But if females prefer mates with fancy 

 tails or other seemingly useless attrib- 

 utes, a male with such an attribute is 

 more likely to mate and produce otT- 



Lithograph of the marvelous spatuletail, made by the 

 English artist and naturalist John Gould in the mid- 

 nineteenth century, was based on a single dead 

 specimen. In his scientific description. Could incorrectly 

 surmised that the tail feathers aided the bird in flight. 



spring. That is the true measure of the 

 male's Darwinian "fitness." The male 

 peacock's tail is commonly cited as an 

 extreme case of sexual selection. 



But why do females — with their 

 own interests in producing off- 

 spring — choose such extravagances in 

 looking for a suitable mate? One ex- 

 planation is that females are on the 



hummingbird (booted racket- 

 tail, racket-tailed coquette) and in 

 most species of motmots. Else- 

 where, they occur in racket-tailed 

 parrots from the Philippines, in 

 paradise-kingfishers from the 

 Australo-Fapuan region, and in a 

 few drongo species from South 

 Asia and Southeast Asia. The pen- 

 nant-winged nightjar, a nocturnal 

 African species, has a single rack- 

 et flight feather toward the end of 

 each wing; the feather drops off 

 after the courting season. Among 

 the Parotia, a genus of birds-of- 

 paradise from New Guinea, six 

 racket plumes sprout from the 

 head and play an important role 

 in the male's display. 



The development of racket 

 feathers is similar in most species. 

 The shaft of a more ordinary 

 feather bears long barbs along two 

 sides, from which branch smaller 

 barbules. In the racket of a spat- 

 uletail, except for the disk at the 

 end, the feather shaft bears only 

 short barbs — indeed, it looks al- 

 most bare to the naked eye. One ex- 

 ception is the racket in motmots: the 

 feather begins its growth like a normal 

 feather, but the barbules and barbs near 

 the base gradually wear out and fall off, 

 or are plucked off as the bird preens. 



I 



lookout for evidence of a male's vig- 

 or. If a male can devote so much ex- 

 tra energy to decoration or to some 

 special courting behavior, his out- 

 landish distinction may be a fair ad- 

 vertisement of a reserve of energy. But 

 once a pattern is set — say, the females' 

 preference for a larger tail — it tends to 

 take on a life of its own, as males com- 

 pete from generation to generation for 

 the attention of the opposite sex. 



Spatules ar 

 Peruvian 



are not exclusive to this 

 hummingbird. Evolu- 

 tionary forces have shaped them in a 

 number of species belonging to vari- 

 ous bird families. In the Americas, tail 

 rackets occur both in other species of 



n the avian world, it's common for 

 a few adult males to gather in a com- 

 munal display area called a lek where 

 they strut their stufFbefore the females. 

 Spatuletail males in a lek usually out- 

 number the females that come in hope 

 of finding Mr. Right. Young males, still 

 learning the art of courtship, also hang 

 around the lek. 



Roger Ahlman, a birder and freelance 

 tour guide who lives m Ecuador, once 

 watched an adult male spatuletail that 

 was perched on a branch, waving his tail 

 feathers from side to side. A second fi-iU- 

 plumaged male was perched not far 

 away, and a young male made a brief 

 appearance. A female then entered the 

 stage and sat on the same branch as the 

 first male. In response he launched into 

 full display mode: He flew upward. 



26 



NA I URAL IIIS IORY February 2006 



J 



