76 



Henshaw on Birds observed in Nerv Mexico. [Jnmiary 



III this locality at least there is an evident reason lor this. Just about 

 this date the Scrophularia, which is the favorite food plant of the Hum- 

 mers, begins to lose its blossoms, and in a comparatively short time the 

 flowers give place to the seed pods. Though there are other flowers which 

 are resorted to by the Hummers, particularly several species of Penste- 

 mon, they by no means aftbrd the luxurious living the former plant 

 does. It seems evident, therefore, that the moment its progeny is on the 

 wing, and its home ties severed, warned of the approach of fall alike by the 

 frosty nights and the decreasing supply of food, off go the males to their 

 inviting winter haunts, to be followed not long after by the females and 

 j-oung. The latter — probably because they have less strength — linger 

 last, and may be seen even after every adult bird has departed. 



55. Selasphorus rufus. Rufous-backed Hummer. — The number of 

 representatives of this and the preceding species that make their summer 

 homes in these mountains is simply beyond calculation. No one whose 

 experience is limited to the Eastern United States can form any adequate 

 idea of their abundance. They occur from an altitude of about 7500 feet 

 far up on the mountain sides, as high up, in fact, as suitable flowers aftbrd 

 them the means of subsistence. They are most numerous at an altitude 

 of from Sooo to 9000 feet. During the entire summer they frequent almost 

 exclusively a species oi Scrofhtclaria which grows in clumps in the sun- 

 nier spots of the valleys. From early dawn till dusk the Hummingbirds 

 throng around these plants intent in surfeiting themselves on honey and 

 the minute insects that the honey attracts. The scene presented in one of 

 these flowering areas is a most attractive one. Males and females all flock 

 to the common feeding ground, and as the Hummers, especially of the Ru- 

 fous-backed species, are pugnacious and hot tempered in the extreme, the 

 field becomes a constant battle-ground whereon favorite flowers and favorite 

 perching grounds are contested for with all the ardor that attaches to 

 more important conquests. The fiery red throat of the Rufous-backed 

 Hummer is an index of its impetuous, aggressive disposition, and when 

 brought into conflict with the other species it invariably asserts its 

 supremacy and drives its rival in utter rout from the fields. Nor do the 

 males of this species confine their warfare to their own sex. Gallantry has 

 no place apparently in their breasts, and when conquest has put them in 

 possession of a perch near a clump of flowers they wage war on all comers, 

 females as well as males. 



Nor is the pugnacity of this Hummingbird limited to attacks on other 

 species. The presence of a male of its own kind is suificient to arouse it to 

 the highest pitch of fury, and should the contestants be equally matched 

 they will seize each other by the bill and, using their wings as offensive 

 weapons, fall to the ground, roll over and over in fierce strife until 

 exhausted, or until one is worsted, when he is oft" like a bullet for less dan- 

 gerous hunting grounds, followed by the exulting victor, who, however, 

 soon gives over pursuit and returns to the perch he has so well won, to 

 preen his disordered plumage and make ready for a fresh contest. 



When the attack is urged against the males of the Broad-tailed species 



