WE ST SEN BLUEBIBD 621 



into its stomach to permit of further feeding. Thus the day is spent, 

 alternately in feeding and digesting. 



The mistletoe berrj^ consists of three parts, a central hard coated 'seed' 

 containing the plant embryo, a soft sticky pulp surrounding this seed, 

 and a thin enclosing 'shell.' It is the middle part, the mucilage-like pulp, 

 which the bluebirds seek as food. The berries which are eaten are not 

 entirely consumed ; were that the case the bluebird could be commended 

 highly for aiding in the control of an obnoxious parasite. But when the 

 berries pass through the bird's alimentary tract the digestive juices merely 

 dissolve oif the soft outermost layers. The central, harder part of the 

 berry is voided without its germinative powers being harmed in the least ; 

 'it also still retains a film of mucilaginous material and this causes it to 

 adhere to whatever it happens to touch. 



A means is thus afforded, and often operates, whereby the bluebird, 

 incidentally of course, acts as an agency for the dissemination of mistle- 

 toe seeds. It is easily conceivable that should the bird chance to perch 

 in a tree not previously parasitized by mistletoe the dropping of one or 

 more seeds on the branches would afford opportunity for the plant to gain 

 a start in that tree, providing the seed of the oak-tree mistletoe fell on an 

 oak, or that from a conifer fell on another of its ovra kind of host. Not all 

 the seeds by any means germinate and start a growth ; for the conditions 

 of germination must be just right in a number of concurrent respects. 

 But by the very abundance of the berries and the continued patronizing 

 of them by the birds it is likely that some new growths are started each 

 year. 



The mistletoe not only interferes immediately with the thrifty growth 

 of the host tree, but it opens the way for earl}^ decay of the affected 

 branches so that the wind and heaA'y snow of winter break them down — 

 a calamity from many standpoints. It is fair to inquire here whether 

 repressive measures should not be taken against the bluebird in an effort 

 to save the trees. To this we would say decidedly no, and for the following 

 reasons. 



The relation between trees, mistletoe, and bluebirds is an ancient one, 

 arrived at during eons of adjustment ; a state of approximate equilibrium 

 has been reached between the three. The fortunes of individual members 

 of the trio may vary from time to time, but no great change is likely to 

 occur, with general conditions of climate as they are. Furthermore, it is 

 doubtful if any intervention by man could be of lasting effect. The 

 Western Bluebird is but one of a number of birds which stand in practically 

 the same relation to mistletoe, and if the former were to be eliminated 

 some other species, such as the Cedar Waxwing or the Townsend Solitaire, 

 would likely take its place. It would be impractical — indeed, we believe. 



