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 16 THE CONDOR Vol. XV but I did take down, after the builders had left, some o.f the'nests fr m the cabin for examination and photography, and noted no parasites of any sort. Most animal parasites will not live for any length of time on any host other than the natural one, though some have several hosts, and a few seem quite 'in-' different in such matters. What the case is with the swallow bed-bug I do not know. I would suggest to my readers that in such cases as may come to their notice they secure specimens of the bugs and submit them to an expert for identi- fication. Certainly the matter will bear further investigation. Incidentally I may remark that it is worth while to collect any parasites bne may find on any animal and turn them over to some one interested in these things. I have made it a point lately to always have a few vials containing weak alcohol with me when collecting, and putting into them the parasites which often immediately show on a dead, animal, with a label to show from what species they were taken. I must express my appreciation of Mr. Dawson's courtesy in writing me &bout the matter instead of correcting me in the CoNuoR, which he would have bee n justified in doing under the circumstances as lnown to him. As it happens, in a way we were both right and both wrong, so we should both be satisfied. NOTES ON SOME FRESNO COUNTY BIRDS By JOHN G. TYLER Recurvirostra americana. Avocet. I N PURSUING ornithological sudies the bird student is often led to wonder what strange economy of Nature causes certain species to choose an en- vironment that, from a human standpoint, would seem unsuited to a creature of gentle disposition and attractive plumage. Several miles southwest of Caruther , Fi'esno 'County, California, are a number of shallow ponds of greater or less extent, according to the amount of winter rainfall, and all btlt two of them possessed of a freakish tendency to be.- come entirely dry at times, only to fill up again without warning. Surrounded by salt-grass knolls, their borders entirely devoid of vegetation of any kind, these ponds are not the most picturesque places in the valley. especially in view of the fact that the water is alkaline and in summer often becomes stagnant. A more foul-smelling, unattractive place could hardly be found, yet these ponds are re- sorted to each spring by a company of Avocets that remains throughout the summer., It is evidently a matter of choice rather than necessity with these handsome waders, too, for there are numerous overflowed pastures and per- manent ponds in other parts of the valley, each of which claims its nesting colony of Stilts every spring; but while a few of the latter may ofttimes be found with their larger cousins, yet I have never found the A'vocets elsewhere than in the immediate vicinity of the most sterile sinks. When the water in these ponds is subjected to the rays of the summer sun, a slimy, jelly-like substance appears around the edges and attracts myriads of flies, which often form an unbroken black band four feet or more in width and completely encircling the ponds. Is it not possible that these flies are one of the staple articles of food with the big waders ? Possibly this is the solution of their attachment to these uninviting ponds. A Similar assemblage of flies has been previously noted by Walter K. Fisher (Corn)oR, v, 9o2, p.. 9) as occtlrring at Mono Lake.