192 THE WILSON BULLETIN— December, 1921 



poned until these birds are in full niiuration uuinerous 

 earlier migrauts will have ])asse(l through or will be rep- 

 resented merely by stragglers. Occasionally migration is 

 delayed in such a way that ordinarj^ migrants are here in 

 numbers at the same time as the later ones. Theoretically, 

 such conditions afford the greatest opportunity for a long 

 bird list. The writer has made only one trip at such a 

 time, and not realizing the opportunity in advance, the 

 route taken was entirely in one type of country v/here 

 there was little chance of seeing marsh and aquatic birds. 

 This was ou the 30th of May, 1017 (valley of Patuxent, 

 above Laurel, Md., in company with Alex. Wetmore and 

 Douglas C. Mabbott) and 78 species of birds were seen. 

 Among them were four species not recorded in any of the 

 lists here discussed, namely, Lincoln's sparrow, tlie Ten- 

 nessee warbler, Philadelphia vireo, and yellow-bellied fly- 

 catcher. The last-named was actually common. 17 individ- 

 uals being seen. On the annual spring excursions here 

 analyzed only one mourning warbler had been observed, 

 but on this da}' we saw six. Specimens of this species, 

 the yellow-bellied flj^catcher and Philadelphia vireo were 

 collected. A ver\^ good list (20 species) of warblers Avas 

 made, the records being very late for the Cape May, 

 black-throated blue, myrtle, magnolia, chestnut-sided, bay- 

 breasted, and Tanada warblers, and the olise-backed and 

 and gray-cheeked thrushes. Taking advantage of the reve- 

 lations of this day various observers made bird trips in the 

 next few days, with the result that the year 1!)17 furnished 

 a larger number of latest dates for migrants than any otlier. 

 With a delayed (and therefore condensed) migration real- 

 ized, an all-day trip made over tlie best route in the region 

 shouhl give most gratifying results. What an op])ortunity 

 there was, for instance, during the " tidal wave " of birds 

 as described by Cones and Prentiss * for the second and 

 tliird Aveeks of May, 1SS2, when even the trees in the city 

 l)aiks and streets were swarming with warblers and otlier 

 brightly colored migrants. If such a ])henomenon occurs 

 again let us hope tliat Washington observers make tlie 

 most of it. 



* Avifauna Columbiana, 1883, pp. 31-32. 



