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Page:Popular Science Monthly Volume 54.djvu/801

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THE COMING OF THE CATBIRD.

Delaware from the west. The last two places to report arrivals were situated farther up the river and some distance back from it. All this confirms the general idea that in migrating most, if not all, of the various land birds follow river valleys and invade the upland districts, lying back from either side, by way of the smaller tributaries.

1885. 1886. 1887. 1888. 1889. 1890. 1831. 1892.
Flicker April 10 Mar. 24 Mar. 26 Mar. 30 Mar. 28 Mar. 26 Mar. 30 April 2
Chimney swift April 22 April 23 April 22 April 20 April 15 April 22 April 16 April 27
Hummingbird April 29 May 12 May 12 May 14 May 7 May 11
Kingbird May 6 May 11 May 7 May 6 May 6 May 14 May 1 May 4
Crested flycatcher May 2 May 12 May 3 May 1 May 8 May 1 April 30 May 3
Pewee April 3 Mar. 20 Mar. 21 Mar. 22 Mar. 27 Mar. 27 Mar. 31 April 3
Wood pewee May 6 May 15 April 30 May 13 May 12 May 14 May 6 May 17
Red-winged black-bird Mar. 4 Feb. 19 Feb. 19 Feb. 21 Mar. 13 Mar. 12 Feb. 25 Mar. 9
Meadow lark Feb. 10 Mar. 19 Mar. 21 Mar. 14 Mar. 12 Feb. 23 Mar. 17
Baltimore oriole May 5 May 4 May 2 May 2 May 7 May 1 May 1 May 3
Purple grackle Mar. 16 Mar. 7 Feb. 19 Feb. 21 Mar. 2 Feb. 13 Feb. 18 Mar. 6
Chipping sparrow April 8 April 9 April 8 Mar. 31 Mar. 29 April 8 April 13 April 4
Field sparrow April 11 April 7 April 9 April 2 Mar. 29 Mar. 13 Mar. 15 Mar. 26
Chewink April 22 April 23 April 27 April 18 April 11 May 1 April 18 April 24
Indigo bird May 16 May 11 May 7 May 12 May 12 May 10 May 8 May 10
Scarlet tanager May 9 May 12 May 5 May 8 May 9 May 4 April 28 May 3
Barn swallow April 22 April 19 April 21 April 12 April 22 April 19 April 19 April 24
Red-eyed vireo May 7 May 11 May 4 April 29 May 5 April 30 May 2 May 3
Black-and-white warbler April 30 May 4 April 27 April 21 April 20 April 30 April 24 May 1
Yellow warbler May 6 May 4 May 2 May 5 May 11 May 1 May 8 May 4
Myrtle warbler May 2 April 10 May 2 April 25 April 20 April 27 April 18 April 7
Black-throated green warbler May 2 May 11 May 5 April 26 May 5 May 2 April 19 April 30
Ovenbird April 30 May 3 April 29 April 30 May 3 May 3 April 29 April 30
Maryland yellow throat April 29 April 24 April 28 April 30 May 6 April 30 May 1 May 3
Chat May 2 May 12 May 5 May 5 May 11 May 5 May 10 May 3
Redstart May 2 May 4 May 3 May 1 May 4 May 3 April 29 April 30
Catbird May 2 May 4 May 3 May 5 May 5 May 5 May 4 April 30
Brown thrasher April 24 April 25 April 28 April 15 April 22 April 30 April 19 April 30
House wren May 3 April 27 April 24 April 28 April 14 April 30 April 19 May 5
Wood thrush May 2 May 1 May 1 May 1 May 3 April 30 April 23 May 2
Veery May 11 April 25 May 3 May 6 May 2 April 28 May 4
Hermit thrush April 13 April 7 April 9 April 3 April 10 April 13 April 12 April 3
Robin Mar. 7 Mar. 10 Feb. 28 Feb. 19 Mar. 7 Feb. 26 Feb. 24 Mar. 9
Bluebird Mar. 18 Feb. 17 Feb. 21 Mar. 8 Feb. 23 Feb. 17 Mar. 9

The fact of greatest importance resulting from these observations was that relating to temperature. It was found that there was always a marked increase in the number of individuals of a given species following a warm wave of temperature as marked by a decided rise of the thermometer. The following graphic representation, based on the abundance from day to day of three common and easily observed species—the brown thrasher, chipping sparrow, and flicker—affords an interesting illustration of the relative movements of the two waves. It will be understood that the numbers in the extreme left-hand column refer to the relative abundance of individuals of the three