Part 28

_Food._--Throughout most of the year the Cape May warbler is insectivorous, and mainly beneficial, but for a short time on its fall migration it undoubtedly causes damage to ripe grapes by puncturing them to obtain the juice, often ruining a large percentage of the crop. Many complaints have been made and several have been published. Frank L. Burns (1915a) claimed that about 50 percent of his crop was destroyed at Berwyn, Pa., and says: "I believe that grape juice was the principal food of the Cape May Warbler during its lengthy visit in this neighborhood. It was present in countless numbers at Berwyn and vicinity as far as a mile south of the village, apparently by far the most abundant species for a period; the complaints of the the 'little striped yellow bird' were many, and so far as I am able to learn, all unbagged grapes were ruined; the loss must have been many tons worth several hundred dollars." He sent ten stomachs to the Biological Survey for analysis and received the following reply:

Hymenoptera constituted on an average 57.5 percent of the contents of the stomachs. A third perhaps of this material was parasitic Hymenoptera and their destruction counts against the bird. The others were ants and small bees and are of neutral importance except perhaps the ants which may be injurious. Diptera made up 16.7 percent of the stomach contents and again a large proportion of them were parasitic species. Lepidoptera (small moths) constitute 16.7 per cent, beetles 7.8 percent and the remainder was made up of Hemiptera, spiders and miscellaneous insects. Except for the spiders the food was entirely composed of insects, and a large proportion of useful species were taken and no decidedly injurious ones. I should say that these Cape May Warblers did very little to pay for the destruction of grapes.

McAtee (1904), after investigating the damage done on grapes by this and the Tennessee warbler in Indiana, published the following report on the contents of a single stomach of a Cape May warbler:

8 _Typlocyba comes_, an especial pest of the grape, "an exceedingly abundant and destructive" jassid; 3 _Aphodius inquinatus_ and one Carabid, kinds which may be considered neutral economically, but, in case of a departure from their ordinary diet, would on account of vegetarian tendencies become injurious; 1 _Drasterias_ sp. (click-beetle), 1 tortoise-beetle, 1 flea-beetle (_Haltica chalybea_), all injurious beetles, the last of which is a particular enemy of the grape, which "appears on the vine in early spring and bores into and scoops out the unopened buds, sometimes so completely as to kill the vine to the roots," and later in the season in both larval and adult stages feeds upon the foliage, and if abundant "leaves little but the larger veins"; 1 _Notoxus_ sp., a weevil, with all the undesirability characteristic of the creatures bearing that name; 2 ants, harmful, if for no other reason than harboring plant lice; and a vespoidean hymenopteron (wasp) of neutral significance. * * *

The feeding habits of the birds may, from the present knowledge, be declared practically entirely beneficial. In return it seems not too much to expect that we should without complaint furnish, for a few days in the year, the drink to wash the great numbers of our insect enemies down to their destruction; and to consider these two little fellows as among the worthiest as they are among the prettiest of our warbler friends.

Prof. Maurice Brooks (1933), speaking of this warbler in West Virginia, says:

We had at that time [1909] a small commercial vineyard, and during the first week in September, when the crop was just ripening, we were surprised to find in the vineyard swarms of Cape May Warblers. We were not long in doubt as to their purpose there, for within a week they had destroyed practically every grape we had. * * * Their method was to puncture the skin of the berry at one point, extract a little juice, and move on to the next. They would systematically work over every berry in the cluster, if undisturbed, and they soon became exceedingly tame. It is no exaggeration to say that there were hundreds of the birds in the locality.

After the birds had made one puncture, swarms of bees and wasps soon finished the work of destruction. There was no way of frightening so many birds away, and we were driven to sacking our grapes in the future. The next year, 1910, they returned in numbers again, destroying practically all unsacked clusters, and completely cleaning out the vines of our neighbors, who raised just a few grapes for their home use.

These and other warblers have been seen drinking sap from the holes dug in trees by sapsuckers, but they also obtain some insects from such borings and perhaps also from the punctured grapes, which make fine insect traps. However, the damage does not seem to be universal, and occurs only where the birds are abundant, and then for only a short time. In view of his record as an insect destroyer, the laborer may be worthy of his hire.

To the insects mentioned as food for this warbler, A. H. Howell (1932) adds small crickets, flies, leaf hoppers, termites, larvae of moths, dragonflies, and daddy-long-legs.

_Behavior._--Brewster (1938) writes:

It keeps invariably near the tops of the highest trees whence it occasionally darts out after passing insects. It has a habit of singing on the extreme pinnacle of some enormous fir or spruce, where it will often remain perfectly motionless for ten or fifteen minutes at a time; on such occasions the bird is extremely hard to find, and if shot is almost certain to lodge on some of the numerous spreading branches beneath. * * * In rainy or dark weather they came in numbers from the woods to feed among the thickets of low firs and spruces in the pastures. Here they spent much of their time hanging head downward at the extremity of the branches, often continuing in this position for nearly a minute at a time. They seemed to be picking minute insects from the under surface of the fir needles. They also resorted to a thicket of blossoming plum trees directly under our window, where we were always sure of finding several of them. There were numerous Hummingbirds here also, and these, the Cape Mays were continually chasing.

While watching a pair at their nest building, Dr. Merriam (1917) saw a female on the ground gathering material; she "was attacked by a Junco and after a chase the Junco actually caught and held her. At this commotion the male Cape May flew down and lit close by but took no active part in the argument. The Junco was apparently victor for after one more flight to her nest the female Cape May was not again seen to trespass on the Junco's territory or do any more nest building that morning." However, in his notes from West Virginia, Dr. J. J. Murray says that "this warbler is more active and restless in its feeding than any of our warblers, except possibly the myrtle; and it is also noisier and more aggressive in its attitude toward other warblers which seek to share its feeding places." Harlow also says that "the male Cape May is the tiger of the north woods in defending his territory. He attacks all birds that come close to the nest, up to the size of the olive-backed thrush, and is absolutely fearless."

_Voice._--Aretas A. Saunders sends me the following note on the song of this warbler: "I have had few opportunities to study the song of the Cape May warbler, and have only five records. These show that the song is weak, high-pitched and somewhat sibilant. The notes are mainly all on one pitch, in even rhythmic time and from eight to eleven in number. They are pitched on E´´´´ and F´´´´. Two of the songs have one or two notes, near the end, a half-tone higher in pitch than the others. The songs are from 1-3/5 to 2 seconds in length."

Francis H. Allen (MS.) heard one singing and feeding in some Norway spruce in West Roxbury, Mass., on May 10. "He had _chip_ notes very much like a familiar note of the chipping sparrow. (I have also recorded a _prssp_ like that of the black-poll warbler but fainter and sometimes doubled.) This bird had a variety of songs. The simplest one resembled the black and white warbler's song and a short simple song of the redstart, but was thinner and harder in quality than the latter. Then there were other, more elaborate songs, some divided into two parts and some into three. Two or three times he sang several times with no pauses between, making what was practically a long continuous song. The chief characteristic of the songs, I should say, was short and staccato double notes, the latter part of which were very high-pitched. These repeated several times formed the simplest of the songs. The song in three parts reminded me of that of the Tennessee warbler, but was higher pitched and not so full and loud. The bird had long periods of silence, but sang freely when he did sing."

Brewster (1938) says that "the song of this Warbler is harder--or at least sharper and more penetrating--than that of either the Bay-breast or Blackburnian. In these respects it resembles the song of _Protonotaria_ but the tone or quality is more wiry and, indeed, very close to that of _Mniotilta_."

_Field marks._--The adult male Cape May warbler should be unmistakable in his brilliant spring plumage, with his black cap, chestnut cheeks, white lesser wing coverts, and bright yellow breast conspicuously streaked with black.

The female lacks the black cap and chestnut cheeks; her breast is pale yellow streaked with pale dusky; and all her colors are duller. Young birds are much like the female, but are still duller in coloration. See descriptions of other plumages. The tail-tilting habit is quite pronounced.

_Fall._--The fall migration starts in August and is prolonged through September, or even into October or a little later. The birds are numerically more abundant in the fall because of the large families of young, but they are less conspicuous while the foliage is still on the trees and while they are clad in dull autumn and immature plumages. Deciduous woods seem to be their favorite haunts at this season. The migration route is a reversal of the spring route, the main flight being between the Mississippi and the Alleghenies.

In this area, the birds are often excessively abundant, as shown by the accounts in the preceding paragraphs under food. They are common in Florida on migration on their way to the Bahamas and West Indies. C. J. Maynard (1896) writes:

"They were very abundant at Key West in November, frequenting the gardens near the houses where they were searching among the tropical trees and shrubs for inesects. The birds were very unsuspicious, often clinging to branches which overhung the sidewalks within a few feet of the passengers. They appeared to prefer the inhabited portion of the Key, for I rarely found them in wooded districts. The majority left the island before the first of December, but a few remained all winter."

_Winter._--Maynard (1896) says: "These birds are also common on all of the northern Bahamas which I have visited, occurring in the thickets about gardens as well as in the dense scrub. I found them abundant on Inagua in February, 1888. Here they were feeding upon the juices of a large tubular flower of a peculiar species of vine, in company with the Bahama Honey Creeper and the Lyre-tailed Hummingbird."

In Cuba, according to Dr. Barbour (1923), "a few arrive from time to time during the autumn, but in February they become really common; they stay until May. They are great flower feeders and haunt aloes and the majagua tree when it is in bloom. Many may be seen about the sisal plantations near Matanzas and in gardens where agaves blossom."

Wetmore and Swales (1931) write: "Though the Cape May warbler is found through the Greater Antilles Hispaniola appears to be the winter metropolis of the species as the birds are found throughout the island often in considerable numbers. In fact their abundance in some localities is almost bewildering to one accustomed to their rarity as migrants in the eastern United States."

DISTRIBUTION

_Range._--Eastern North America and the West Indies.

_Breeding range._--The Cape May warbler breeds =north= to northeastern Alberta (Chipewyan); possibly southwestern Mackenzie (Simpson); northern Saskatchewan (north shore of Lake Athabaska near Fair Point); central Ontario (Moose Factory); and southern Quebec (Lake Abitibi, Lake Edward, and Anticosti Island). =East= to eastern Quebec (Anticosti Island and Grand Grève); New Brunswick (Tabusintac and Saint John); and Nova Scotia (Wolfville and Stewiacke). =South= to Nova Scotia (Stewiacke); southern Maine (Ship Harbor, Mount Desert Island; Hog Island, Muscongus Bay; Pemaquid Point; and Auburn); northern New Hampshire (Lake Umbagog); south-central Vermont (Mount Killington); northern New York (North Elba); southern Ontario (Dorcas Bay and Biscotasing); northern Michigan (Newberry and Camp Cusino); northern Wisconsin (Kelley Brook and Harbster); rarely northeastern Minnesota (Gabro Lake); southwestern Ontario (Lac Seul); and central Alberta (Lesser Slave Lake and Sturgeon Lake). =West= to west-central and northeastern Alberta (Sturgeon Lake and Chipewyan). The Cape May warbler probably breeds in northern Manitoba since it is a regular, though not abundant, migrant in the southern part of the province.

_Winter range._--The winter home of the Cape May warbler is in the West Indies =north= to the Bahamas (Nassau and Watling Island), =east= and =south= to St. Lucia, and =west= to Jamaica and western Cuba (Isle of Pines and Habana). It has also been found on the island of Roatán, Honduras. It was found in Quintana Roo not far from Xcopén on March 13 which is the second record for Mexico; the other is simply "Yucatán."

_Migration._--Late dates of spring departure from the winter home are: Virgin Islands--St. Croix, April 25. Puerto Rico--Mayagüez, April 8. Haiti--Île à Vache, April 30. Cuba--Habana, May 4. Bahamas--Nassau, May 15.

Early dates of spring arrival are: Florida--Key West, March 6. Georgia--Macon, April 7. South Carolina--Chester, April 15. North Carolina--Greensboro, April 13. District of Columbia--Washington, April 19. Pennsylvania--Carlisle, April 30. New York--Geneva, April 30. Massachusetts--Amherst, May 4. Vermont--Clarendon, May 7. Maine--Auburn, May 4. New Brunswick--Scotch Lake, May 8. Nova Scotia--Pictou, May 11. Quebec--Montreal, May 14. Tennessee--Nashville, April 16. Kentucky--Russellville, April 27. Indiana--Bloomington, April 22. Ohio--Oberlin, April 27. Michigan--Ann Arbor, April 27. Ontario--London, May 1; Moose Factory, May 28. Iowa--Davenport, May 2. Wisconsin--Racine, May 2. Minnesota--St. Paul, May 2. South Dakota--Sioux Falls, May 12. North Dakota--Argusville, May 11. Manitoba--Aweme, May 10. Saskatchewan--Indian Head, May 16. Alberta--Medicine Hat, May 17.

Some late dates of spring departure of transients are: Florida--Warrington, May 18. Alabama--Anniston, May 7. Georgia--Round Oak, May 15. South Carolina--Clemson (College), May 17. North Carolina--Arden, May 19. Virginia--Naruna, May 29. District of Columbia, Washington, May 30. Pennsylvania--Doylestown, May 26. New York--Watertown, June 1. Massachusetts--Northampton, June 6. Tennessee--Nashville, May 15. Kentucky--Bowling Green, May 10. Illinois--Chicago, June 3. Indiana--Lafayette, May 31. Ohio--Austinburg June 2. Michigan--Sault Ste. Marie, June 7. Ontario--Ottawa, June 7. Minnesota--Minneapolis, June 1. South Dakota--Sisseton, June 3. North Dakota--Grafton, June 5. Manitoba--Aweme, June 1.

Late dates of fall departure are: Alberta--Camrose, August 26. Saskatchewan--Eastend, August 29. Manitoba--Winnipeg, October 7. North Dakota--Fargo, October 3 (bird banded). Wisconsin--Racine, October 16. Iowa--Iowa City, November 27. Michigan--Detroit, October 16. Ontario--Point Pelee, October 5. Ohio--Cleveland, November 2. Indiana--Waterloo, October 15. Illinois--Rantoul, October 23. Kentucky--Bowling Green, October 15. New Brunswick--Scotch Lake, September 28. Massachusetts--Belmont, November 25. New York--Hewlett, November 15. Pennsylvania--West Chester, October 31. District of Columbia--Washington, November 26. Virginia--Sweet Briar, November 29. North Carolina, Raleigh, November 1. South Carolina--Mount Pleasant, November 3. Georgia--St. Marys, October 31. Florida--Lemon City, November 25.

The Cape May warbler sometimes lingers very late in fall migration. It has been found on Long Island at Hewlett as late as December 4; at Harrisburg, Pa., one was trapped and banded on December 5; it has twice been collected at Washington, D. C., on December 16; one was found at Bethany, W. Va., on December 7; one seen at Brownsville, Tex., on December 22; and reported in December at Key West, Fla.

Early dates of fall arrival are: Manitoba--Winnipeg, August 20. North Dakota--Fargo, September 18. Minnesota--Minneapolis, August 25. Wisconsin--Green Bay, August 1. Illinois--Chicago, August 19. Ontario--Cobalt, August 12. Michigan--Whitefish Point, August 5. Ohio--Toledo, August 14. New Hampshire--Pequaket, August 24. Vermont--Wells River, August 4. Massachusetts--Harvard, August 30. New York--Rhinebeck, August 3. Pennsylvania--Pittsburgh, August 28. District of Columbia--Washington--August 4. Virginia--Charlottesville, September 4. North Carolina--Weaverville, September 15. South Carolina--Charleston, September 13. Georgia--Savannah, September 23. Florida--Sombrero Key, September 17. Bahamas--Cay Lobos, October 20. Cuba--Santiago de las Vegas, September 20. Dominican Republic--Sánchez, October 23. Puerto Rico--Faro de Cabo Rojo, September 17.

_Banding._--The one banding recovery available is especially interesting as it indicates a peculiar migration. A Cape May warbler banded at Elmhurst, Long Island, N. Y., on September 12, 1937, was caught by a cat October 15, 1937 at Cleveland, Tenn.

_Casual records._--In British Columbia one was collected June 17, 1938, at Charlie Lake. In California one was collected at Potholes on the Colorado River, September 23, 1924. A specimen labeled "Arizona" taken before 1876 is in the museum in Paris. The Cape May warbler has been once observed in Bermuda, April 3, 1909.

_Egg dates._--Maine: 2 records, June 6 to 15.

New Brunswick: 68 records, June 10 to 29; 43 records, June 12 to 20; indicating the height of the season.

DENDROICA CAERULESCENS CAERULESCENS (Gmelin)

NORTHERN BLACK-THROATED BLUE WARBLER

PLATES 29, 30

HABITS

This neatly dressed warbler is one of our commonest migrants throughout the eastern half of the United States, but as a breeding bird it is confined mainly to the northernmost States and to extreme southern Canada, almost wholly within the Canadian Zone. Its rather long common name describes this dainty bird.

_Spring._--From its principal winter resort in the West Indies, the black-throated blue warbler migrates through the Bahamas and Florida to the Atlantic States and northward, along the Alleghenies and to the eastward of them, to its northeastern breeding grounds. According to Prof. W. W. Cooke (1904) the earliest arrivals usually strike the Sombrero Key lighthouse in Florida around the middle of April, although there are two or three exceptionally early records in March. As the average dates of arrival in New England and New Brunswick are only about a month later, it would seem that the migration is fairly rapid. But the dates of earliest arrival do not tell the whole story, for Frederick C. Lincoln (1939) observed this species in the mountains of Haiti in the middle of May, showing that there are always many late migrants.

Professor Cooke's records show that this species arrives at Asheville, N. C., a few days earlier than at Raleigh, N. C., suggesting that this is one of the few species that appear in the mountains earlier than on the plains.

There is a northward migration west of the Alleghenies corresponding almost exactly in time with that along the Atlantic slope. Cooke says that "in southern Louisiana and southern Mississippi the black-throated blue warbler is almost unknown." He gives only very few records for any point south of Indiana, and some of these may have come across the Gulf of Mexico. The inference is that the bulk of the birds that migrate northward through the central States may have crossed the lower Alleghenies into these valleys. According to his records, it takes the birds only about 10 days to migrate from Brookville, Ind., to points in Ontario.

On its migration the black-throated blue warbler shows a preference for the lower shrubbery in various kinds of woodlands, but it may also be seen almost anywhere in such suitable cover in our parks and gardens or about human dwellings. Milton B. Trautman (1940) says that, in Ohio, these and the Canada warblers "were close associates in migration and frequented the same habitat niches."

In its summer home this warbler is even more of a woodland bird, frequenting heavy deciduous woods where there is more or less thick undergrowth of mountain-laurel, rhododendron, creeping yew, deciduous bushes, small saplings, or tiny conifers. My most intimate acquaintance with the black-throated blue warbler was made while visiting at Asquam Lake, N. H., with Mr. and Mrs. Richard B. Harding. From their camp the land slopes downward to the shore of the lake and is heavily wooded with tall white oaks, swamp white oaks, red oaks, beeches, maples, paper birches, and other deciduous trees; there are also some white pines and hemlocks scattered through the forest, and a heavy undergrowth of mountain-laurel, striped maple, witch-hazel, and other shrubbery. The black-throated blue warblers and the veeries were the commonest breeding birds in this area.

Gerald Thayer wrote to Dr. Chapman (1907) that about Monadnock, N.H., this is "a bird of the ampler deciduous undergrowth in deep, moist woods--mixed virgin timber or very old second growth. It is peculiarly partial to these woodland conditions, and is common wherever they occur, especially between the altitudes of 1,000 and 2,500 feet. Creeping yew is almost always common in woods where these Warblers breed, and they sometimes, perhaps often, nest in a clump of it." And William Brewster (1938) says that around Umbagog Lake, Maine, "the local population was chiefly concentrated wherever there were extensive patches of yew (_Taxus canadensis_)." I can find no evidence that this warbler is ever common in clear stands of coniferous trees, but is often found in mixed woods where there is a scattering of the evergreens, especially if there are small seedlings of spruce, fir, or hemlock, in which they sometimes build their nests.

_Territory._--In favored regions, where the population is fairly dense, as it often is, the males arrive ahead of the females and establish their breeding and feeding territories, which they often have to defend against intruding males of the same species. John Burroughs (1895) describes such an encounter as follows: "Their battle-cry is a low, peculiar chirp, not very fierce, but bantering and confident. They quickly come to blows, but it is a very fantastic battle, and, as it would seem, indulged in more to satisfy their sense of honor than to hurt each other, for neither party gets the better of the other, and they separate a few paces and sing, and squeak, and challenge each other in a very happy frame of mind. The gauntlet is no sooner thrown down than it is again taken up by one or the other, and in the course of fifteen or twenty minutes they have three or four encounters, separating a little, then provoked to return again like two cocks, till finally they withdrawn beyond hearing of each other,--both, no doubt, claiming the victory."