Part 8

Head winds are as unfavorable to migration as is rain or snow, as they greatly increase the labor of flight and cut down the speed of cross-country travel. If such winds have a particularly high velocity they may force down the weaker travelers, and when this happens over water areas, large numbers of birds are lost. Even strong winds that blow in the direction of aerial travel are unfavorable for the birds, as they interfere with their balance and disarrange their feathers. Moderate tail winds and cross or quartering breezes appear to offer the best conditions for the passage of the migrants.

_Problems of Migration_

=Banding studies=

The study of living birds by the banding method, whereby great numbers of individuals are marked with numbered aluminum leg rings, has come to be recognized as a most accurate means of ornithological research. Since 1920, banding work in North America has been under the direction of the Fish and Wildlife Service in cooperation with the Dominion Wildlife Service of Canada. Every year voluntary cooperators, working under permit, place bands on thousands of birds, game and nongame, large and small, migratory and nonmigratory, each band carrying a serial number and the legend, NOTIFY FISH AND WILDLIFE SERVICE, WASHINGTON, D. C., or on the smaller sizes an abbreviation thereof. When a banded bird is reported from a second locality, a definite fact relative to its movements becomes known, and a study of many cases of this nature develops more and more complete knowledge of the details of migration.

The records of banded birds are also yielding other pertinent information relative to their migrations, such as the exact dates of arrival and departure of individuals, the length of time that different birds pause on their migratory journeys to feed and rest, the relation between weather conditions and the starting times for migration, the rates of travel of individual birds, the degree of regularity with which birds return to the exact summer or winter quarters used in former years, and many other details that could be learned in no other manner. Banding stations that are operated systematically throughout the year, therefore, are supplying much information concerning the movements of migratory birds that heretofore could only be surmised. (See Appendix II, p. 92 for instructions on reporting the recovery of banded birds.)

=Movements of residents=

Typical migration consists of definite movements that are repeated regularly year after year, and it is to these that the term is generally restricted. It is desirable, however, if only for purposes of comparison, that some account be taken of the movements of some other birds, which, while not typical, do possess some of the characteristics of true migration. Data on this subject are being collected through bird banding.

There are several species that are customarily grouped under the heading "permanent residents," the term implying that these birds do not travel but remain throughout the year in one locality. Among these are the cardinal, the tufted titmouse, the wrentit, the Carolina wren, the house finch, the bobwhite, the California quail, and the ruffed grouse. Each species may be present constantly throughout the year, although in the northern part of the range there is probably a slight withdrawal of the breeding birds in winter. The individuals to be seen at that season, therefore, may not always be the same as those observed during the summer. It is certain, however, that these species do not regularly perform extensive journeys.

While the blue jay is disposed to be secretive, it is such a showy and noisy bird that it is not likely to escape notice. In the vicinity of Washington, D. C., as in many other places, it is present the year round, but at the end of September or early in October when the weather is becoming cooler, troops of jays are sometimes seen working southward through the trees. A corresponding northward movement occurs again in May. This is unquestionably a migration to and from some winter range, but its extent or significance is not now known. Some light is being shed on the matter, however, through the records of banded birds, and these eventually will fill in a more perfect picture of the movements of this species. One jay, banded on September 14, 1923, at Waukegan, Ill., was killed at Peruque, Mo., on November 15 of the same year; another, banded at Winnetka, Ill., on June 16, 1925, was retaken at Sulphur Rock, Ark., the following December 10; a third, banded on May 6, 1925, at Whitten, Iowa, was recaptured at Decatur, Ark., on January 22, 1926. These three birds unquestionably had made a flight that had every appearance of being a true migration to winter quarters in Missouri and Arkansas.

The black-capped chickadee is apparently resident in many places, but occasionally in winter it invades the range of the southern Carolina chickadee, and in northern Canada it is regularly a migrant.

In the coastal plain between Washington, D. C., and the Atlantic Ocean, the white-breasted nuthatch is usually absent during the summer, nesting at that season in the higher, or piedmont, country. Late in fall, however, it appears in fair abundance in the wooded bottoms, remaining at the lower levels until the following March or April.

Some birds, including the screech owl, bobwhite, Carolina wren, and mockingbird, seem to be actually sedentary, but even these are sometimes given to post-breeding wanderings. Ordinarily bobwhites that are marked with numbered bands are seldom retaken far from the area where banded, but sometimes they will travel 10 miles or more. A screech owl banded at Glenwood, Minn., in March, was recovered the following December at Emmetsburg, Iowa, 180 miles south. Such flights, however, are probably more in the nature of a search for new feeding areas, or to escape from a winged enemy, than a true migratory journey.

=Migration of the white-throated sparrow=

The white-throated sparrow, one of the most abundant members of its family, breeds from northern Mackenzie and the southern part of the Ungava Peninsula south to southern Montana, northern Pennsylvania, and Massachusetts. The winter range extends from the southern part of the breeding range south to the Gulf coast and northeastern Mexico. It is therefore a common migrant in many sections. Since it is a ground-feeding bird and is readily attracted to the vicinity of dwellings, it has been banded in large numbers, the total to November 14, 1949, being nearly 283,500. It would be expected that these would yield a comparable number of return records that would furnish basic data relative to the migrations of the species. Such, however, is not the case. Banded white-throated sparrows are rarely recaptured at stations between the breeding and wintering grounds. Operators of stations in the winter area, as Thomasville, Ga., and Summerville, S. C., have obtained return records showing that these birds do come back to the exact winter quarters occupied in previous seasons. The fact that they do not again visit banding stations on their migration routes indicates some unusual aspects of their travels, which it is hoped will eventually be discovered by banding studies. Problems of this type constitute definite challenges to the student of bird migration.

=Migration of the yellow-billed loon=

The semiannual movements of the yellow-billed loon present an unusual problem in migration. It breeds along the Arctic coast, probably from Cape Prince of Wales eastward to Franklin Bay, and also in the interior of northern Canada south to Clinton-Colden, Aylmer, and Artillery Lakes, where it is rather common. It has been reported as already present by May 25 at the mouth of the Liard River, in southwestern Mackenzie. This coincides with the time that first arrivals are noted fully 700 miles north, at Point Barrow, Alaska. The problem has been to ascertain the route used by these birds to their principal nesting grounds in the interior.

For a long time it was believed that this big diver did not winter in large numbers anywhere on the Pacific coast, and it had been supposed that the spring route extended 2,000 miles northeastward from a wintering ground somewhere in eastern Asia to Bering Strait, then 500 miles still northeast to round Point Barrow, then 500 miles east to the coast of Mackenzie, and finally 700 miles south--in spring--to the region near the eastern end of Great Slave Lake.

The yellow-billed loon is a powerful flier, and it is probable that this suggested route is correct for those birds that breed in the northern coastal regions. A reasonable doubt may be entertained, however, whether the breeding birds of Great Slave Lake and contiguous areas reach their breeding grounds by the 700-mile flight south from the Arctic coast. Within recent years it has been found that these birds are fairly common in the maze of channels and islands off the coast of southeastern Alaska as late as the last of October and in February. Possibly they are present there during the period from November through January also, or they may at that time move farther off shore and so escape detection. If this region is an important wintering ground, as seems probable, then it is likely that the breeding birds of the interior reach their nesting grounds by a flight eastward across the mountains, a trip that is well within their flying ability, rather than by a circuitous route around the northern coast. The air-line distance from southeastern Alaska to the mouth of the Liard River is in fact less than the distance to that point from the mouth of the Mackenzie.

Differing routes to various parts of a large breeding or wintering ground, and used by large groups of individuals of other species, are not unknown. For example, the redhead duck is one of the common breeding ducks of the Bear River marshes of Utah, where a great many have been banded each summer. The recovery records of banded redheads show that while many travel westward to California, others start their fall migration in the opposite direction and, flying eastward across the Rocky Mountains, either turn southeast across the plains to the Gulf of Mexico, or deliberately proceed in a northeasterly direction to join the flocks of this species moving toward the Atlantic coast from the prairie regions of southern Canada.

_Conclusions_

The migration of birds as it is known today had its beginning in times so remote that its origins have been entirely obscured, and it can be interpreted now only in terms of present conditions. The causes underlying migration are exceedingly complex. The mystery that formerly cloaked the periodic travels of birds, however, has been largely dispelled through the fairly complete information that is now available concerning the extent and times of the seasonal journeys of most of the species. Many gaps, however, still remain in our knowledge of the subject. Much has been learned, and present knowledge is being placed on record, but it must be left to future study to clear away many of the uncertainties that continue to make bird migration one of the most fascinating subjects in the science of ornithology.

Each kind of bird seems to have its own reaction to its environment, so that the character of movement differs widely in the various species, and seldom do any two present the same picture. In fact, bird migration has been described as a phase of geographic distribution wherein there is a more or less regular seasonal shifting of the avian population caused by the same factors that determine the ranges of the sedentary species. If this view is correct, then it must be recognized that the far-reaching works of man in altering the natural condition of the earth's surface can so change the environment necessary for the well-being of the birds as to bring about changes in their yearly travels. The nature and extent of the changes wrought by man on the North American Continent are easily apparent. Forests have been extensively cut away and their places have been taken by second growth or cultivated land, and wide stretches of prairie and plain have been broken up, irrigated, and devoted to agriculture. These great changes are exerting a profound effect upon the native bird populations, and the various species may be either benefited or adversely affected thereby.

The Federal Government has recognized its responsibility to the migratory birds under changing conditions brought about by man, and by enabling acts for carrying out treaty obligations, it is now giving most species legal protection under regulations administered by the Fish and Wildlife Service. Much is being done by legislation for the welfare of the birds. The effectiveness of these conservation laws, however, is increased in the same measure that the people of the country become acquainted with the facts in the life histories of the migrants and interest themselves personally in the well-being of the various species. Long before the white man came to America the birds had established their seasonal lanes of migration throughout the Western Hemisphere. The economic, inspirational, and esthetic values of these migratory species dictate that they be permitted to continue their long-accustomed and still-mysterious habits of migration from clime to clime.

Appendix I--_List of Birds Mentioned in the Text_

Common name Scientific name

American egret _Casmerodius albus egretta_ Arctic tern _Sterna paradisaea_ Atlantic brant _Branta bernicla hrota_ Atlantic golden plover _Pluvialis dominica dominica_ Bank swallow _Riparia riparia_ Barn swallow _Hirundo rustica erythrogaster_ Bartramian sandpiper or _Bartramia longicauda_ upland plover Belted kingfisher _Ceryle alcyon_ Black-and-white warbler _Mniotilta varia_ Black-billed cuckoo _Coccyzus erythropthalmus_ Black brant _Branta bernicla nigricans_ Black-capped chickadee _Parus atricapillus atricapillus_ Black-crowned night heron _Nycticorax nycticorax hoactli_ Black duck _Anas rubripes_ Black-headed grosbeak _Pheucticus melanocephalus_ Blackpolled warbler _Dendroica striata_ Black-throated blue warbler _Dendroica caerulescens_ Bluebird _Sialia sialis_ Blue goose _Chen caerulescens_ Blue jay _Cyanocitta cristata_ Bluethroat _Cyanosylvia suecica_ Blue-winged teal _Anas discors_ Bobolink _Dolichonyx orizivorus_ Bobwhite _Colinus virginianus_ Bohemian [greater] waxwing _Bombycilla garrulus pallidiceps_ Brewer's blackbird _Euphagus cyanocephalus_ Broad-winged hawk _Bueto platypterus_ Bronzed grackle _Quiscalus guiscula versicolor_ Brown [tree] creeper _Certhia familiaris_ Cackling [Canada] goose _Branta canadensis minima_ California quail _Lophortyx californica_ Canada goose _Branta canadensis_ Canvasback _Aythya valisineria_ Cape May warbler _Dendroica tigrina_ Cardinal _Richmondena cardinalis_ Carolina chickadee _Parus carolinensis_ Carolina wren _Thryothorus ludovicianus_ Chimney swift _Chaetura pelagica_ Chipping sparrow _Spizella passerina_ Chuck-wills-widow _Caprimulgus carolinensis_ Clark's nutcracker _Nucifraga columbiana_ Cliff swallow _Petrochelidon pyrrhonota_ Common tern _Sterna hirundo_ Cooper's hawk _Accipiter cooperi_ Coot [American] _Fulica americana_ Cowbird _Molothrus ater_ Crossbill _Loxia curvirostra_ Crow _Corvus brachyrhynchos_ Duck hawk [peregrine falcon] _Falco peregrinus_ Eastern fox sparrow _Passerella iliaca iliaca_ Eider _Somateria mollissima_ Emperor goose _Philacte canagica_ Evening grosbeak _Hesperiphona vespertina_ European blackbird _Turdus merula merula_ Field sparrow _Spizella pusilla_ Forster's tern _Sterna forsteri_ Frigate [man-o'-war] bird _Fregata magnificens_ Golden-crowned kinglet _Regulus satrapa_ Golden plover _Pluvialis apricaria_ Golden-winged warbler _Vermivora chrysoptera_ Goshawk _Accipiter gentilis_ Grackle _Quiscalus quiscula_ Gray-cheeked thrush _Hylocichla minima_ Greenland wheatear _Oenanthe oenanthe leucorhoa_ Harris's sparrow _Zonotrichia querula_ Hermit thrush _Hylocichla guttata_ Herring gull _Larus argentatus_ Horned lark _Eremophila alpestris_ Horned owl _Bubo virginianus_ House finch _Carpodacus mexicanus_ Ipswich sparrow _Passerculus princeps_ Jacksnipe [see Wilson's snipe] _Capella gallinago delicata_ Junco _Junco hyemalis_ Kentucky warbler _Oporonis formosus_ Kingbird _Tyrannus tyrannus_ Knot _Calidris canutus_ Kodiak fox sparrow _Passerella iliaca hyperborea_ Lapland longspur _Calcarius lapponicus_ Lapwing _Vanellus vanellus_ Lesser yellowlegs _Totanus flavipes_ Little blue heron _Florida caerulea_ Loggerhead shrike _Lanius ludovicianus_ Long-billed marsh wren _Telmatodytes palustris_ Mallard _Anas platyrhynchos_ Maryland yellowthroat _Geothlypis trichas trichas_ Meadowlark _Sturnella magna_ Migratory quail _Coturnix coturnix_ Mockingbird _Mimus polyglottos_ Mourning dove _Zenaidura macroura_ Myrtle warbler _Dendroica coronata_ Nighthawk _Chordeilies minor_ Noddy tern _Amous stolidus_ Northern phalarope _Lobipes lobatus_ Northern robin _Turdus migratorius migratorius_ Orchard oriole _Icterus spurius_ Ovenbird _Seiurus aurocapillus_ Pacific [American] golden _Pluvialis dominica fulva_ plover Parasitic jaeger _Stercorarius parasiticus_ Peregrine falcon [duck hawk] _Falco peregrinus_ Pine Grosbeak _Pinicola enucleator_ Pine warbler _Dendroica pinus_ Pintail _Anas acuta tzitzihoa_ Pipit _Anthus spinoletta_ Poor-will _Phalaenoptilus nuttallii_ Purple finch _Carpodacus purpureus_ Purple martin _Progne subis_ Purple sandpiper _Erolia maritima_ Raven _Corvus corax_ Red-eyed vireo _Vireo olivaceus_ Redhead _Aythya americana_ Red-legged kittiwake _Rissa brevirostris_ Redpoll _Acanthis flammea_ Redstart _Setophaga ruticilla_ Red-tailed hawk _Buteo jamaicensis_ Red-winged blackbird _Agelaius phoeniceus_ Robin _Turdus migratorius_ Rock wren _Salpinctes obsoletus_ Rose-breasted grosbeak _Pheucticus ludovicianus_ Ross's goose _Chen rossi_ Ross's gull _Rhodostethia rosea_ Rosy finch _Leucosticte tephrocotis_ Rough-legged hawk _Buteo lagopus_ Ruby-throated hummingbird _Archilochus colubris_ Ruffed grouse _Bonasa umbellus_ Rusty blackbird _Euphagus carolinus_ Sanderling _Crocethia alba_ Scarlet tanager _Piranga olivacea_ Scaup _Aythya marila_ Screech owl _Otus asio_ Sharp-shinned hawk _Accipiter striatus_ Shumagin fox sparrow _Passerella iliaca unalaschensis_ Slate-colored junco _Junco hyemalis_ Snow bunting _Plectrophenax nivalis_ Snow goose _Chen hyperborea_ Snowy heron _Leucophoyx thula_ Snowy owl _Nyctea scandiaca_ Song sparrow _Melospiza melodia_ Sooty fox sparrow _Passerella iliaca fuliginosa_ Sooty tern _Sterna fuscata_ Sora or Carolina rail _Porzana Carolina_ Southern robin _Turdus migratorius achrusterus_ Starling _Sturnus vulgaris_ Swainson's hawk _Buteo swainsoni_ Swamp sparrow _Melospiza georgiana_ Townsend's fox sparrow _Passerella iliaca townsendi_ Tree sparrow _Spizella arborea_ Tufted titmouse _Parus bicolor_ Turkey vulture _Cathartes aura_ Turnstone _Arenaria interpres_ Upland plover [Bartramian _Bartramia longicauda_ sandpiper] Valdez fox sparrow _Passerella iliaca sinuosa_ Vesper sparrow _Pooecetes gramineus_ Western palm warbler _Dendroica palmarum palmarum_ Western tanager _Piranga ludoviciana_ Western wood pewee _Contopus richardsonii_ White-breasted nuthatch _Sitta carolinensis_ White-throated sparrow _Zonotrichia albicollis_ White-winged scoter _Melanitta fusca_ Widgeon _Mareca americana_ Williamson's sapsucker _Sphyrapicus thyroideus_ Wilson's [common] snipe _Capella gallinago delicata_ Winter wren _Troglodytes troglodytes_ Woodcock _Scolopax rusticola_ Wood thrush _Hylocichla mustelina_ Worm-eating warbler _Helmitheros vermivorus_ Wrentit _Chamaea fasciata_ Yakutat fox sparrow _Passerella iliaca annectens_ Yellow-billed cuckoo _Coccyzus americanus_ Yellow-billed loon _Gavia adamsii_ Yellow-headed blackbird _Xanthocephalus xanthocephalus_ Yellow palm warbler _Dendroica palmarum hypochrysea_ Yellow warbler _Dendroica petechia_

Appendix II--_Bird Banding_

Frequent reference has been made in this bulletin to bird banding as a means for obtaining information on the migrations and life histories of birds. Since 1920 this work in North America has been under the direction of the Fish and Wildlife Service in cooperation with the Dominion Wildlife Service of Canada. Each year birds to the number of a quarter of a million or more may be marked with numbered bands.

As anyone interested in birds, either game or nongame, may have a marked individual come into his hands, there are several pertinent details that should be remembered if the recovery record is to have maximum value in advancing the science of ornithology.