Chapter VII: The Relation of the Territory to Migration (2)

Now if the fundamental assumption of the doctrine of the struggle for existence be true, the gregarious instinct will not be quite alike in all the members of different broods, nor even in each member of the same brood; that is, variation will occur in all possible directions. And we shall not, I think, exceed the limits of probability if we assume that different individuals vary in the persistency with which they strive to attain their unknown end, and in the direction in which they travel in pursuit of it. So that in each generation they will fall into three classes: (1) those which are inert, (2) those which wander along the line of expansion, (3) those which wander in other directions. If then the struggle for life at this particular juncture in the evolution of the breeding range is a struggle for the means of subsistence, the members of these three classes will not be in a like satisfactory position so far as the competition for food is concerned. Those in the first class--_i.e._, those in which the activity feelings are weak--will neither gain the benefits which arise from mutual help, nor will they have much prospect of enduring through the season of scarcity. Those in the third class will, it is true, derive some assistance one from another, and so be in a better position to discover what food may be available; but inasmuch as they will remain in regions where the climate alternates and the supply of food is liable to fall below the minimum required, the chances are that a high percentage will fail in the struggle for existence. We come now to those in the second class, and it is upon them that I wish more particularly to focus attention. The initial movement in their case will be in the direction from which outward expansion has all along taken place. Within a comparatively short distance they will reach districts where the species is plentiful, and here, associating with others that have some traditional experience, they will be guided by them and will find themselves in regions where food is plentiful. Hence in each generation those will survive that, owing to some congenital variation of their instinct, seek satisfaction for their impulse in a direction which brings them under the influence of tradition. And though at first but slight and not in themselves of survival value, such variations, since they coincide with modifications of behaviour due to acquired experience, will be preserved and in the process of time so accumulated as to be capable of determining the direction and extent of the movement.

But the young Cuckoo deserts this country many weeks after its parents, and there is no reason to suppose that it lives in society when eventually its destination is reached; and the young Falcon passes to the south, and is certainly not gregarious--how then can we explain their behaviour in terms of something which they show no signs of possessing? I do not wish to make light of a difficulty which admittedly, at first sight, is a grave objection to the view that the gregarious instinct has been operative in the manner here claimed for it. It must, however, be borne in mind that this instinct, though originally developed to serve the purpose of mutual protection, supplies the material upon which evolution works when the extension of the breeding range creates a situation requiring readjustment on the part of the organism to new conditions of life; and that those variations which can be so modified as to be in useful relation to the new environmental circumstances are seized upon by natural selection and, being transmitted, form the foundation of a specific inherited response, no longer dependent upon, though operating in close relation with the primitive response whence originally it sprang. Thus the primordial instinct becomes so organised as to serve a secondary purpose, that of rendering secure a means of access to a certain food supply. In the course of evolution species were bound to arise which, owing to some peculiar conditions, derived greater advantage from living solitary than from living in society. Does it then follow, because such species manifest no inclination to live in society, that the instinct never has played any part in their lives? Or because the primary purpose has lapsed, does it follow that the secondary no longer exists?

Let me recapitulate the principal considerations which I have discussed in this chapter.

Though I have been advancing a theory, and though I have taken much for granted, yet it will, I think, be admitted that both the theory and what has been taken for granted rest on observational grounds. As our starting-point we have a bird whose inherited nature alternates according to the season, and in whose nature we can distinguish two contra-phases--the one to live in society, the other to live solitary. While both have their part to play in furthering the life of the individual, for biological interpretation there is only one end, the prospective value of which is the continuance of the race. We may say that the latter phase is the more important of the two because it is directly concerned with reproduction. But we shall make a great mistake if we attach peculiar importance to one phase, or to one mode of behaviour within that phase, or to one action within that mode of behaviour; for if there is one thing certain it is that the whole is an inter-related whole in which each part depends for its success upon that which precedes it.

In that phase in which the territory is the central feature of the situation, the struggle for existence is in operation in its acutest form; all the congenital and acquired capacities of the bird--pugnacity, song, capacity to utilise in later phases the experience gained in prior phases, all these are organised to subserve an end--a proximate end--which in its simplest terms may be described as "isolation." Isolation is then the first step in the process of reproduction, and any individual that fails to make it good, fails to procreate its kind. But isolation implies separation, and the degree of separation varies in different species, from the few square feet of cliff required by the Guillemot to the few square miles of barren moor over which the Peregrine exercises dominion. One species must occupy sufficient ground to enable it to secure food for its young; another requires sufficient, but no more, upon which to deposit its egg; and a third must secure a position for its nest within the community. Hence it follows that the degree of separation varies with the conditions of existence. Since, however, the conditions in the external world are constantly changing according to the relative abundance or scarcity of enemies, the rise or fall of rivals, the physical changes in the earth's surface, and the alterations of climate, it is clear that isolation can only be obtained with difficulty, and that the competition for it must be severe. Some individuals therefore fail to breed, whilst others, perhaps because their impulse is stronger, persevere and seek stations elsewhere. What are their prospects of finding them? By extending the field of their activities, they will wander into districts remote from the scene of competition, districts where not only food is plentiful but where enemies and rivals are scarce; and to these pioneers, if to any, success in reproduction will most certainly be assured. But not only is it they who will benefit; their offspring also, when the time comes for them to take their part in the maintenance of the race, will share in the success of their parents, for even though they may not escape competition from individuals of closely related forms, they will meet with but little from those of their own kind. Now species which live throughout the year in the vicinity of their territory are comparatively few, the majority are obliged to wander in search of food so soon as reproduction is ended, and their behaviour is determined not only by its abundance or scarcity, but also by the powerful gregarious impulse which waxes in proportion as the instincts connected with reproduction wane. If, then, when the sexual instinct again becomes predominant, the experience of the former season nowise affects their movements, little or no progress will be made in the expansion of the range. But just as a certain entrance into the bush and pathway through it, when once made use of in the process of building, becomes so firmly established as to form the sole highway to and from the nest, so likewise, when the impulse to seek isolation repeats itself, the bird is constrained to seek the neighbourhood wherein it had experienced the enjoyment of breeding or of birth. Thus the little that is added one year becomes the basis for further additions in the next, and new centres of distribution are continually being formed from which expansion proceeds anew.

Now as the range gradually extends into regions where the climate alternates and food at certain seasons is consequently scarce, the distance between the customary area of association and that of reproduction must perforce widen. The question then arises: How will the young that have no experience find their way to regions wherein they can endure? The forces which may have been organised to subserve the end in view are three: (1) Acquired experience, (2) tradition, (3) the gregarious instinct. The pioneer that carries the range a little further forward starts from a base where it has associated with companions and found food plentiful; and when the impulse to live in society again asserts itself, it not only repeats its former experience but hands on the habit thus acquired to those of the next generation that happen to accompany it. Granting, however, that by successive increments in the distance traversed, traditional guidance may in time accomplish much, it cannot account for all the known facts, it cannot at any rate explain the fact that in some cases the inexperienced offspring finds its way to the food area without guidance. Something, therefore, _is_ inherited. And my suggestion is this: That the gregarious instinct, the ancient origin of which we can infer from its manifestation in so many and diverse forms of life, supplies the material upon which evolution works; that variations of the initial impulse, at first slight and not in themselves of selection value, in so far as they coincide in direction with modifications of procedure due to experience or tradition, are preserved; and that, in the process of time, they are so accumulated as to form a specific congenital endowment determining a definite mode of behaviour.

FOOTNOTES:

[1] June 1915, R. M. Barrington.

[2] _Dictionary of Birds_, p. 556.

[3] _Social Psychology._

[4] _Manual of Psychology._

[5] _Ibis_, April 1918.

[6] _Zoologist_, 1912, p. 327.

INDEX

Acquired experience, 300

Adjustments, transitory, of distribution, 275

Alarm notes, 119

Arrival, advantages and disadvantages of late, 33-44

Assemblies in winter, 262, 263

Assembly grounds, 173

Attainment of reproduction, 171

Barrington, R. M., on the sex of migrants, 25

Battle between two male Cuckoos, 82

---- between two Moor-Hens, 86, 92, 93, 94

---- ---- Pied Wagtails, 86

---- ---- Raven and Buzzard, 217

---- ---- Raven and Peregrine, 216
law of, 13,19

Behaviour routine, 262

---- sexual, 3

Bickerings, 96

Birthplace, return to, 43, 50

Blackbird, 87, 182, 222, 244

Blackcap, 81, 156, 224, 230

Black Grouse, 63

Black-tailed Godwit, 53

Boundaries, 1, 5

---- conflicts for retention of, 7, 62

---- disputes as to, 1

Brambling, 124

Breeding ground, search for appropriate, 270, 271

---- range, extension of, 291-92

---- site, acquirement of, 3

---- stations, evolution of, 15-19

---- ---- repeatedly visited long before nesting-time, 64

---- territory, 2, 3, 7

---- ---- evolution of, 18

---- ---- foundation of, 7

---- ---- innate capacity to return to former, 279-81

Bridled Guillemot, 64

Brooding, 180

---- impulse, 191

Bunting, Cirl, 28, 140

---- Corn, 28

---- Reed, 28, 68, 69, 85, 104, 132, 158, 160, 244

---- Yellow, 28, 30, 47, 64, 140, 159, 162, 183, 187, 188, 189,
235, 236, 286

Buzzard, 217

Capacity, innate, to return to former breeding territory, 279-81

Carrion Crow, 226

Chaffinch, 28, 31, 32, 33, 45, 87, 103, 156, 159, 235, 236, 244

---- Donegal, 160

Change of breeding quarters owing to unsuitableness, 50

Chiffchaff, 49, 51, 80, 139, 140, 221, 224, 244

Cirl Bunting, 28, 140

Clarke, W. Eagle, _Studies in Bird Migration_, 24

Cleanliness of nest, 180

Cliff-breeding species, 63

Climatic changes, alteration of routine, due to, 284

---- changes, food dependent on, 283

---- conditions, influence of, 20

Communities, 202

---- birds after breeding-season remain in, 265-67

Competition, female, for males, 13

Complexity of strife, 84-85

Conflicts between males during the mating period, 74, 86

---- between males during the nesting period, 87

---- for areas, 10, 11, 13, 62

---- of Ruff, 54

---- sexual, 10

Congenital disposition, 135

Contests between males for possession of females, 80

Coot, 61

Corn-Bunting, 28

Corncrake, 39

Crow, Carrion, 226, 227

Crow, Hooded, 202

Cuckoo, 52, 82, 144, 296

---- restricted breeding area, 52

Curlew, 119, 138, 140, 250, 262, 263, 265, 273

Danger warnings, 269

Darwin, C., _Descent of Man_, 35

---- on the arrival of males before females, 35

Defence of territory, 6

Development, sexual, 6

Disposition, congenital, 135

---- functioning of, 74

---- inherited, 5

---- to defend the territory, 73-118

---- to mate, 27

---- to remain in a particular place in a particular environment, 6

---- to secure a territory, 6, 20-72

Distribution, adjustment of, 275

Dove, Turtle, 126, 232

Dunlin, 250

Emotional behaviour, 53, 82, 114

---- manifestation, 90, 283

---- response, 26

Enemies, 282

Energy, waste of, 219

Environment, 6

---- and food, 56

---- changes of, 283

---- external, conditions in, 279, 282

Equipment, hereditary, 6

Evolution of breeding stations or territory, 15, 19

---- of the territory, 176

---- of the voice, 163

Existence, struggle for, 294

Experience, acquired, 300

Experiments, removal of nests for, 181, 185, 190, 213, 214

Exposure, its effect on nestlings, 180

External environment, conditions in, 279, 282

Falcon, 48, 71

Feeding grounds, neutral, 125 in communities, 70

Females, fighting amongst, 109-118

---- sexual impulse of, 13

Fieldfare, 124

Fighting instinct, 79, 82

Flight, emotional behaviour of Godwit during, 53

Flocks, in winter, birds collect together in, 262

Flycatcher, 244

Food, procuring of, 5

---- abundance, or scarcity of, its relation to prosperity of young,
15, 16

---- its bearing, on the movement of flocks, 262

---- rearing of young dependent on rapid and regular, 179, 195

---- supply, proximity to, necessary for rearing young, 179, 195

Fortuitous mating, 174

Fowler, Ward, on the value of communities, Rooks, 202

Fulmar, 121, 247

Functional activity, 259

---- instinct of Reeve, 173

Functioning of the disposition, 275

---- of the primary dispositions, 100

Garden Warbler, 223, 225, 230

Gätke, H., _Birds of Heligoland_, 24

---- on the absence of song in birds on Heligoland, 124

---- on the early arrival of Guillemots on Heligoland, 64

Godwit, emotional behaviour of, during flight, 53

---- Black-tailed, 53

Grasshopper Warbler, 39, 131, 139, 153, 155, 187, 244

Greenfinch, 28, 33, 140, 235, 236

Gregarious instinct, 20, 61, 141, 265-66, 269, 276, 289, 290, 291,
296, 300

Grouse, Black, 63

Guillemot, Bridled, 64

---- Common, 63, 64, 121, 192, 195, 206, 211, 247

---- Ringed, 64

Gull, Common, 119

---- Herring, 210, 278

Habit formation, law of, 8, 62, 65, 66, 67, 205

Hawfinch, 28

Headquarters, 176, 206, 207, 274

---- restricted, 8, 9, 30, 50, 58, 64, 127

Hedge-Sparrow, 213, 221, 244

Hereditary equipment, 6

Herring-Gull, 210, 278

Hooded-Crow, 202

Hostility and territory, relationship between, 242

House-Sparrow, 218

Imitation, vocal, powers of, 156, 157, 161

Impulse, internal, 279

---- to brood, 191

Inherited disposition, 5

Instinct, fighting, 79-82

---- gregarious, 20, 61, 141, 265, 266, 269, 276, 289, 290, 291, 296,
300

---- migratory, 37

---- of song related to establishment of territory, 125

---- sexual, reawakening of, 4, 18

Instinctive response, 180

Instincts susceptible to stimulation, 259

Internal impulse, 279

Internal stimulation, 62, 123

Interpretation of battles, 75

Intolerance of other birds, 218, 219

Intrusion resented, 274

Isolation, impulse to seek, 288

---- of male, 12, 62, 65, 73, 81

---- of male during breeding season, 267, 272, 273, 275, 281

Jay, 87, 156, 283

Kestrel, 228

Kittiwake, 116, 200, 247

Lapwing, 58, 59, 61, 62, 64, 84, 103, 104, 126, 189, 190, 220, 251, 284

Lapwing, life-history of, 58-61

Late arrival, advantages and disadvantages of, 33-44

Law of battle, 74, 75, 86

Lesser Whitethroat, 230, 244

Linnet, 156

M'Dougall, Dr, _Social Psychology_, 77

Magpie, 219, 283

Males arrive before advent of females, 24

Marsh-Warbler, 39, 40, 52, 81, 132, 140, 153, 155, 156, 165, 225

Martin, 201, 218

Mating, difficulties of, 172

---- fortuitous, 174

Maximum number supportable in a given locality, 49

Meadow-Pipit, 188

Meeting places for antics, 54, 63

Mental Image, 77

Merlin, 227

Migration, 3-4

---- distance no criterion, 279

---- its relation to territory, 259

Migration, origin of, 260, 277

---- phenomenon of, 277

Migratory instinct, 37

---- species more highly specialised than resident species, 56

Missel-Thrush, 21

Mobility of the land and stability of the water, 260

Moor-hen, 61, 85, 103, 218, 250, 251

Morgan, Professor Lloyd, on instinctive behaviour, 74

---- on emotional behaviour, 114

Nest, cleaning of, 180

---- construction of, 3

Nests, removal of, for experiments, 181, 185, 190, 213, 214

Neutral feeding grounds, 62, 125

---- ground, 98

Newton, E., on the arrival at breeding stations of males before female,
24, 35

Nightingale, 39, 156

Notes of alarm, 119

---- of anger, 119

---- of recognition, 139

---- of warning, 119, 139, 141, 145, 151, 153

Offspring, rearing of, 3, 4

Organic change, sexual, 92, 123

---- changes, 65

---- condition of Reeve, 173

Owl, Wood, 156

Paired for life, 55-56

Parental instinctive response, failure of, 185

Partridge, 87, 218

Persecution, Carrion Crow and Magpie, 226

Persecution, Carrion Crow and Rook, 227

---- House Sparrow and Martin, 218

---- Lapwing and Snipe, 220

---- Raven and Buzzard, 217

---- ---- and Peregrine, 216

---- Starling and Woodpecker, 218, 237

Persistency to remain in territory, 68

Pied-Wagtail, 86, 155

Pigeon, Wood, 219

Pipit, Meadow, 188

---- Tree, 51, 188, 189, 222, 244, 278

Polyandrous females, 144

Predatory species, 268

Promiscuous pairing of Ruffs, 172

Proximity to food-supply necessary for rearing young, 179, 195

_Psychology, Manual of_, 1

Puffin, 63, 116, 200

Pugnacious instinct, 87-109

Pugnacity, 11, 62

---- of females to obtain mates, 109-118

---- of males, prior to mating-season, 77-81

---- of Moor-Hen, 218

Racial preparation, 41, 43, 46, 67, 205, 206, 266

Rail, Water, 218

Raven, 48, 202, 216

Razor-bill, 63, 64, 200, 247

Readjustment of territory, 146

Rearing of offspring, 3, 4

Red-backed Shrike, 39, 50, 51, 156

Redbreast, 47

Redshank, 139

Redwing, 124

Redstart, 230, 244

Reed-Bunting, 28, 68, 69, 85, 104, 132, 156, 158, 160, 244, 246, 273

Reed-Warbler, 49, 51, 68, 81, 132, 140, 152, 153, 211, 225

Reeve, 171

Relation of song to the territory, 119-68

---- of territory to migration, 259

---- of territory to the system of reproduction, 169-214

Relationship to a territory, 169

Reproduction, 14, 15

---- and territory, 169-214

---- attainment of, 2, 6, 37

---- goal of, 6

Ringed Guillemot, 64

Robbery of territory, 104-107

Rock-formation, suitability for Guillemots nesting on, 196

Rook, 202, 227

Routine behaviour, 262

Ruff, 54, 63, 172

---- meeting places for conflicts, 54

Ruffs, promiscuous pairing of, 172

Savi's Warbler, 139

Sedge-Warbler, 25, 44, 152, 226, 244

Selous, E., on the life-history of Ruffs and Reeves, 172

---- on meeting places for conflicts and antics, 54

---- on the meeting places of Black Grouse, 63

Service, Robert, on flocks of unmated Sedge-Warblers, 44, 45

Sexual behaviour, 3

---- conflicts, 10

---- development, 6

---- function, discharge of, 2, 3, 26

---- impulse of females, 13

Sexual instinct in the migratory male, 26

---- of Reeve, 173

---- ---- reawakening of, 4, 18

---- life of birds, 1

---- maturity, males arrive at, before females, 36

---- organic change, 92, 123

---- selection, 166

Shag, 121

Shrike, Red-backed, 39, 50, 51, 156

Skylark, 188, 236, 244

Snipe, 153, 156, 219, 220

Sociability when not paired, 125, 126

Song, as an aid in searching for a mate, 12

---- its influence on mating, 167

---- origin of, 138

---- relation to reproduction, 123

---- relation to territory, 119-168

---- volume of, influenced by age, seasonal sexual development,
or isolation, 166

Song-Thrush, 222, 244

Sparrow, House, 218

Sparrow-Hawk, 269

Spring, at approach of, birds lose their shyness, 138

Stability of the water and mobility of the land, 260

Starling, 217, 218, 237, 251

Stimulation, internal, 62, 123

---- question of, 284

Stonechat, 87 187, 188, 189, 222, 233, 234

Stout, Dr, _Manual of Psychology_, 1, 77

Struggle for existence, 294

Susceptibility to position, 96

Swallow, 21, 156, 278

Territory, 1, 5

---- adjustment of, 10

Territory and reproduction, 169-214

---- breeding, 2, 3, 7

---- dates of acquisition of, 33

---- defence of, 6

---- desertion of, after rearing young, 276

---- disposition to defend, 73-118

---- disposition to secure, 6, 20-72

---- establishment of, 74, 285

---- evolution of, 176

---- failure to secure, 286

---- fights for, 10, 11, 13, 62

---- ownership of, 189

---- possession of, a stimulus to song, 136

---- its relation to migration, 259

---- its relation to reproduction, 169-214

---- readjustment of, 147

---- restriction of, advantageous for mating, 172

---- restricted, 8, 9, 30, 50, 58, 64

---- separate for male and female Cuckoo, 144

---- song, its relation to the, 119-68

---- temporary desertion of, 28, 35, 58, 59

---- and hostility, relationship between, 242

Thrush, Song, 222, 244

Tit, Blue, 221, 226

---- Great, 221

---- Long-tailed, 226

Tradition, 300

Tree-Pipit, 51, 188, 189, 222, 232, 244, 278

Turtle-Dove, 126, 232

Union of sexes, 12

Ussher, H. B., on the hostility between Choughs and Hooded Crows
and Choughs and Ravens, 227

Vocal Imitation, 156, 157, 161

Voice calls of Curlew, 263

Wagtail, Pied, 86, 155

---- Yellow, 278

Wanderings from land, Guillemots, 193

Warbler, Garden, 223, 225, 230

---- Grasshopper, 39, 131, 139, 155, 187, 244

---- Marsh, 39, 40, 52, 81, 132, 140, 155, 156, 225

---- Reed, 49, 51, 68, 81, 132, 140, 152, 153, 211, 225

---- Savi's, 139

---- Sedge, 25, 44, 152, 226, 244

---- Willow, 25, 47, 50, 51, 80, 91, 140, 187, 211, 232, 244, 273

---- Wood, 50, 51, 132, 221

Warfare between different species and its relation to the territory,
215-58

Warning notes, 119

---- of danger, 269

Water Rail, 218

Wheatear, 25, 51

Whimbrel, 140

Whinchat, 39, 50, 51, 81, 222, 232, 233, 234, 244

Whitethroat, 25, 50, 68, 69, 124, 140, 182, 187, 189, 190, 213, 230,
244

---- Lesser, 230, 244

Wild Duck, 250

Will, the, to fight, 102

Willow-Warbler, 25, 47, 50, 51, 80, 91, 140, 187, 211, 232, 244, 273

Winter assemblies, 262-63

Witherby, H. F., in _British Birds_, on the return to former
breeding-ground, 281

Wood-Owl, 156

Wood-Pigeon, 219

Wood-Warbler, 50, 51, 132, 221

Woodpecker, Lesser Spotted, 237

---- Great Spotted, 237, 238

---- Green, 20, 71, 156, 208, 218, 237

Wren, 244

Yellow Bunting, 28, 30, 47, 64, 140, 159, 162, 183, 187, 188, 189,
235, 236, 286

Young die in nest from exposure, 184, 185

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End of Project Gutenberg's Territory in Bird Life, by H. Eliot Howard