202 INTEODUCTOEY CHAPTEE. 



When the young are strong enough to take wing, they 

 abandon the family tie, and soon lose themselves in the great 

 world of nature, forgetful of their parents' unselfish care. The. 

 ingratitude of their first-born does not, however, discourage the 

 forsaken couple. With the returning season they renew their 

 labours, exhibit the same solicitude, the same affection, to meet 

 with the same return. Nature is an unfailing source an eternal 

 focus of tenderness and love. 



Most families of birds are migratory ; that is, they abandon their 

 summer quarters and undertake long journeys at certain seasons. 

 These migrations occur with the greatest regularity. By their 

 departure from temperate or cold climates they prognosticate the 

 approach of winter, as their return heralds spring. Among 

 the ancient Greeks, as we learn from a passage of Aristophanes 

 on birds, the arrival of the CRANE pointed out the time of sow- 

 ing ; the arrival of the KITE the sheep- shearing season ; and the 

 arrival of the SWALLOW in Greece was the date for putting off 

 summer clothing. The impulse which causes birds to depart is 

 an instinctive desire to find climatic conditions appropriate to their 

 wants of life. At the approach of winter they desert the regions of 

 the north in search of southern countries with a warmer climate, 

 while others migrate northwards to escape the heat. 



Nevertheless, all birds are not migratory ; many species remain 

 during their whole lives in the locality where they were hatched, 

 straying but little distance from their birth-place. The majority of 

 those which migrate perform their journeys annually and with 

 great regularity ; a few irregularly and accidentally ; that is, they 

 are caused by necessity, or by atmospheric influences, to change 

 their residence ; and it is no unusual sight on such occasions to 

 see numerous flocks of birds assembling under the leadership of a 

 chief, and taking their flight in perfect order, traversing seas, 

 and passing from one continent to another, with astonishing 

 rapidity. On the 22nd of September, 1771, White, of Selborne, 

 witnessed the flight of a flock of Swallows which had rendez- 

 voused the night before in a neighbour's walnut-tree. " At dawn 

 of what was a very foggy day, they arose all together in infinite 

 numbers, occasioning such a rustling from the strokes of their 

 wings against the hazy atmosphere that the sound might be heard at 



