NOTES AND QUERIES. 399 



bution of birds is a very interesting and complex question. The 

 sudden irruption of the Hawfinch as a breeding species a few years 

 ago into Yorkshire raises a curious question. — B. P. Buttekfield, 



A Luminous Owl. — Two years ago, while walking along the flank 

 of an Essex woodland an hour or so after sunset, I had a momentary 

 glimpse of a luminous patch moving in the air at my right hand, 

 some fifty or sixty yards away. Turning my head, I recognized the 

 object as a Barn-Owl ; my wife was with me, but by the time I had 

 called her attention to the bird it was invisible. The then recent 

 discussions of " luminous Owls " came to my mind, and before 

 leaving the spot I made one or two observations and simple experi- 

 ments which served to throw light on this particular instance of 

 the phenomenon, and may perhaps be of more general application. 

 Our path was across a pasture, parallel with the woodland a 

 hundred yards away ; and exactly opposite a full moon was just 

 clearing the mists on the horizon. The trees were quite dark, for 

 their almost bare twigs reflected little light. The Barn-Owl in life is 

 extremely sleek and even glossy in plumage, and the under parts of 

 this bird were not only white against the dark trees, but probably 

 acted also as a mirror reflecting the moonlight. When I first 

 detected it, the Owl was overtaking us, so that I saw it sideways, at 

 a wide angle. (From this position the eye is very sensible to such 

 objects as faint stars.) My first impression was that I had seen a 

 moving light, but this was a very momentary feeling, for when I 

 turned my head and looked directly at the bird, it was merely 

 whitish, with little suggestion of luminosity. In a few yards it came 

 opposite a more distant and therefore greyer background, and was 

 not nearly so striking ; and a second later the Owl was against the 

 sky — too inconspicuous for my wife to pick up, but visible to me for 

 some further time. The experiments were made by means of hand- 

 kerchiefs and white paper against various backgrounds, and were 

 repeated on a subsequent occasion. I can sum up by saying that I 

 saw a Barn-Owl luminous against a dark background, decidedly not 

 luminous while still visible against the paler distant trees, and 

 invisible against the sky. Here one could hardly entertain any idea 

 of phosphorescence or other similar source of light ; but had the 

 circumstances provided an unbroken and very dark background, 

 with appropriate conditions of moonlight, there would have been 

 less confidence in dismissing the theory of the bird being actually 

 the source and the carrier of the light. The Barn-Owl often strikes 

 me as being exceedingly white when it is on the wing in the 



