STUDY OF BIRD BEHAVIOUR 601 



material. Other nests : material inside and out, and, if any, between the lining and exterior. 

 For all types of nest : where material obtained. Fresh or dry, if vegetable. Is more than one 

 nest made by the same pair ? Use of same. 



(d) Building. By which sex is the ground scrape made. By which lined. If by both, 

 share of each. If one, what does mate do? (See vol. iii. pp. 372-379.) Share of sexes in building 

 hole and other nests. Detailed description of building (scrape, lining ; foundation, shaping, 

 collecting material). How long to complete. Interval between completion and laying. Causes 

 of desertion. 



(e) Variation. Variation within the species with respect to area, site, lined and unlined 

 scrapes, shape, material. For example, see vol. i. pp. 374-380. Differences between species in the 

 same group. 



(/) Instinct and intelligence. Note if nests of year-old birds, that have no opportunity of 

 imitating others, are those of their species. These can best be observed in captivity; but also 

 in the wild state, if ringed or otherwise recognisable. Note if improvement shown in second 

 and succeeding nests. 



(cj) Cleaning of nest. In what way are the f;eces of young disposed of by the parents ? 

 Are they eaten or dropped ? At what date after birth do parents cease to remove them ? 

 Why? 



(k) Second nest. Is a new nest built for second or later broods ? If not, is old nest cleaned 

 or repaired ? Is new nest in same nesting area as first ? 



Literature : C. Lloyd Morgan, Habit and Instinct, pp. 232-239 ; W. P. Pycraft, History of 

 Birds, chap. xi. (Methuen); A. R. Wallace, Natural Selection and Tropical Nature, chapters 

 on the " Philosophy " and the " Theory of Birds' Nests " (Macmillan). The last named should 

 be read in connection with the first. 



4. Incubation. By which sex, share of each. Date on which each egg laid, incubation 

 begins, each egg hatched, the eggs being numbered. Effect of weather, latitude, situation of 

 nest upon date of laying, and period of incubation. Weight of eggs as incubation proceeds. Is 

 incubating bird fed ? Are eggs covered when left ? Are they turned, how often, in what 

 manner 1 The information available as to period of incubation and date of laying will be 

 found for each species in the " Classified Notes " of this book. This might be verified, as well as 

 completed. 



5. Nestlings and Fledglings. Period in nest. Rate of growth tested by weight 

 and measurements. Immediate cause of departure. Where they go on leaving nest. Rela- 

 tions with parents when preparations for second brood started. Relations with second or later 

 broods. See also " Feeding " and " Protection of Young." 



6. Feeding. (a) Choice of food is primarily determined by inherited likes and dislikes. 

 But is the selection of the appropriate food a matter of instinct or experience ? This is tested 

 by watching young birds, when able to feed themselves, and under conditions that exclude 

 imitation. For observations on nidifugous young see Lloyd Morgan, Habit and Instinct, 

 chap, ii., and Animal Behaviour, pp. 93-98. Nidicolous fledglings have not been studied. 



(b) Methods of feeding and tending young. Exact descriptions. Instinctive or acquired ? 

 Tested by watching parent birds when undertaking parental duties for the first time under 

 conditions that exclude imitation. Share of parents in feeding or tending. Do cock and hen 

 bring different food to nest 1 Visits with food per hour and day. Time of day when visits most 

 frequent. Distribution of food among young ; which, if any, get most and why. Death of 

 weaker nestlings. Cause. Preparation of food for young, whether by digestion, maceration, or 

 division. Form of food given at different stages of growth. Literature : W. P. Pycraft, 

 History of Birds, chap. xiv. 



(c) Methods by ivhich the young, that are fed by their parents, respond to food stimulus. 



