Family HIRUNDINIDAE. 

 Delichon urbica (L.) — Martin. 



(Plate 83, fig. a-c). 

 (Snouckaert: Avifauna Neerlandica, p. 53, No. 127). 



Colour of surface of shell: 

 Colour of spots: 

 Average dimensions: 

 Average weight of shell : 

 Texture of shell : 



Shape : 



Nest: 



Site of nest: 



Number of eggs: 

 Breeding season: 



Duration of incubation 

 * Remarks : 



white, with a weak gloss. 



see the subjoined remarks*. 



18.3 X 13.2 millimetres. 



0.104 gram. 



bears no special characteristic; I cannot sup- 

 port Bau's assertion that faint longitudinal 

 grooves often occur at the pointed end of 

 the egg. 



oblong ovoidal, pointed. 



is built of clay, or muddy earth, mixed with 

 viscous saliva, and lined with feathers and 

 little bits of straw; the entrance is made 

 on one side. 



against the exterior of buildings, under eaves, 

 gutters, etc.; also under bridges, and in 

 similar places; often in colonies. 



5 (after-set: 4). 



end of May— August (sometimes even in 

 September). 



about 13 days. 



On some eggs specks occur of a darker colour than the 

 spots of rustica-eggs; in most of these cases these 

 specks are undoubtedly formed by excrements of nest 

 parasites, and not by pigment. Nevertheless, eggs 

 really speckled with pigment appear to occur occa- 

 sionally ') and older writings already mention such 

 eggs (Klein, Bechstein, Thienemann). 



W. SCHUSTER considers that Hrfi/ca-eggs are in a tran- 

 sitionary stage towards a spotted type, and states 

 that in his birthplace (situated in Oberhessen) most 

 eggs are dotted over with distinct dark brown specks. 

 According to HAGENDEFELDT this is also the case 

 in Sylt 2 ). 



In 1907 a set of eggs was found near Newbury (South 

 England, Berkshire) which is described as „marked 

 with small red spots". 



') The description of the eggs in SCHLEQEL (Nat. Hist. v. Nederland, De Vogels, 1868, p. 46) to 

 the effect that they are always speckled over with brown and red, is of course founded on an error. 



2\ I,..,,-,,-,! f Orn;tl, n lmr; a Si / 1 fWl , r. OT 



2 ) journal f. Ornithologie. 51 (1903 , p. 23 



