Chapter VIII.--Order Charadriiformes (Family Laridae; 
Gulls and Terns) 
Caspian Tern 
Literature on productivity and Survival 
A.-H. Miller (1943) in a census of a colony of Hydroprogne 
caspia found the mean number of eggs in 325 nests to be 1.8. 8 
same colony 51 other eggs were scattered about outside of the nests. 
Miller found the average number of young to be 1.5 in 37 nests. 
The age at which this species breeds seems to be unknown. 
O. L. Austin, Jr. (1932) and 0. L. Austin (1942) in their work on a 
smaller bird, the common tern (Sterna hirundo), found that an ap~ 
preciable fraction of the younger birds do not appear to begin 
breeding until they are 4 years old. 
According to Ludwig (1942), the greatest mortality among 
banded caspian terns occurs in the first 6 months of life. 
Banding work in North America 
Of the more active banders working from 1926 to 191 on 
this species, F. C. and C. C. Ludwig ringed 4650 birds for 53 recoveries, 
W. I. Lyon ringed 4257 for 71 recoveries, Adam Brown ringed 1426 for 10 
recoveries, and H. E. Alcorn ringed 1063 birds for 6 recoveries. 
Recovery rates for 9 successful banders were 2.1 per cent for 3305 
birds banded 1926-32 and 0.9. per cent for 8786 ringed from 1933 
through 1941. Only recoveries reported up to August 31, 19,5, were . 
included in these totals. | 
Characteristics of the samples studied 
The monthly variation in recovery reports (table 37) dis- 
closes no important differences between first-year and older birds. 
They may, of course, appear when a larger sample is available. 
Most of the caspian tern recoveries originated from Great 
Lakes bandings. There is an obvious migration of these birds to 
Lake Erie, thence overland to the Atlantic coast (Long Island to 
Chesapeake Bay), and so south to Florida and the West Indies. 
Important wintering grounds for both young and adults include 
Florida, Louisiana to Alabama, and Colombia. The lack of reports 
from Mexico suggests that Colombia is not reached by following the 
ccast. An excellent picture of this migration has been given by 
Ludwig (192). 
Abridged life table 
Table 38 represents a preliminary estimate of mortality 
based cn only 106 caspian tern recoveries. Of these, 71 were 
88 
