30 
Gray-backed Tern ( Sterna lunata ) 
Current status ; Breeds annually 
Prior Records ; Munro (l94l) saw this species off Nihoa, May 26,“27 1891. 
Other records are Fisher (1906), Munter (1915)> Wetmore (1923), Vanderbilt 
and de Schauensee (1941), Woodside and Kramer (I96I). 
Population: Munter (op. cit) estimated 10,000 on March 18, 1915 and Wetmore 
(op. cit) also estimated 10,000 during his visit from June 11-16, 1923- 
Woodside and Kramer (op. cit) recorded them as abundant March 2, 1961. 
So>Xr6Y 7*#* Ty Pn* T Y 
The P0BSP of March 6, 1964 estimated 100 birds while the of 
March 24, I965 estimated 5>000. 
Reproduction : Fisher (op. cit) observed birds in immature plumage between 
August 5-10, 1902. Munter (op. cit) reported flushing two adults from 
eggs on March l8, 1915 but he does not give any nest estimates. Wetmore 
(op. cit) between/'ll-l6 > 1923, estimated. 5,000 nests, "most -with fresh eggs, 
some newly hatched young and a very few young about half-grown." Vanderbilt 
and de Schauensee (op. cit) between August 7-15, 19^-0 found two small colonies 
in the last stages of breeding, haying only nestlings. Kramer and Beardsley 
(op. cit) saw eggs and downy nestlings June 10, 1962. 
The breeding data from three P0BSP trips show the progression of the 
st/Rv6Y rflAvy 
breeding cycle. The t^£p of March 6, 1964 estimated 25 nests, only a few of 
which j as yet ; had eggs. The March 24, 1965 showed laying well advanced 
with an estimated 2,500 nests with eggs. The brip of September 24-25, 19 d 4 
counted six immature s remaining on the island. 
When the prior breeding records are added to the P0BSP records there are 
three records of eggs in March, two records of eggs and nestlings in June, one 
record of nestlings in August and one record of immatures in September. 
This delineates a breeding season beginning in early March and ending in late 
Sept ember. 
