ENDERBURY 
Dr AFT 
birds 
Gray**backed T ern ( Sterna lurnta) 
Current Status: Com-ion resident and nesting species, i-kximum POBSP population 
estimate; 3000 in November 19:63. Minirauin POBSP population estimates; 200 
in February 1964. 
rQv'U ' G. G. Ifunro (19 ■ a} found 
Fresh eggs on July 26, 1938 and in tt 
xj-nr- 
’James 9 A Kinney banded 200 adults on April 1A .^addition L.P. Schultz 
collected a si le or: Kay 1$, 1939 
Gor 
Popul-Qtion: The gGray—backed Tr.o. — r.colnitc tc ' ijc j en jy * , , ’ fc c .' '* t y g less frequent 
on mia-vvinter (February) and. most abundant in late Spring, Summer and 
Fall (lay-June, July and November) but population fluctuates far less in 
vv'*y>*. 1 W vfe di,o 
proportion to the . than i fo?nrr ! mr-^*e Sooty Tern. . 
EBxinuni 
The breeding population seems quite variable but the MMMi breeuinr 
o 
i v\ 
population fsa©$a 1963 
9t>5 been about 450-750 pairs. The 
annual breeding population may be of the order of 600-1000 biros allowing f 
or 
breeding activity Which may have occured in the intervals between POBSP 
visits „ 
Annual Oye e: Although nests wit:: eggs or young have been present on all seven 
visits, there 4-s seems to be a quite definite 7 annual cycle . Our nest data 
presented in table 
indicates an annual laying peak sometime between May 
and early July. If much egg laying occurred antecedent to May or subsequent to 
August we h would nave expected to have found fairly large numbers of immature 
birds in May 1965 and in November 1963 and 1964. In fact, very few inmture birds 
Table 
•_ ' - — - 
Gray bac ed Tern nest counts bn under bury Island 
February 
November 
sryybi 
. 
07 
■ £- I 
-fra ; y- 
150-100 
A9 ' - ff : W- 'F "' - ' 
r A . 5 
■ 
. - • ; - 
: . ■ : - 
> ... " -■ > 
■■ ■ ' - '-. - .V. 
■ ■ 
l xii st xxgure r*prts the number of ne sts with egas and the second fi 
S-l- ... 1 _l.1_ 1 » 1 ■ '• — 
is; the na Fi r vith chicks. 
