to - 
continually courted the female while she ms brooding © nd he 1 
been r-\ ee tedly A||AdH4 by her talbanl l However a few days 
after hatching the 4 A rnSwwd signs of wanting to brood the chicks 
and even did so* He sirs ted feeding the® t gredue lly took 
acre and sore art until his contribution was a© arab t es toe 
two .-a rents ixgthteH together. The foi lowing trfrie show© 
the perooti t-' -’® of feedings I witnessed by the thre birds 
in the first and second twenty day© after hi tching* 
?ot«l no. of feedings 
observed 
l.vs 1 e 
Contributions* 
Fefij&le 
Kxtr bird 
First ST 
ye 
S 4 
Second "0 dry© 
4 f 
33.t 
1 
14 S 
48> 
In another neat In ! r;F >3 I saw that a third bird was -laying a 
part in Incubation. He first a -speared to tike :■ special 
interest in tts brooding fesiaXe .«o®e i or she laid* 
At first he courted- her and wa© driven off but after a time he was 
even allowed to relieve hor on the eggs* Tho husbnnl • ' ! e first 
drove him .off whenever he found th« s bt ranger at the neat but 
Is ter, I thli s ace< .®d^®In . Id *5 Ire I look-out 
for the possibility of * triple /fronts’*. In two nests It 
pearc dev&r but one nest was accidentally destroyed 
and the other hatched and the tyoung moved out of ay wegt of 
vision. In both cases the additional bird behaved like t sale* 
In a great many other nests* ©Hi . s nearly e half* there were 
additional bird 3 who behaved a© unmet -'A an ice and courted the 
brooding females with gr-st intensity and even tried to ® u*t 
the®. In this they were scuetioaS successful but the? fo®a le 
would always rise from the nest and try and get rid of the®. 
At sever*' 1 nest© I was able to Identify these extra male© and 
found that it was • always tl saoe bird who wouJ 9 pestering 
the brooding fern-, le day after -lay. Although they were unable 
to dowel o-.. a normal rel© I Rum to the brooding fewale they . 
showed a clear preference for one particular bird* and showed 
their feelings for her as far as she waul ? allow them. 
tome . 
oxce -X 
y oung • 
In 1 3 the facilities on th ue were also used to 
study the growth rate of the t reus in the Arctic and Com on 
The i 1 means MAmrtn the length Is laws t© rial 
th t it was constant in all my measurements of all the 
The tarsus length of young of known age was measured 
in as many young aa possible but It iso rarely feasible, especially 
In the Cession tern to got more than a few values ( some time© only 
one) for each day of age. The figure below shows that 
although the mean le greater in the Coon-on torn from th d y pi 
hatching onward, the actual measurement© overlap at first in 
the two species. On y when the young t re over a week old do 
the measurements effectively cease to overli ■■* Thuo even if 
a standard method of *e*. aurin 5 could be described and wa© carried 
