35^ BROOKLYN INSTITCTE MUSEUM. SCIENCE BULLETIN 2. 6. 
frnm the mouth up ahniost to the first falls above Perico. It keeps 
to the tops of the low trees which overhang the water and on the 
buds and leaves of which it feeds. Colonies occupy the same general 
area during the entire year, but at the approach of the breeding 
season, which varies considerably in different localities along the 
river, the flocks break up into pairs, each pair keeping to a restricted 
area of the general breeding grounds. 
The breeding season about Caicara lasts from early in June until 
mid September. In 1905 I took the first set of eggs June nth. 
Freshly completed nests had been noted as early as May 25th, when 
I went scouting for them, but at that time they must have been from 
five to seven metres above the water. The nest found June nth was 
between three and four metres above the water at nearly what would 
1)0 high water mark. On June i8th, seven sets of eggs were collected. 
With the exception of one set of two, all were fresh. 
In my field record for that date I made the following entry: 
Although Hoatzin are never hunted and very rarely disturbed in 
their haunts they are nevertheless decidedly shy. Sitting birds would 
always leave the nest when, or even before, we came in sight of the 
same. The parent birds never remained near the nests and by actions 
manifested l)ut little concern in what was going on. .\ests are 
apparently never placed very close together as in a heronry. T have 
rarely found them nearer than from twenty-five to fifty metres froin 
one another. 
Of the seven nests containing eggs found on this date, none were 
over 1.2 m. above the level of the water. The average was about 
one meter, although one was only about 45 cm, up. At the rate the 
river is rising the lowest of these nests would be under water before 
the week is over. 
On June 22nd seven additional sets of eggs were collected. The 
nests were on an average between i to 1.25 m. above the water at that 
time, which means that they would be at the water level, or below, by 
the time the eggs would be hatched. 
My observations indicate that the nesting season on the Orinoco 
is controlled to a large degree by the water level in tlie river. The 
ovaries of nearly all the Hoatzin collected near Bolivar about the 
middle of April indicated the approach of the breeding season. Speci- 
mens collected at Caicara early in ^lay did not show a more active 
condition of the ovaries, but ns I have stated above, completed nests 
