Diving by wintering puddle ducks
A N D R É B O U R G ET AND
G IL L E S
Foraging dives by surface-feeding ducks have
been reported in several species o f w aterfowl
(K ear & Johnsgard, 1968), and occur m uch
m ore frequently th an is generally appreciated
(Johnsgard, 1968), although there is little
precise inform ation published on this type o f
behaviour, nor on the extent to which it oc­
curs under natural conditions.
This note describes the diving behaviour
an d ability o f th ree species o f p u d d le
(dabbling) ducks wintering in the vicinity o f
M ontreal and discusses its im portance to
ducks wintering in harsh conditions.
D a ta were collected by observation from
vantage points while doing w inter surveys.
Spotting scope with oculars varying from
15x to 4 0 x and stopw atches were used to
register diving tim es o f w aterfowl. O bser­
vations on times o f dives were m ade over a
tw o-day period at the end o f F eb ru ary 1974.
G eneral observations were m ade throughout
the w inters o f 1971—1974.
Lake St. Louis, an enlargem ent o f the St.
Law rence River n ear M ontreal, possesses
several areas o f rapid flowing w aters th at are
free o f ice th roughout winter. D espite the
severity o f the w inter, this locality represents
an im po rtant wintering ground for waterfowl
in Q uebec (Reed & B ourget, in press). D uring
the day, puddle ducks tend to congregate on
choice feeding grounds in shallow w ater, p a r­
ticularly in or near the L achine rapids. Diving
ducks are scattered in small feeding groups
over the open w ater.
Shallow w ater areas are particularly liable
to freeze over during cold spells, rendering the
typical dabbling duck feeding areas unusable.
Loss o f feeding areas at a tim e when w eather
co n d itio n s a re esp ecially sev ere m akes
existence precarious for the dabblers; death
from starvation an d /o r exposure has been
C H A P D E L A IN E
noted am ongst surface-feeding ducks in the
L achine area quite frequently (A. R eed, pers,
com m .) and a severe die-off occurred in 1967
(Reed, 1967).
R esults an d discussion
A n inventory conducted on L ake St. Louis in
Feb ru ary 1974 revealed the presence o f a
population o f about 400 puddle ducks, prin­
cipally Black D ucks A n a s rubripes, with a
few M allard A n a s platyrhynchos and Pintail
A n a s a cu ta . T h e se th re e species w ere
observed repeatedly from late Jan u ary to late
M arch to dive to obtain food.
The ranges and m eans o f diving times for
the three species were sim ilar (Table 1),
although the m ean d uration for the Black
D uck was significantly less than th a t for the
Pintail and M allard (P < 0 05). Both males
and females o f each species were seen diving,
but no significant difference betw een the sexes
in frequency and duration o f dives, as well as
depth o f the area exploited w as evident. Such
differences have never been investigated in
puddle ducks, although Willi (1970) reported
differential feeding p attern s and am ount of
feeding by tw o types o f p artial im mersion
(upending) in male and fem ale Green-winged
Teal A n a s crecca.
The differences in diving times between
th ese th ree species m a y be re la te d to
physiology: O lney (1963) suggested th at
differences in the length o f tim e for which
surface-feeding ducks can m aintain their
heads under w ater could be related to specific
differences in respiratory and circulatory
adaptations, with particular reference to apnoea, the cessation o f respiratory movem ents.
Table 2 is an assem bly o f published inform a-
Table 1. Foraging diving times by wintering surface-feeding ducks near Montreal, Quebec, late February
1974.
Species
Black Duck
Mallard
Pintail
No. of
dives observed
229
154
149
Range of diving
time (sec.)
2-10
2 -9
2-10
Mean diving
time (sec.)
S.D.
4-9
5-2
5-4
1 30
1-51
1-45
55
56
A ndrë Bourget an d Gilles Chapdelaine
Table 2. Published information on duration of feeding dives by Mallard and Pintail and of the period in
which the head can be kept wholly submerged while feeding by tilting.
Species
Range of diving
time (sec.)
Time of head
submergence (sec.)
Source
Mallard
Pintail
6-10, in 1—2 m
up to 10
4 -2 -5 8
4-8-6-2
Szijj, 1965
Chapman, King and Webb,
1959; Szijj, 1965
tion on duration o f feeding dives and head im­
mersion for these species. The perform ance o f
the ducks in the L achine area is consistent
with th at noticed elsewhere, although the oc­
currence o f dives as brief as tw o seconds is
unusual.
It is perhaps w orth rem arking th a t 10
seconds does not represent an upper limit on
the tim e th at A nas sp. can rem ain subm erged.
A s O ring (1 9 6 4 ) re m a rk e d , referrin g to
A m erican W igeon A . am ericana and G adwall
A . streperà, if alarm ed while flightless, puddle
ducks often dive and individuals can rem ain
under w ater for 30 seconds or m ore, often
travelling considerable distances while doing
so.
The depth o f w ater in the feeding area was
not m easured directly. The area w as also
heavily used by A m e ric a n G o ld en ey es
Bucephaia clangula: the mean duration of
114 dives by them w as 20-46 seconds. D ew ar
(1924) found th at the G oldeneye conform ed
well to his 20:10 second rule, an empirical
relationship betw een dive tim es and depths, in
which the average d uration o f dives at one
fathom w as found to be 20 seconds, with an
additional ten seconds for each subsequent
fathom . T hus it seem s probable th a t the p u d ­
dle ducks were diving in about 2 m o f w ater at
Lachine. The brevity o f their dives suggests
that they were spending little if any time at the
bottom , but like coots Fulica sp. were collec­
ting material instantly for sorting and eating
at the surface.
W hen diving for food, the puddle ducks
form ed a very tig h t oblong-shaped group
facing the current, and produced a small
splash when disappearing under the surface.
W hen one o r tw o individuals began diving, all
the m em bers o f the raft soon followed with
fra n tic diving. T h is ‘c o n ta g io u s’ feeding
b eh av io u r u su ally c o n tin u e d for several
minutes. The birds appeared to feed on
vegetation, several individuals being seen to
bring plant rem nants to the surface where
they sorted and ate them .
T hroughout the w inter o f 1973—1974,
Black D ucks, M allards and Pintails associ­
ated regularly w ith G oldeneyes in the Lachine
rapids area. M endall (1949) reported the
association o f Black D ucks and diving ducks
in Maine. He indicated th at roots and tubers
becam e available to Black D ucks after having
been dislodged by the divers. In the w inter of
1970—1971 on the St. Jo h n ’s River, New
Brunswick, the senior au th o r observed a Black
Duck apparently attem pting to usurp food
from G oldeneyes when they had surfaced from
forage dives. However, in the present in­
vestigation no evidence o f dabbling ducks ob­
taining advantages by associating with divers
w as obtained ; the association resulted from the
freezing over o f the typical shallow w ater
feeding areas o f the dabblers which prom pted
them to exploit the deeper w ater diving duck
habitat.
This behaviour trait is probably very im ­
po rtan t for puddle ducks wintering in cold
regions like Q uebec, where shallow feeding
g r o u n d m a y b e c o m e te m p o r a r ily u n exploitable during cold spells. A lthough this
foraging technique m ay be inefficient for
ducks adapted to surface feeding, it m ay con­
tribute to the survival o f individuals which
otherwise would have succum bed under these
severe conditions.
A cknow ledgem ents
Sincere appreciation is extended to Austin Reed
and Hugh Boyd of the Canadian Wildlife Service
for their assistance in preparing this manuscript.
Sum m ary
Observation of foraging dives by Black Ducks
Anas rubripes, Mallard A. platyrhynchos and Pin­
tail A. acuta, were made during the 1973-1974
winter near Montreal, Quebec. Mean duration
diving times from Pintail (5-4 sec) and Mallard
(5-2 sec) were significantly longer than for the
Black Duck (4-9 sec). This type of feeding
behaviour by puddle ducks followed temporary
loss of shallow-water feeding areas during cold
spells.
Puddle duck diving
57
References
Dewar, J. M. 1924. The Bird as a Diver. London: Witherby.
Chapman, S., King, B. & Webb, N. 1959. Pintails diving. Brit. Birds. 52: 60.
Johnsgard, P. A. 1968. Waterfowl. Their biology and natural history. Lincoln: Un. Nebraska Press.
Kear, J. & Johnsgard, P. A. 1968. Foraging dives by surface-feeding ducks. Wilson Bull. 80: 231.
Mendall, H. L. 1949. Food habits in relation to Black Duck management in Maine. J. Wild. Mgmt. 13:
64-101.
Olney, P. J. S. 1963. The autumn and winter feeding biology of certain sympatric ducks. Trans. Vlth
Congr. Int. Union o f Game Biol. 309—320.
Oring, L. W. 1964. Behaviour and ecology of certain ducks during the post-breeding period. J. Wildl.
Mgmt. 28: 223-33.
Reed, A. 1967. Black Duck starvation— Montreal area, February-March 1967. Quebec Wildl. Serv.
Rept.
Reed, A. & Bourget, A. In press. Distribution and abundance of waterfowl wintering in the St. Lawrence
river system of Quebec. Can. Fid. Nat.
Szijj, J. 1965. Ökologische Untersuchungen an Entenvögeln (Anatidae) des Ermatinger Bechens
(Bodensee). Vogelwarte 23: 24-71.
Willi, P. 1970. Zugverhalten, Aktivität, Nahrung und Nahrungserwerb auf dem Klingnaner Stansee häufig
auftretender Anatiden, insbesondere von Krickente, Tafelente und Reiherente. Orn. Beob. 67:
141-217.
André Bourget and Gilles Chapdelaine, Canadian Wildlife Service, Federal Building, 9th floor, 1141 route
de l'Eglise, Ste-Foy, Qué. G1V 3W5, Canada.
A male Red-crested Pochard Netta rufina in the rain (Brian Crosby).