The first case of homosexual necrophilia in the mallard Anas platyrhynchos (Aves: Anatidae)

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The all glass façade of the extension of the
Natuurmuseum Rotterdam, situated in an
urban park, acts - under certain light condi-
tions - as a true mirror (Fig. 1). Numerous
birds, mostly trushes, pigeons and wood-
cocks, die in collision with the building.
Especially during the first months after the
new wing was erected in 1995, a 'bang' or a
sharp 'tick' on the window meant work for the
bird department.
THE CASE
Such was the case on 5 June 1995 at 17.55 h.
An unusual loud bang, one floor below my
office (Fig. 1), indicated yet another collision
and an addition to the bird collection. I went
downstairs immediately to see if the window
was damaged, and saw a drake mallard (Anas
platyrhynchos LINNAEUS, 1758) lying motion-
less on its belly in the sand, two metres out-
side the façade. The unfortunate duck appar-
ently had hit the building in full flight at a
height of about three metres from the ground
(Fig. 1). Next to the obviously dead duck,
another male mallard (in full adult plumage
without any visible traces of moult) was pres-
ent (Fig. 2a). He forcibly picked into the
back, the base of the bill and mostly into the
back of the head of the dead mallard for
about two minutes, then mounted the corpse
and started to copulate, with great force,
almost continuously picking the side of the
head (Fig. 2b). Rather startled, I watched this
scene from close quarters behind the window
(Fig. 1) until 19.10 h during which time
(75 minutes!) I made some photographs and
the mallard almost continuously copulated his
dead congener. He dismounted only twice,
stayed near the dead duck and picked the
neck and the side of the head before mount-
ing again. The first break (at 18.29 h) lasted
three minutes and the second break (at 18.45 h)
lasted less than a minute. At 19.12 h, I disturb-
ed this cruel scene. The necrophilic mallard
only reluctantly left his 'mate': when I had
approached him to about five metres, he did
The first case of homosexual necrophilia in the
mallard Anas platyrhynchos (Aves: Anatidae)
C.W. Moeliker
Natuurmuseum Rotterdam
Moeliker, C.W., 2001 - The first case of homosexual necrophilia in the mallard Anas platyrhynchos
(Aves: Anatidae) - DEINSEA 8: 243-247 [ISSN 0932-9308]. Published 9 November 2001
On 5 June 1995 an adult male mallard (Anas platyrhynchos) collided with the glass façade of the
Natuurmuseum Rotterdam and died. An other drake mallard raped the corpse almost continuously
for 75 minutes. Then the author disturbed the scene and secured the dead duck. Dissection
showed that the rape-victim indeed was of the male sex. It is concluded that the mallards were
engaged in an ‘Attempted Rape Flight’ that resulted in the first described case of homosexual
necrophilia in the mallard.
Correspondence: C.W. Moeliker, Natuurmuseum Rotterdam, P.O. Box 23452, NL-3001 KL
Rotterdam, the Netherlands; e-mail moeliker@nmr.nl
Keywords: homosexuality, necrophilia, non-consensual copulation, mallard, Anas platyrhynchos

not fly away but simply walked off a few
metres, weakly uttering series of two-note
'raeb-raeb' calls (the 'conversation-call' of
Lorentz 1953). I secured the dead duck and
left the museum at 19.25 h. The mallard was
still present at the site, calling 'raeb-raeb' and
apparently looking for his victim (who, by
then, was in the freezer).
The secured specimen
Natuurmuseum Rotterdam, NMR 9997-00232, adult
male (gonads seen and preserved), study skin (skull in
situ), 05-VI-1995, The Netherlands, Rotterdam,
Museumpark, leg. C.W. Moeliker; skin preserved by
E.J.O. Kompanje, 25-VIII-1995. MEASUREMENTS (in
mm): culmen to feathers 55.3, culmen to nostril 43.0,
tarsus 42.0, midtoe with nail 71.0, midtoe without nail
62.0, wing 272.0 (right), 273.0 (left), tail 89.2.
BARE PARTS: bill dark olive-green, foot orange red.
PLUMAGE AND MOULT: The bird is in adult plumage and
had just started the post-breeding moult into the eclipse
(non-breeding) plumage: two central pairs of tail feathers
shed, with new growing; scapulars, feathers of chest,
breast, belly, back and flanks in full moult; rest of plum-
age unmoulted and still in (worn) adult breeding condi-
tion (Fig. 3). See: Cramp & Simmons (1977).
DESCRIPTION:(of plumage characteristics): crown and
forehead dark green with a blackish wash, hindneck dark
green with a bluish wash, chin at the base of the lower
mandible cream white for about 1 cm and grading into
dark green, earcoverts dark green mottled with light
brown (black centred) feathers, ring around lower neck
white (but not so dorsally), below the white ring the
chest is chestnut ventrally, mixed with (newly moulted)
blackish grey feathers edged buff, breast chestnut but
mottled with more (blackish grey) buff-edged feathers,
244
DEINSEA 8, 2001
Figure 1 The new north wing of the Natuurmuseum Rotterdam. a= the office of the author; b= the approximate location
where NMR 9997-00232 hit the glass façade; c= the site from where the author observed the rape (from behind the glass).
[photo: Christian Richters]
Figure 2 aDrake mallard (Anas platyrhynchos) in full breeding plumage (left) next to the dead drake mallard (NMR 9997-00232)
just after collision with the new wing of the Natuurmuseum Rotterdam; bthe same couple during copulation, two minutes after
photo awas taken. [photo: C.W. Moeliker]
ab

feathers of lower breast and flanks grey with buff edges
and centred light buff (newly moulted), belly white and
finely vermiculated pale grey - spotted blackish grey due
to newly moulted feathers, lower belly like breast, lateral
undertail coverts black, central undertail coverts white
with black spots, tail greyish white ventrally, hindneck
(dorsally) vermiculated grey, back and rump blackish
with a bluish wash, scapulars brown grey edged buff,
primaries and tertials brown grey, secondaries brown
grey tipped white (outer webs glossed blue), greater
upperwing coverts grey (edged white and black), lesser
upperwing coverts whitish grey, (unmoulted) tail feathers
dorsally grey-brown edged and tipped white, newly
moulted and still growing central tail feathers dorsally
black edged buff. GONADS AND PATHOLOGY: Dissection
revealed that the specimen is indeed of the male sex:
testes were yellow, fully developed, measured 28 x 15
mm each and were not in a reproductive state. Collision
with the museum building had caused the following lethal
internal damage: severe haemorrhages in the brain,
rupture of the right lung, trachea and liver, both scapula
broken, most ribs broken close to the sternum (might be
caused by the prolonged copulation); otherwise in good
condition. Stomach empty.
The Museumpark mallards
The Museumpark in Rotterdam has several
ornamental water-bodies, such as ponds and
ditches, which house a more or less sedentary
free-living mallard population of about 40-50
full-winged individuals. About 25% of the
population consists of hybrids between the
wild type and the white domesticated mal-
lard. The majority shows no aberrant plum-
age characteristics and is apparently of wild
origin. The mallards are rarely fed by humans
and are not particularly tame, although cer-
tainly not shy. About 10-12 pairs breed, and
the first ducklings are seen in early April
(pers. obs.). The closest water-body, a 10 m
245
MOELIKER: homosexual necrophilia in the mallard
Figure 3 Drake mallard (Anas platyrhynchos), NMR 9997-00232, specimen still in the flesh, moulting into non-breeding (eclipse)
plumage; adorsal view, bventral view. [photo: C.W. Moeliker]
ab

wide ditch that runs for about 750 m along-
side the whole length of the Museumpark, is
located just a few metres north of the new
wing of the Natuurmuseum Rotterdam.
DISCUSSION
Although I did not actually see the events
preceding the moment NMR 9997-00232 hit
the building and died, I strongly believe the
two mallards were involved in some kind of
aerial chase or pursuit flight: the victim flew
into the building in full flight and the drake
that pursued, managed to prevent a collision
and landed next to the dead duck. I watched
the scene immediately (less than a minute)
after the tremendous bang and saw the drake
next to its dead congener (Fig. 2a). It is there-
fore highly unlikely that the drake was just
passing by, saw the corpse and started to rape
it. When we disregard the homosexual nature
of this case, the pursuit-behaviour the mallards
were involved in, is common (and also often
observed in the Museumpark). After the break-
up of the pairs (from mid March onwards),
when the drakes congregate in small flocks,
more than a dozen may chase a single female
in the air, trying to force her down and rape
her (Geyr von Schweppenburg 1953, 1955;
Weidman 1956). Lebret (1961) calls this
behaviour 'Attempted Rape Flight' (ARF) and
Cramp & Simmons (1977) speak of 'rape-
intent flights'. I could however only find refe-
rence to heterosexual ARF's (or any other
pursuit-flights) in the mallard. Homosexual
rape or attempted non-consensual copulation
- as such - is known in the mallard (Bagemihl
1999, see below). The true homosexual nature
of the case described here could be verified
by inspection of the gonads: my initial
thought that NMR 9997-00232 was a senile
female wearing a male plumage (see: Post &
Kompanje 1992) proved wrong. The plumage
of NMR 9997-00232, although moulting into
the non-breeding (eclipse) stage, still showed
enough male features (Fig. 3) to judge a
'mistake' by the raping drake (that was still in
full breeding plumage [Fig. 2a]) as highly
unlikely.
Homosexual rape
Bagemihl (1999) in his well-researched and
exhaustive overview of animal homosexuali-
ty, showed that in the mallard 'the proportion
of male homosexual pairs varies between
populations, anywhere from 2-19 percent of
all pairs'. So, male homosexuality can be
regarded as a common phenomenon among
mallards. According to Bagemihl, drake pairs,
however, do not exhibit overt sexual activity:
they normally only show behaviour that pre-
ludes copulation but neither partner mounts
the other. Interestingly, Bagemihl (1999)
noted that 'some males in homosexual pairs
have been observed attempting to rape or for-
cibly copulate with males outside their pair-
bond'. Initially, this may have been the case
on 5 June 1995: the drake attempted to rape
NMR 9997-00232 who fled, and the two got
engaged in a true homosexual ARF.
Necrophilia
What still remains is the fact that NMR 9997-
00232 was dead while he was being raped
(one may argue that the copulation was no
rape, but the act was non-consensual any-
how). Surely, this must have influenced the
duration of the copulation. Necrophilia is
known in the mallard, but only among hetero-
sexual 'pairs': 'Occasionally, males even try to
mate with dead females' (Bagemihl 1999). To
the best of my knowledge, this case is the
first described case of homosexual necro-
philia in the mallard.
ACKNOWLEDGEMENTS
I am greatly indebted to dr Erwin J. O
Kompanje who executed the autopsy, prepa-
red the skin and critically commented on the
manuscript. He also urged me to write this
note (for almost six years) and discovered
Bagemihl (1999), which proved to be indis-
pensable. Mr Willem Beekhuizen shared his
knowledge about ducks, and dr Jelle W.F.
Reumer added useful comments to the manu-
script.
246
DEINSEA 8, 2001

247
MOELIKER: homosexual necrophilia in the mallard
REFERENCES
Bagemihl, B., 1999 - Biological Exuberance, Animal
Homosexuality and Natural Diversity - Profile Books,
London
Cramp, S. & Simmons, K.E.L., 1977 - Handbook of the
Birds of Europe, the Middle East and North Africa,
The Birds of the Western Palearctic, Volume 1 Ostrich
to Ducks - Oxford University Press, Oxford
Geyr von Schweppenburg, H., 1953 - Zum Reihen
der Enten - Journal für Ornithologie 94: 117-127
Geyr von Schweppenburg, H., 1955 - Und nogmahls:
Vo m Reihen - Journal für Ornithologie 96: 371-377
Lebret, T., 1961 - The pair formation in the annual cycle
of the mallard, Anas platyrhynchos L. - Ardea 49: 97-
158
Lorentz, K., 1953 - Comparative studies on the beha-
viour of the Anatinae - London
Post, J.N.J. & Kompanje, E.J.O., 1992 - Uitwendige
geslachtsverandering bij vrouwtje Wilde Eend -
Dutch Birding 14: 131-134
Weidmann, U., 1956 - Verhaltensstudien an der
Stockente (Anas platyrhynchos L.) - Zeitschrift für
Tierpsychologie 13: 208-271
Received 11 October 2001
Accepted 12 October 2001

248
DEINSEA 8, 2001
DEINSEA - ANNUAL OF THE NATURAL HISTORY MUSEUM ROTTERDAM
P. O.Box 23452, NL-3001 KL Rotterdam The Netherlands