Proposal (352) to South American Classification Committee
Move Anas
platyrhynchos (Mallard) to main list
Effect on South American Checklist: This
proposal would transfer an introduced species from the Hypothetical List to the
Main List.
Background: The Hypothetical List currently reads as
follows: "Sight record from Bonaire (Voous 1985)." Salaman et al.
(2008) presented updated information on the status of this species in South
America, as follows:
"Fjeldså & Krabbe (1990) considered this species to
be common throughout the Andes and naturalized in the Falkland Islands, but
there are no published Colombia records of which we are aware. 35 individuals
were observed and photographed by Thomas Donegan and Blanca Huertas in Parque
Timiza, south-west Bogotá (4°36'30"N, 74°09'09"W) on 3 and 7 January
2008. Birds frequently came to humans for food but also were observed feeding
on grasses. Individuals with both wild-like plumage and extensive leucisms were
observed, perhaps suggesting a captive origin (sometimes referred to as
subspecies 'domesticus'). No individuals had rings on the leg or clipped
wings. Also present were a Muscovy Duck (Cairina moschata) and four
apparent Muscovy Duck x Mallard hybrids. No Mallards were observed at Parque
Timiza in a series of other visits between March 2001 and January 2006, when no
other Anatidae were present at the site.
"Other records of Mallard come from nearby Parque Simón
Bolívar, Central Bogotá (4°39'25"N, 74°05'43"W), e.g. where 8
individuals were present and photographed on 8 February 2008 by Daniel Toro
(http://danxblog.blogspot.com/). 60 individuals were reported in censuses
around Colombia in the 2005 Aquatic Bird Census but no further details are
available (ProAves & RNOA 2005). A single individual was observed at vereda
El Páramo, Villamaría, Caldas (5°00'N, 75°20'W, 3420-4050 m elevation) on 27
December 2004 (ProAves data). Elsewhere in South America, the species is
reported at times in large numbers (but unconfirmed) in Venezuela (Restall et
al. 2006) and there is a sight record from Bonaire (Voous 1985), leading Remsen
et al. (2008) to treat the species as hypothetical for South America. In the
Caribbean, introduced birds or vagrants have been recorded throughout most of
the Greater Antilles (Raffaele et al. 1998). Free-flying individuals have also
been observed in lakes in southern Chile (Jorge A. Tomasevic in litt. 2008) and
Curitiba, Brazil (J. Roper in litt. 2008), in the latter case also hybridising
with Muscovy Duck. These photographic records confirm the status of the Mallard
as an introduced species in South America.
"Johnsgard (1960) noted that hybrids between Mallard
and Muscovy Duck, whilst not uncommon, have reduced fertility. Such
hybridisation should not therefore affect the establishment of the Mallard in
Colombia or elsewhere. Similar establishments of the Mallard have occurred in
many countries (Lever 2005). Conservationists should monitor this introduction
in light of the propensity of the Mallard to hybridise with other ducks,
sometimes threatening native species (Simberloff 1996). It is not known whether
the flocks observed were introduced locally or are wanderers from introduced
populations in Central America and the Caribbean."
Conclusions / Discussion: Mallard should meet concepts
of acceptable introductions for checklists. It is a species that has
established feral populations in many countries throughout the world, with city
park populations even in native Europe often including many leucistic
individuals. A South American photograph has now been published and reasonable
numbers are reported from a number of different localities, including several
in Colombia. Such numbers are similar to or greater than those of some other
species treated by SACC as introduced (e.g. some Estrildidae and Ploceidae).
Project Biomap reports a Colombian Mallard specimen, which
the label notes as being of presumed domestic origin, collected by J.
Durán at Laguna La Ovejera, El Cerrito, dept. Valle in 1957 (Instituto
Vallecaucano de Investigaciones no. 00099).
As BOU guidelines were rejected (Proposal 189), the AOU and SACC
"introduced species" category is rather opaque. Assuming that the
above observations document "establishment" adequately, it is
submitted that the following should be irrelevant to the question of
establishment and treatment as an introduced species by SACC: that individuals
are found in urban areas (city parks with lakes); that birds are relatively
tame; that some birds are leucistic; that birds may be descendants of domestic
populations. The BOU place such species in "Category C4" and treat
them as introduced. Conversely, if northern South American birds are wanderers
from populations in Central America or the Caribbean, they should also be added
to the main list (= BOU "Category C5"). Columba livia is
affected by all these issues and is treated as an introduced species by SACC.
Persons looking for a reason to vote no on this one might point to
the lack of a population study and the recent nature of many records meaning
that they collectively do not evidence establishment. My personal view is that
the records above are of such a nature to tip the balance in favour of
inclusion on the main list.
Literature Cited:
Salaman,
P., Bayly, N., Burridge, R., Grantham, M., Gurney, M., Quevedo, A., Urueña,
L.E. & Donegan, T. 2008. Sixteen bird species new for Colombia.
Conservacion Colombiana 5: 80-85.
Other references are cited in Salaman et al. (2008).
Thomas
Donegan, May 2007
________________________________________________________________________________________________________
Comments from Stiles: "NO. What bothers me on
these two (i.e., #353) is just what the evidence is for considering these two
species really "feral" and "established". True, individuals
of some introduced populations in parks or fincas may nest without human
assistance - but does this really constitute the establishment of feral
populations? I have never seen mallards (or geese - and here one must specify
what species as there are several present in at least Colombian parks and
fincas) nesting away from humans or independent of humans for at least much of
their food and protection, etc. So, I'd like more information before approving
these proposals."
Comments from Stotz: "NO. We do not have clearly
defined rationale for treating species as established introductions, which is a
problem that it doesn't seem like the committee can get to worked up about.
Some of the birds that we consider established maybe should be reconsidered,
but at least these species don't have free-flying domesticated birds to contend
with. In the case of waterfowl, the presence of individuals in the wild seems
particularly uninformative about the status of those populations. I have seen
dozens of species of waterfowl in North America, which represent unestablished
exotic populations. Distinguishing between these birds and true vagrants is one
of the main activities of records committees in many states. The most similar
case to Mallard in South America is Muscovy in North America (excluding wild
vagrants in south Texas). It is considered established in the wild in Florida
by Robinson and Woolfenden, but AOU has not accepted that as a wild population
to this point. For Mallards in South America, there are no data on breeding
that leads to the conclusion that any of these populations are self-sustaining.
In the absence of that I don't see how we can seriously consider Mallard as an
established exotic."
Additional comments from Donegan: "Whilst I have sympathy for some of Gary Stiles' and Doug Stotz's
general points about escaped waterfowl and introduced domestic species, I am
not sure how relevant they are here. There are lots of escaped waterfowl
species that one sees from time to time. However, most of these are
singletons or small numbers and individuals/populations die out quickly.
The Bogota Mallard population can be traced back until at least 1992 (Ordonez'
"Aves del Jardin Botainco" by Ordonez mentions the species) - and
possibly before - and still goes strong 16 years on. The species is now present
and resident in at least three city parks with lakes in Bogota. The population
is not to my knowledge actively managed or subject to reintroductions to
maintain populations. The population in Parque Timiza is of particular
interest as the species has colonised and established itself there within
a matter of a couple of years at most. There, birds feed on grasses and algae as well
as human hand-outs. The Mallard has cosmopolitan feeding habitats and
has a track record of establishing introduced populations in other parts of the
world. If an introduced species breeds outside of pens and without active
human management, it is better included on lists and in field guides so that
people know what species they are observing. Indeed, much as we may not like
it, many city-dwelling folk in South America are more likely to see and want to
identify Anas platyrhynchos than, say, a rare
woodcreeper."
Comments solicited from
Robin Woods: "My information
on this species in the Falklands was summarised in my 1988 book and again in
the 1997 Atlas. I was quoting from Cawkell & Hamilton (Ibis 1961,
103a:12) who stated that some were released in East Falkland in the 1930's
'and are said now to be breeding in very small numbers.' I now know that
Rollo Beck reported a female Mallard with a white Pekin duck at Johnson's
Harbour a few miles east of Port Louis, East Falkland, on 5 November 1915 (ms
typed copy examined at AMNH New York) and that he saw a pair of Mallard that
landed by a kitchen door. The cook at the time reported that they brought
young to the house and when able to fly, went to nearby ponds.
"I have had no evidence in the past 50
years that Mallard still exist in the Port Louis area. However, in Stanley and
at Pebble Island within the past year I have seen domesticated ducks with
obvious traces of Mallard ancestry, that clearly were unable to fly. In
conclusion, I would say that the reference to naturalised Mallard in the
Falklands should be disregarded as I have seen no evidence of free-living
or breeding Mallard since 1956.
"The Mallard is not naturalised in the
Falklands though the species was introduced almost a century ago and it is
probable that some of their genes remain within groups of domesticated ducks at
a few settlements."
Comments from Jaramillo: "NO - I would require
knowing at an introduced and established population fit various criteria. One
of them is that it is breeding and self-sustaining for a minimum of 10 years
and I think this is probably not conservative enough. I also need to know that
the population is sizeable, hundreds of birds at least, and stable in
population or growing. I don't think that the Colombia population fits the
bill. Are there known nests? Are we sure that the population is not being aided
by further introductions by duck fanciers? The actual data on population size
is also unclear, and not to the level one needs to make this assessment. There
are plenty of introduced parrot/parakeet populations in North America for
example which are not yet considered established even though they fit more of
the criteria noted above than these Colombian Mallard populations. I would
rather hold off until better information is available on population numbers and
stability or increases over time.
"I have seen Mallards in Chile; I have also seen Mandarin
Ducks in Chile including juveniles! I have looked at various photos of other
Mallards from Chile some that look like wild types, others that have domestic
genes (largely Rouan breed, the big one with the high back end). Some of these
likely breed in the country, but they are far from being anything that I would
consider nearing an established population."
Comments from Cadena: "NO for reasons given by
Gary, Doug, and Alvaro."
Comments from Remsen: "NO, pending data on
stability, independence, and establishment of any feral population."
Comments from Robbins: "NO. There is no evidence to
indicate that there are self-sustaining populations for a prolonged (many
years) period of time."
Comments from Nores: "NO. Me parece que no hay casos documentados de individuos asilvestrados
nidificando libremente. Mallards hay por todos lados, incluso en plumaje
similar al de la especie original, pero siempre parecen estar relacionados con
los humanos. Además, el comentario de Robin Woods elimina el más fuerte de los
fundamentos para considerar la especie establecida. El caso de Columba livia es
muy diferente. En Argentina hay poblaciones ferales nidificando en cavidades en
barrancos ("cliffs"), en zonas bastantes alejadas de poblaciones
humanas."
Comments from Pacheco: "NO. Evidências incontestes acerca de uma estabilidade e do
estabelecimento de uma população feral na área da SACC parecem ainda faltar."