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:

 

"FjeldsĆ & 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., UrueĖa, 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

 

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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. Evidźncias incontestes acerca de uma estabilidade e do estabelecimento de uma populaćčo feral na área da SACC parecem ainda faltar."