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Friend or foe? Madagascar Turtle Doves (Nesoenas picturatus) on Mauritius

Johannes Fischer

Mauritius has suffered a severe reduction of its native flora and fauna, with several bird species driven to extinction, including the world famous Dodo (Raphus cucullatus). Most, if not all, of these losses of biodiversity can be attributed to introduced species and habitat loss. (Cheke and Hume 2008) One of these introduced species is the Madagascar Turtle Dove (Nesoenas picturatus), which is currently recognised as native on islands of the Western Indian Ocean belonging to the countries of Madagascar, Comoros and Seychelles (Baptista et al. 1997). The nominate subspecies from Madagascar is assumed to be introduced to the Mascarene Islands, including Mauritius (see figure 1), but any specifics or dates of these introductions are lacking (Baptista et al. 1997, Sinclair and Langrand 2003, Cheke and Hume 2008).

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Figure 1. Madagascar Turtle Dove (Nesoenas picturatus picturatus) caught at Black River National Park, Mauritius, Indian Ocean. Franky Gamble.

 

The Pink Pigeon (N. mayeri), a sister species to N. picturatus (Johnson et al. 2001) and an endemic to Mauritius, is classified as Endangered (IUCN 2015). A recent study has shown that N. mayeri might suffer from “signal-jamming” by N. picturatus, as their territorial calls are similar, meaning that N. mayeri might waste time and energy responding to the territorial calls of N. picturatus. (Wolfenden et al. 2015). Swinnerton et al. (2005) also showed that N. picturatus can act as disease vectors on Mauritius, causing complications for N. mayeri. Wolfenden et al. (2015) argue that these two factors may impede N. mayeri from recolonizing Mauritius.

Even though the slow recolonisation of Mauritius by N. mayeri might be partially attributed to the presence of N. picturatus on Mauritius (Wolfenden et al. 2015), it has to be noted that other introduced Columbids such as Rock Dove (Columba livia), Eastern Spotted Dove (Spilopelia chinensis) and Zebra Dove (Geopelia striata) also occur on Mauritius (del Hoyo et al. 2015). These species may play an equally large part as N. picturatus in the spread of avian diseases. Furthermore, Wolfenden et al. (2015) documented that N. mayeri not only reacts to N. picturatus calls, but also to S. chinensis, thus also wasting a certain amount of time and energy on responding to S. chinensis. Therefore, it seems highly oversimplified to attribute the threatened status of N. mayeri solely to the presence of N. picturatus (Wolfenden et al. 2015), especially since the extent of intact native forest on Mauritius has been reduced to extremely tiny patches and several introduced mammalian predators roam the island (Cheke and Hume 2008).

Additionally Hume (2011) describes a new species of Nesoenas pigeon, N. cicur, from sub-fossil remains found on Mauritius. N. cicur was most likely a species endemic to Mauritius and probably became extinct as a result of overexploitation by early settlers, deforestation and predation by introduced species around 1730 AD (Birdlife International 2015). Naturally, little is known of the ecology of this extinct taxon but it might have resembled N. picturatus, although it was probably more terrestrial (Birdlife International 2015).

Considering these putative similarities between the extinct taxon, N. cicur and the, presumably, introduced taxon, N. picturatus, the argumentation of N. picturatus filling the niche of N. cicur seems self-evident. Furthermore, recent discussions on introduced species have argued that introduced does not automatically mean harmful and that introduced species are most certainly capable of providing useful services, even to the extent of achieving conservation and restoration goals (Marris 2011). There is a difference between an invasive and an introduced species. It seems unjustified to treat N. picturatus as an invasive and practice “pest” control to a certain extent to reduce numbers.

When directing the efforts of introduced species management, I suggest focusing energy and resources on other Columbid species introduced to Mauritius like C. liviaS. chinensis and G. striata, as they do not currently fill a native niche, as N. picturatus is likely to do. Instead of trying to eradicate N. picturatus, I recommend to embrace it as a close approximation of the extinct Mauritian native N. cicur and consider it an extension of the (very limited) extant fauna of the island.

References

Baptista, L.F., Trail, P.W. & Horblit, H.M. (1997). Madagascar Turtle-dove (Nesoenas picturatus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2014). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/54162 on 17 March 2015).

BirdLife International (2014) Data zone. Downloaded from http://www.birdlife.org on 17 March 2015.

Cheke, A., Hume, J.P. (2008) Lost Land of the Dodo: The Ecological Histry of Mauritius, Reunion and Rodrigues. Yale University. Press, New Haven, CT.

del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2015). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/ on 18 March 2015).

Hume, J.P. (2011) Systematics, morphology, and ecology of pigeons and doves (Aves: Columbidae) of the Mascarene Islands, with three new species. Zootaxa 3124: 1-62.

IUCN. (2015). The IUCN red list of threatened species. Version 2014.3. Retrieved on 17 March 2015, from http://www.iucnredlist.org.

Johnson, K. P., de Kort, S. R., Dinwoodey, K., Mateman, A. C., Lessells, C. M., & Clayton, D. H. (2001). A molecular phylogeny of the dove genera Streptopelia and Columba. Auk, 118(4), 874 – 887.

Marris, E. (2011) Rambunctious Garden: Saving Nature in a Post-wild World. Bloomsbury USA, New York.

Sinclair, I., and Langrand, O. (2003) Birds of the Indian Ocean Islands: Madagascar, Mauritius, Reunion, Rodrigues, Seychelles and the Comoros. Random House Struik.

Swinnerton, K. J., Greenwood, A. G., Chapman, R. E., & Jones, C. G. (2005). The incidence of the parasitic disease trichomoniasis and its treatment in reintroduced and wild Pink Pigeons Columba mayeri. Ibis, 147, 772-782.

Wolfenden, A.W., Jones, C.G., Tatayah, V., Zuel, N., & de Kort, S.R. (2015) Endangered pink pigeon treat calls of the ubiquitous Madagascan turtle dove as conspecific. Animal Behaviour 99: 83-88.