Current distribution of Monarch Butterfly (Danaus plexippus) in mainland Portugal (2020)

Study Extent

The study extends throughout ~350 km2 of the southwest littoral belt, ~650 km2 of the western coastal Algarve, and ~350 km2 in central and eastern coastal Algarve, encompassing, from West to East, the municipalities of Odemira, Lagos, Portimão, Monchique, Lagoa, Silves and Faro).

Sampling

The areas where the butterfly’s presence was previously reported (Palma and Bívar de Sousa 2003) were surveyed by car at <40 km/h, carefully searching for host plants patches and/or flying monarchs along 992 km of paved and unpaved secondary roads. The search for plant patches was carried out in September-December 2017, September-October 2018, and July-October 2020, but the information on the Danaus presence was obtained only in the last period. At each patch detected, the identity of the hostplant species, its geographic coordinates and overall features regarding patch geometry and density (i.e., sparse or dense, linear or compact), as well as habitat type (i.e., riverbank, pasture fallow, field fence, road verge) were recorded. The number of plants per patch was counted directly (in patches up to ~50 plants), or visually estimated (in patches with more than 50 plants), by extrapolating the number4 counted in a small fraction of the area to the entire patch. Apparent threats, such as mechanical clearing, pasture conversion, competition by natural vegetation, were also recorded. In addition, patches of Lantana (Lantana camara), an ornamental alien plant widespread on chalet walls and in gardens, and along road verges throughout the Algarve, which are known to attract butterflies, including the monarchs (Fernández-Haeger and Jordano Barbudo 2009) were systematically watched for flying monarchs while driving.

Quality Control

All identifications were performed by qualified technicians

Method steps

1. To be completed

The taxonomic coverage of this dataset spans 1 phylum, 1 class, 1 order, 1 family, 1 genus and 1 species.

1. Chordata
   rank: phylum
2. Insecta
   rank: class
3. Lepidotera
   rank: order
4. Nimphalidae
   rank: family

The data were collected in Southwest and Southern areas of mainland Portugal, in the municipalities of Odemira, Portimão, Lagos, Silves, Faro, Lagoa and Monchique.