Long Skimmer (Orthetrum trinacria)

The photo above (by Diana Russell) can be viewed in OdonataMAP here.

Find this species in the FBIS database (Freshwater Biodiversity Information System) here.

Family Libellulidae

Orthetrum trinacriaLONG SKIMMER

Identification

Large size

Length up to 67mm; Wingspan attains 82mm.

The male Orthetrum trinacria is unlikely to be mistaken for another species. The combination of its size, shape and darker colour render it unmistakable.

Females are also readily identifiable and they have the distinct shape of the males but are overall pale yellow, boldly marked with black. Females and immature males can resemble those of Orthetrum icteromelas (Spectacled Skimmer) in terms of colouration and patterning. The Spectacled Skimmer is significantly smaller and there is no size overlap between the two species.

Click here for more details on identification.

Orthetrum trinacria – Male
Mpempe Pan, KwaZulu-Natal
Photo by Ryan Tippett
Orthetrum trinacria – Female
Falsebay, iSimangaliso Wetland Park, KwaZulu-Natal
Photo by Ryan Tippett

Habitat

Most often found around the fringes of still, open water habitats like lakes, pools and dams. Less regular at the margins of rivers and streams, where it favours slower moving sections. Occurs over a range of habitats throughout South Africa, including arid and semi-arid areas. Makes use of seasonal wetlands as well as artificial reservoirs and livestock drinking sites in the arid interior.

Habitat – Near Hluhluwe, KwaZulu-Natal
Photo by Ryan Tippett

Behaviour

Most often seen perched on vegetation over or near the waters edge. Also regularly sits on bare sand, gravel or rocks. Hunts from a perch and the flight is swift and typically low over the water.

A voracious predator that regularly feeds on large insects like butterflies and other dragonflies.

On the wing from October to May, although most common in late summer.

Status and Conservation

Common over large areas of South Africa. Listed as of Least Concern in the IUCN Red List of Threatened Species.

Distribution

Orthetrum trinacria is a very widespread species, occurring throughout Africa and is also found in parts of Southern Europe and the Middle East.

Occurs all over South Africa, although less numerous in the central, drier regions.

Below is a map showing the distribution of records for Long Skimmer in the OdonataMAP database as at February 2020.

The next map below is an imputed map, produced by an interpolation algorithm, which attempts to generate a full distribution map from the partial information in the map above. This map will be improved by the submission of records to the OdonataMAP section of the Virtual Museum.

Ultimately, we will produce a series of maps for all the odonata species in the region. The current algorithm is a new algorithm. The objective is mainly to produce “smoothed” maps that could go into a field guide for odonata. This basic version of the algorithm (as mapped above) does not make use of “explanatory variables” (e.g. altitude, terrain roughness, presence of freshwater — we will be producing maps that take these variables into account soon). Currently, it only makes use of the OdonataMAP records for the species being mapped, as well as all the other records of all other species. The basic maps are “optimistic” and will generally show ranges to be larger than what they probably are.

These maps use the data in the OdonataMAP section of the Virtual Museum, and also the database assembled by the previous JRS funded project, which was led by Professor Michael Samways and Dr KD Dijkstra.

Dragonfly Atlas: Megan Loftie-Eaton, Sally Hofmeyr, Ryan Tippett & Les Underhill
Dragonfly Atlas: Megan Loftie-Eaton, Sally Hofmeyr, Ryan Tippett & Les Underhill
Megan Loftie-Eaton is our communications, social media and citizen science coordinator. Prior to her work for the BDI, she coordinated OdonataMAP, the Atlas of African Odonata. Sally Hofmeyr has many years' experience in the academic world, writing her own material and editing the work of others. Her academic background is in the natural sciences: her PhD and first postdoc in ornithology and environmental change (Animal Demography Unit, University of Cape Town). Ryan Tippett is an enthusiastic contributor to Citizen Science and has added many important and interesting records of fauna and flora. He has been a member of the VMU since 2014 and has currently submitted over 11000 records. He is also on the expert identification panel for the Odonata Map project. Prof Les Underhill has been Director of the Animal Demography Unit (ADU) at the University of Cape Town since it started in 1991. Although citizen science in biology is Les’s passion, his academic background is in mathematical statistics.