David Element's Wildlife Web Page Dragonflies and Damselflies 3

David Element

Wildlife Photography

and Digital Video Images

____________ Dragonflies and Damselflies 3

NORFOLK HAWKER Aeshna isosceles (f)

WHITE-FACED DRAGONFLY Leucorrhinia dubia (m)

FOUR-SPOTTED CHASER Libellula quadrimaculata (m)

The Norfolk Hawker is a significant rarity in Britain, confined to a small number of suitable fenland sites in East Anglia and just about holding its own (if not actually expanding its range) during a period of sympathetic management. On hot June days these dragonflies are most easily seen patrolling well above head height. The early flight period does not normally overlap with that of the Brown Hawker, the only possible confusion species (see Dragonflies and Damselflies 1 for comparison). The green eyes and the yellow triangle on the second abdominal segment are absent in this latter insect. The illustrated dragonfly flew right in front of the photographer as he was returning home after a long, hot and fruitless search and settled in a tree right beside the path, allowing a mixture of still and mini-DV images (captured still shown) to be taken. The conditions for photography were far from ideal with fierce natural backlighting making accurate exposure difficult. Another illustration may be seen on Dragonflies and Damselflies 5.

The White-Faced Dragonfly has recently become extinct in the south of England (c 1999) and this species appears to be retreating northwards in a possible response to a combination of Global Warming and habitat loss. It is a wet heathland specialist which always appears to have persisted at low population densities in Surrey where the individual shown above was photographed in 1989. There are still strong colonies in Scotland and north west England.

The Four-spotted Chaser, seen here as a captured mini-DV still, is one of the most widely distributed and common British dragonflies (favouring waters with acid pH) and there are no concerns about its conservation at present. It is an unusual 'chaser' in the sense that there is no obvious sexual dimorphism and the genitalia need to be examined to differentiate between the sexes. Fortunately the insects themselves don't have any problems in making this distinction! Males of the other chaser species develop a characteristic powdery blue 'pruinescence' as they mature. Male Four-spotted Chasers hold a territory with a particular perch as a focal point, often a stem projecting from the surface of the water. A rather beautiful variant, termed form praenubila, has extended black clouding on the wings. This species also has the doubtful distinction of being the only dragonfly which the photographer has seen being caught and eaten by a duck. A female Mallard was observed sneaking up behind a perching quadrimaculata and a few seconds later any pre-conceived ideas that a duck couldn't catch a dragonfly were suitably despatched, along with the unsuspecting victim!