Norfolk Hawker
Aeshna isoceles
The Norfolk Hawker is a distinctive dragonfly characterized by its entirely brown body, lacking the typical blue or green mosaic patterns of its relatives. Its most defining feature is a yellow, wedge-shaped mark on the second abdominal segment, which gives it its German name. It possesses striking green eyes, distinguishing it from the similarly colored Brown Hawker. This species is closely associated with nutrient-poor to mesotrophic standing waters, often occurring in habitats featuring the Water Soldier (Stratiotes aloides).
Details
Identification
Brown body, green eyes, yellow wedge on S2, clear wings with small basal tinting.
Social behavior
Solitary; males defend small territories along the shoreline against conspecifics.
Diet
Larvae feed on aquatic invertebrates; adults hunt flying insects such as mosquitoes, flies, and smaller dragonflies.
Hunting strategy
Active flight hunter that catches prey in the air or launches from perches.
Spawning substrate
Plant tissue of living aquatic plants, especially Water Soldier (Stratiotes aloides).
Overwintering
Overwintering occurs in the larval stage at the bottom of the water body.
Ecology
Ecological role
Important predator for controlling insect populations in both aquatic and terrestrial environments.
Natural predators
Birds (e.g., Eurasian Hobby), larger dragonfly species, fish and amphibians (for larvae).
Competitor species
Other large dragonflies such as the Southern Hawker or the Brown Hawker.
Ecosystem service
Biological pest control by consuming mosquitoes and horseflies.
Threats
Destruction of wetlands, eutrophication of water bodies, and decline of the Water Soldier plant.
Scientific profile
Profile
Distinguishing features
The most important feature is the combination of green eyes and a brown body. The eponymous yellow wedge spot on S2 is sharply defined. Unlike other hawkers, blue or green markings on the abdomen are almost entirely absent. The sides of the thorax show two yellowish longitudinal stripes.
Role in food web
Important predator in aquatic and terrestrial food webs; regulates insect populations.
Protection & threats
Main threats
Loss of reed beds due to shore stabilization, intensive water body maintenance (weed removal), eutrophication, and the disappearance of the water soldier (Stratiotes aloides).
Population trend
Increasing; the species is currently benefiting from global warming and is expanding its range northwards in Central Europe.
Conservation measures
Protection and promotion of reed zones, preservation of water soldier populations, avoidance of radical weed removal in ditches.