European Atlantic mixed forests

A Yellow-legged Hornet (Vespa velutina nigrithorax) was photographed on Henri Schoofslaan in Auderghem on September 8, a few streets from the edge of the Forêt de Soignes. It's the invasive Asian hornet known for preying on honeybees, and iNaturalist records show it turning up repeatedly across the wider Brussels region this year: well over a hundred sightings logged in the past twelve months alone, spanning communes from Auderghem, Ixelles and Watermael-Boitsfort to Tervuren, Wemmel and Leuven. That pattern of records doesn't establish population size or trend — sightings track observer effort as much as anything — but it does show the species is being found widely and repeatedly around the forest, not just this once.Telling it from the native European Hornet takes one look at the color. The European Hornet is a big yellow wasp with black bars and a reddish-brown head and thorax. The Yellow-legged Hornet is the reverse: velvet black or dark brown, each abdominal segment edged with a thin yellow line, a single broad orange band toward the tail, an orange face, and legs that end in bright yellow as if dipped in paint. It usually runs a little smaller. The yellow feet are the mark most people catch first.September is when its colonies are as large as they will get. A nest at this point holds a few thousand individuals, and the workers are provisioning larvae at full tilt. This is the month for the behavior beekeepers dread: workers hang in the air in front of a hive entrance, pick off single bees returning heavy with pollen, then cut away head, wings and legs and carry the thorax home. Honeybees are not the whole diet, though. Nests studied in southwest France took honeybees for about 38 percent of their prey, flies for about 30 percent and other social wasps for about 20 percent, with more than 150 prey species in all. Colonies near forest leaned harder on native wasps; colonies in town leaned on honeybees. A single nest can take roughly eleven kilograms of insects in a season, which is why the concern extends to native pollinators and not just to hives.The nest itself is usually invisible right now. A queen starts small in spring, low in a shrub or under a roof edge, and by summer the colony shifts to a large paper nest high in a tree canopy. In beech and oak stands like the Soignes those only show once the leaves drop in October and November, by which point the colony is already producing next year's queens. Workers and the old queen die with the cold. Only the mated young queens overwinter, each one capable of founding a new nest in spring.Brussels handles this through Bruxelles Environnement, which trains a referent in each commune to take sighting and nest reports. A hornet hovering at a hive, or a large grey nest appearing in a bare canopy this fall, is what to report.

A Eurasian Eagle-Owl was confirmed at De Schavuienhof, near Bierbeek, on August 17, verified across three separate reports by regional reviewers. In the past two weeks it was the only species flagged as notable anywhere within 25 kilometers of this stretch of Atlantic mixed forest, which says something about how far outside the ordinary checklist this bird sits.This is not a small owl passing through on a whim. Bubo bubo is Europe's largest owl species, a sedentary, territorial hunter with a wingspan that can top six feet, built to take prey up to the size of a young fox or a heron. It doesn't migrate; where it settles, it tends to hold ground for years, which is part of why a single confirmed sighting carries more weight than a stray songbird would. Hunting pushed the species out of much of lowland Western Europe by the mid-20th century, and it has spent recent decades recovering and pushing back into former range, helped in places by reintroduction projects and by protection of the nesting cliffs and old quarries it favors. A bird turning up in a Belgian forest like this one fits that pattern of recolonization far more plausibly than it fits the alternative explanation of an escaped falconry bird.What it would find if it stayed is worth a note of its own. This same forest holds a small, recurring population of Siberian Chipmunk, an Asian squirrel that has become established in patches of Belgian and French woodland after escaping or being released from captivity. Eagle-owls are generalist hunters that take rodents readily in exactly this kind of habitat, so the owl's arrival and the chipmunk's foothold here are worth watching as connected threads in the same patch of woods, even though nothing so far confirms one is preying on the other.

Confirmed, established populations of the Yellow-legged Hornet are turning up in and around the Sonian Forest on the edge of Brussels. Nineteen research-grade records came back from this stretch of the European Atlantic mixed forests ecoregion, running from late February through the first week of August and clustered across Watermael-Boitsfort, Auderghem, Woluwe and Groenendael on the Hoeilaart side of the forest. Two of them are identified all the way to Vespa velutina nigrithorax, the subspecies behind the European invasion. Every record is flagged introduced. That matters more here than it might elsewhere, in a forest that carries legal protection precisely because of the species that depend on it.This hornet is a different kind of concern from the seasonal sightings that usually fill a summer field note. It is not native to Europe, and the pattern here — repeat sightings at the same handful of sites, spanning most of a season rather than a single week — is what distinguishes a spreading population from a stray individual. It hunts. Workers station themselves outside honeybee hives and native bee nests, snatching foragers returning heavy with pollen, sometimes hovering at the entrance long enough over a season to strip a colony of its workforce. Native wasps and bees, which evolved without this predator in the picture, have no particular defense against it. A protected forest is exactly the kind of place where sustained predation pressure on pollinators carries the highest stakes.This is a presence record, not a population count. Observation counts reflect observer effort, not abundance. What the records do establish is that the hornet is here and persisting across the season, not just passing through, which is the threshold that usually triggers nest-search and removal efforts in affected regions. Anyone spending time in the Sonian Forest this season is worth asking to keep an eye out and report sightings, since early nest detection is the main lever available against this species once it's established.

A Common Hedgehog (Erinaceus europaeus) turned up in Forest on July 25 — an unverified record (needs_id) but the second sighting this summer, after a research-grade observation in June, and part of a scatter of four records across Brussels green spaces over the past two years.July is juvenile dispersal season: young from spring litters push out of their birth sites, crossing roads at dusk and moving between gardens and park margins to stake out new territory.The species has declined sharply across western Europe, squeezed by traffic, pesticide pressure on invertebrate prey, and the loss of rough, unmanaged ground for shelter. These sporadic sightings across the city's patchwork of gardens, churchyards, and small parks suggest some corridor of movement still exists — but four records over two years is a thin thread, and iNaturalist flags this species as threatened throughout the region.

Old World Swallowtail (Papilio machaon) has appeared twice in the city this summer — once at Laeken on July 15, again near Chapelle on June 27 — suggesting that breeding may now be underway in urban Brussels rather than merely passing through.Females of this species stay close to their egg-laying plants, and the appearance of two individuals weeks apart in midsummer is a strong signal of established populations. Wild carrot on railway margins and other ruderal edges has become an anchor for the species here; warmer summers are steadily expanding the range of its host plants northward, opening ecological doors that were shut just a decade ago.

Broad Scarlets (Crocothemis erythraea) — a dragonfly of Mediterranean origin — have become a fixture at Brussels ponds only in this past decade. Between July 1 and 9, ten individuals were logged patrolling the water margins, expanding their range northward alongside warming summer temperatures. Their arrival marks a shift in the region's dragonfly fauna.Vagrant Darters and Blue Emperors were hunting alongside them — a combination of odonates that would have been unthinkable in these waters a generation ago. The pond community is being reshaped by climate, and what once seemed like vagrant records are now becoming the established summer guild.

Four-lined Giant Mayfly (Ephemera glaucops) appeared on the wing at Friche Josaphat in late June—a striking recovery for a species that vanished from urban Brabant by mid-century. The nymphs are burrowing larvae that spend two full years in stream sediment before emerging, which means their return signals two years of water quality good enough to sustain them through development.Caenis mayflies (both C. horaria and C. robusta) appeared the same week downstream at Domaine des Silex, with smaller mayflies documented at La Hulpe by week's end. Nine mayfly records across 60 days and 20 kilometers is not a surge—but it is a quiet signal. These insects were absent long enough that their return, even at low numbers, marks a meaningful shift in stream ecology and chemistry in this urban corridor.

Norfolk Hawker dragonflies (Isoaeschna isoceles) have been active across the Sonian forest ponds for two consecutive summers now — 76 records logged at Auderghem, Woluwe-Saint-Pierre, and Hoeilaart between late May and late June. This is not a coincidence. The species has a strict ecological requirement: its larvae develop in water soldier beds, and they cannot tolerate polluted water. The larvae feed in the floating rosettes for years before emerging.Two straight years of sightings at the same sites signals a genuine if quiet recovery in these forest waters. The presence of water soldier and the hawkers that depend on it is a marker of improving water quality — the kind of signal that takes time to accumulate and is easily missed without patient, attentive watching over seasons.This is recovery worth noting in a region where freshwater dragonfly communities have been under long-term pressure from eutrophication and habitat loss.

Rose-ringed Parakeets (Psittacula krameri) are now breeding across the city—68 sightings since January span the entire metropolitan area, from the northwestern suburbs to Tervuren. These are birds that escaped from the pet trade over decades, establishing populations through incremental releases and cage breaks. Each pair competes fiercely with jackdaws for nesting cavities in mature park trees, creating a quiet but measurable conflict for the cavity-nesting guild.Yet the ecosystem is not surrendering entirely. A Common Hedgehog (Erinaceus europaeus) was logged in Woluwe-Saint-Pierre this week—a native mammal increasingly rare in the urban fabric. Its presence, threatened as it is, reminds us that the older ecology still holds a tenuous foothold in the margins between the invasive and the domesticated.

The oldest trees near Pentagone hold moisture long after the sun goes down. Bark loosens from decaying trunks, leaf litter mats into layers along the roots, and the soil beneath stays cool even on the longest days of early summer. This is the habitat a fire salamander needs: not water exactly, but the dampness that collects where wood rots and invertebrates shelter. After dark, when the temperature drops and humidity rises, these animals move through it slowly and deliberately, working the ground with their tongues.Fire salamanders are not fast hunters. They are patient ones. A salamander will press itself close to a rotting log, tongue flicking to detect chemical traces left by earthworms, slugs, woodlice, and beetle larvae buried in the soft wood. The tongue strike itself is quick, but the approach is not. They cover ground methodically, quartering damp patches the way a dog works a scent trail, returning to productive spots on successive nights. Early summer is a critical feeding window for them. Females in particular are building reserves, because fire salamanders give birth to live larvae, small aquatic young that they carry internally until the larvae are ready to be deposited in a stream or seep. That investment is metabolically expensive, and the richness of summer invertebrate life in the leaf litter is what makes it possible.The spotted longhorn beetle connects to this indirectly, and the connection runs through the same rotting wood. Spotted longhorn beetles are flower visitors as adults, conspicuous in early summer on hogweed and bramble, but their larvae develop inside dead and dying hardwood, feeding on the decaying tissue for one to three years before emerging. The frass and soft galleries they leave behind create exactly the loose, moisture-retaining substrate that concentrates the smaller invertebrates a fire salamander hunts. A beetle larva in its gallery is also, occasionally, prey itself. Salamanders are not selective in the way a specialist predator is. If something soft-bodied and slow is present in the wood, and the salamander encounters it, it will eat it. The beetle's larval stage and the salamander's hunting range overlap in the same decomposing wood, and what the beetle larva modifies in the wood, the salamander's other prey then colonizes.The fire salamander is a threatened species here. Its presence near Pentagone depends on two things that urban green spaces often lack: standing deadwood left in place, and a water source close enough for larvae to be deposited. The European stag beetle, also recorded in this area and also threatened, shares the dependence on deadwood. Both species are indicators of something the site is doing right, that some of the old wood is being left to decay rather than cleared. The Asian lady beetle, an invasive species now abundant here, competes with native invertebrates for aphid prey and disrupts the food web at the smaller end, but its effect on the specific community of woodlice, worms, and beetle larvae that salamanders rely on is less direct.On a warm night in early summer, a salamander moving through the litter near a damp log is visible if you look slowly. The yellow and black patterning is not camouflage. It is a warning, advertising the toxic skin secretions the animal produces. Predators that have encountered one before avoid them. The pattern works because it is memorable, and it is memorable because it is so distinct: broad irregular patches of yellow against black, varying between individuals, consistent enough as a signal to be recognized. If you are out after dark near any of the older, damper tree stands at Pentagone, you might crouch beside a mossy log and wait. The salamander will come to you before you find it. Right now the ground is cool and damp beneath the canopy, and somewhere in that darkness a tongue is already working.