Coleoptera (beetles)

The coleopterans represent about 40% of insect species. They occupy every imaginable habitat. They are distinguished by their two very different pairs of wings. The outermost pair of wings, the elytra, form a hard carapace over the inner wings, which are more delicate and adapted for flight.

A study made after the 1998 ice storm investigated the possibility that the abundance of wood- and sap-feeding beetles might provide good bioindicators of the present and future health of the forest. In the aftermath of the ice storm insect populations increased, and the wood-feeding insects became relatively more abundant. Fully 69% of the insects collected fed on wood, only 11% on plant or animal materials. A total of 69 insect species were collected in this fairly brief survey, of which 17 were found only at Mont St. Hilaire, among many sites in southern Quebec.

Partial list of colleoptera on Mont St. Hilaire [.pdf]

Diptera (flies)

The dipterans are another large, widely distributed order of insects. They have only a single pair of wings, and a wide diversity of mouth parts adapted to different feeding strategies.

Partial list of dipterans on Mont St. Hilaire [.pdf]


Aphids feed exclusively on the sap of plants, each species often feeding only on a particular plant host. A preliminary study identified 59 species of aphids on Mont St. Hilaire, some of them considered rare.

Partial list of aphids on Mont St. Hilaire [.pdf]


Collembolans are tiny insects that are very numerous in soil. They feed on the hyphae of fungi and on decomposing organic material in soil. Some possess a very peculiar organ, the furcula, that allows them to jump astonishingly high for their size. A recent study found 27 species of collembolans at Mont St. Hilaire, one of which was entirely new to science.

List of the collembolans of Mont St. Hilaire [.pdf]

Lepidopterans (butterflies and moths)

Louis Handfield, a resident of Mont-Saint-Hilaire and an amateur lepidopterist, has collected lepidopterans on and around the mountain for over 30 years. His exceptional efforts have found over 800 species of butterflies and moths associated with the mountain and its surroundings. This high level of diversity arises from the physiographic diversity of the region and the high diversity of food plants. Fully 130 species are rare or of restricted distribution.

List of the macrolepidopterans on and around Mont St. Hilaire [.pdf]

For more info, please consult:

Handfield, L. et al. 1999. Le guide des papillons du Québec, version scientifique. Broquet, Canada, 536 p.



Lac Hertel contains only 8 species of fish, probably because of its small size and shallow depth. Contrary to popular opinion, the lake has an average depth of only 5 metres and its deepest point is only 9 metres.


Reptiles and amphibians

There are four species of salamanders, eight frogs, two snakes and a turtle found at Mont St. Hilaire.

List of reptiles and amphibians at Mont St. Hilaire [.pdf]

Although the site is well protected, the populations of reptiles and amphibians are vulnerable to disturbance. The amphibians are especially sensitive to pollution or reduction of their preferred habitats. The dusky salamander (Desmognathus fuscus) and the western chorus frog (Pseudacris triseriata), which had occurred on the mountain in the 1960s, are now gone. Because of their popularity as pets, the reptiles and amphibians are also threatened by illegal collection. It is much better to observe these organisms in their natural habitat than in captivity!


In spring and fall Mont St. Hilaire welcomes many migrating bird species in addition to those that reside on the mountain in other seasons. Various waterfowl rest on Lac Hertel in fall and the woods are full of warblers for a few days each spring. More than 200 species of birds have been seen on and around the mountain.

List of birds observed at Mont St. Hilaire [.pdf]

Probably the most striking birds at Mont St. Hilaire are the peregrine falcons nesting on the Dieppe Cliffs. This is an endangered and protected species with only ten natural nesting sites known in Quebec. The species is especially disturbed by human activity near its nesting site, which is why we forbid access to the cliffs at Mont St. Hilaire.



The most frequently observed mammals at Mont St. Hilaire are chipmunks, squirrels, raccoons and porcupines. The old-growth forests and sheltered lakeshore provide habitats for other more reclusive species. Some are active mostly at night and others avoid human contact.

List of the mammals of Mont St. Hilaire [.pdf]

In some years there are unexpected, usually occasional visitors to the mountain. In 1999, a lynx was on the mountain but there was no sure sign of its presence the next year. That same year a female moose spent a month or so on the mountain but then moved on. It is possible the lynx is still on the mountain but using only the Preservation Sector, which is visited only rarely by a few researchers monitoring permanent study plots. This species, which is considered for listing as endangered, would be a welcome addition to the fauna of Mont St. Hilaire.