Friday, October 15, 2010

Red Squirrels Have Come Back Before

Red Squirrel, Sciurus vulgaris
The Red Squirrel (Sciurus vulgaris) is the only native Irish squirrel and is easily recognisable by its orange-red fur and distinctive ear tufts. Its body is 20-28 cm in length and its tail is usually paler than its body (Sterry, 2004 Collins Complete Guide to Irish Wildlife p. 20). Its decline in Ireland in recent years has been well documented in the popular press. The most recent survey of S. vulgaris numbers by Carey et al. in 2007 showed no individuals in counties Meath or Westmeath and only a few records from Louth, Carlow and Kilkenny combined (The Irish Squirrel Survey 2007, COFORD). It is estimated that there are currently 40,000 individuals in the whole of Ireland (2008, National Parks and Wildlife and Environment and Heritage Service of Northern Ireland, All-Ireland Species Action Plan: Red Squirrel).

This decline has been blamed on the spread of the Grey Squirrel (S. carolinensis), a species introduced from America to Castle Forbes in Co. Longford in 1911. S. carolinensis is a larger animal than S. vulgaris (body length 25-30cm) and this, along with their wider dietary range allows them to outcompete the Red Squirrel. Woodland availability and woodland species composition also have an effect on S. vulagris numbers.

Yet S. vulgaris has experienced all of this before. In 16th century Ireland, a large part of the native woodlands were cleared, which possibly lead to the extinction of S. vulgaris. In the 1800s, individuals were translocated from Britain to Ireland, thus reintroducing the species (Barrington, 1880 Scientific Proceedings of the Royal Dublin Society 2 pp. 615-631). In 2003, 19 S. vulgaris individuals were successfully translocated to Derryclare, Connemara in western Galway, which prompted a further translocation of individuals to Belleck Forest Park in Co. Mayo (Finnegan, 2007 The Translocation of Red Squirrel (Sciurus vulgaris) to Belleek Forest Park, Mayo – Phase One).

Thursday, October 14, 2010

The Shaggy Ink Cap is a Nematophage

Shaggy Ink Cap, Coprinus comatus
The Shaggy Ink Cap (or Lawyer's Wig, Coprinus comatus) is a large, gregarious basidiomycote fungus that is often collected from the wild and eaten. The fruiting body first appears as an oval structure with no visible stem. The cap is covered with shaggy pale white to brown scales. It pulls away from the stem, turning pink, then black. The cap then dissolves into a black ink-like fluid (Harding et al., 1996 How to Identify Edible Mushrooms p. 54).

Shaggy Ink Cap, Coprinus comatus with cap dissolving
C. comatus was assumed to be an excusively saphrophitic fungus. However, Luo et al. (2004 Mycologia 96 pp. 1218-1224) report on trapping, killing and feeding on two nematode species, the free living Panagrellus redivivus and the root-knot nematode, Meloidogyne arenaria by the fungus. It produces burr-like structures on sporophore-like branches called spiny balls that damage the nematode cuticle leading to leakage of the inner materials of nematodes (Luo et al., 2007 Applied and Environmental Microbiology 73 p. 3916-3923). In addition, C. comatus produces toxins that immobilise the nematodes. Once a nematode has been infected, it is digested and consumed within days. Hyphae then grow out of the nematode.

Wednesday, October 13, 2010

Enchantingly Perennial

Enchanter's Nightshade, Circaea lutetiana
Enchanter's Nightshade (Circaea lutetiana) is a delicate herb of damp woods, shady places and hedgerows on basic soil (Phillips, 1977 Wild Flowers of Britain p. 90). It has opposite pairs of oval leaves and bears flowers in loose spikes above the leaves. It exhibits a pseudo-annual life cycle: it is a perennial (clonal) plant that behaves as a vegetatively propagating annual (Verberg and During,  Plant Ecology 134 pp. 211-224). C. lutetiana completes its life cycle at the end of the summer, producing seeds or hibernacles from the rhizome apices. These hibernacles do not produce new ramets and remain dormant over winter, giving rise to new vegetative growth in the spring.

Tuesday, October 12, 2010

We Only Come Out at Night

Millipedes are important detritivors in most ecosystems as they promote the decomposition of dead plant material, thus stimulating microbial growth. Ingested leaf litter is particulated in the millipede gut, meaning that when egested as faeces more surface area is available for bacterial and fungal colonisation (Hopkin and Read, 1992 The Biology of Millipedes p. 4).
Tachypodoiulus niger
Two of the most common species of millipede found in Ireland are Tachypodoiulus niger and  Polydesmus angustus. T. niger is commonly known for its tendency to curl up like a spring when disturbed. It is often found under tree barks (Chinery, 1987 Field Guide to the Wildlife of Britain and Europe p. 275). P. angustus has a flattened body (earning it the common name Flat-Backed Millipede) and resembles a centipede, but its two pairs of legs per segment identifies it as a millipede (Sterry, 2004 Collins Complete Guide to Irish Wildlife p. 172).
Polydesmus angustus
Both of these species are quite numerous, for example making up to 50% of the April diet of starlings (Lindsey, 1939 The Wilson Bulletin 51 pp. 176-182), but are often inconspicuous due in part to their presence in leaf litter but also because they tend to be nocturnal animals. Banerjee (1967, Oikos 18 pp. 141-144) observed that both species are most active during darkness from one hour after sunset till one hour before sunrise. Activity extends into the afternoon in the summer months.