love and war in your garden
Members of the Gardeners’ Club were treated to a fascinating illustrated talk by Alick Jones on love and violence between, and within, species in our gardens. The familiar robin will defend its territory vigorously and even attack red balls of wool! The cuckoo leaves other birds to bring up its young which, once fledged, take their first long flight to overwinter in the Congo. The female dunnock (hedge sparrow) will often mate with an alpha and beta (younger) male if their territories both overlap hers and all three birds will then feed the young, of which only 1/5th will be the beta’s offspring. Breeding times for blue tits coincide with the prevalence of moth caterpillars in oak trees. A 10.5 gm bird lays an average of 8 eggs at 1 gm each and a chick eats 100 caterpillars per day. Their lifespan is 3 years although exhaustion can result in many not surviving the winter.
Grass snakes prefer rotting vegetation, such as compost heaps, to lay their eggs, which require a temperature of at least 21 oC, preferably 28 oC, to survive and hatch. They are strong swimmers, can be found close to fresh water—pond edges are favoured—and their diet consists mainly of frogs, toads and newts. Dragonfly larvae spend several years underwater and feed on sticklebacks and small newts. The adults live for only a few days or weeks and catch other insects on the wing.
Plants utilise insects in different ways. Naturalised populations of Sarracenia, the North American pitcher plant, can be found in Ireland and the Lake District. These attract insects with nectar around the rim of the pitcher opening and waxy scales cause them to lose their footing and tumble into the depths of the plant. Digestive fluids then extract nutrients from the insect. The Cuckoo Pint, Arum maculatum, is a common woodland plant that enslaves insects. The flowers are hidden from sight with a ring of male flowers above a ring of female ones. Above the former is a ring of hairs that temporarily trap an insect so that it is dusted with pollen by the male flowers before escaping and carrying the pollen to other plants where it pollinates the female flowers. Beware of the cluster of bright red berries on the plant in autumn as they are extremely poisonous.
Hoverflies are recognised as an important natural enemy of pests as well as pollinators. They are particularly attracted to the hardy shrub, Deutzia where their larvae eat aphids and pollinate the plant in the process. Finally, Alick mentioned a recent RSPB report estimating that the UK’s 8 million cats are ‘known’ to catch an estimated 275 million prey items a year, of which 55 million are birds. However, many millions of birds die naturally every year and there is no scientific evidence that cats have an impact on bird populations. Furthermore, there is evidence that cats tend to take weak or sickly birds.