The Importance of Ivy

The Jersey Biodiversity Centre is working with our partners at the Pollinator Project JE and Jersey Trees for Life to publicise the importance of Ivy in Jersey's environment.

Mature ivy can provide a roosting site for bats, it's autumn flowers provide an important source of food for insects at this otherwise barren time of year and later in the season it's berries are a food resource for many different species of birds. 

We would be most grateful if you could record sightings of mature ivy (distinguishable by its flowers or berries) via our website or via the iRecord App.

It should be emphasised that ivy does not harm trees, and in most circumstances it should be left alone.  However, should you wish to prune ivy, then Jersey Trees for Life have produced this wonderful poster which shows how to do it in the most sensitive way.

Tim Ransom, the chair of the Societe Jersiaise Entomology Section has written a wonderful article about the importance of Ivy, which we have copied below.

We look forward to receiving your ivy sightings!

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THE IMPORTANCE OF IVY by Tim Ransom

Ivy is, arguably, the most important flowering plant for pollinators in the autumn which is at a time when there is often less on offer for them to feed on.  Many late-flying pollinators depend heavily on Ivy for pollen and nectar at this time of year.

Ivy (Hedera helix spp hibernica) is a native evergreen plant which is widespread and common across Jersey. Their flowers appear between early September to early November.

Figure 1, Ivy (Hedera helix) in flower, photo Tim Ransom

As well as their flowers being vital in the autumn for many insect pollinators, their berries, which ripen in winter, are a very valuable food source for overwintering birds such as blackbirds and thrushes and they are largely responsible for dispersing the seeds which produce more plants elsewhere.

Ivy is also an important winter hibernation site for many insects due to its dense foliage.

Ivy is vital to a wide variety of native pollinators such as hoverflies, butterflies, flies, wasps, solitary bees and bumblebees with, for instance, as many as 140 different insect species feeding on Ivy in the autumn including many overwintering queen bumblebees which rely on this plant to help them survive the winter and also 89% of pollen collected by honeybees in autumn comes from Ivy.

Figure 2. Red Admiral butterfly (Vanessa atalanta), photo Tim Ransom

Both the plant and the insects benefit greatly from this close relationship between them and it is the extensive mix of species that use Ivy in the autumn that not only ensures the continuity of such food sources from year to year but also helps to ensure their own winter survival, or of their young, to the following year.

One example of this reliance on Ivy is from the Ivy Bee (Colletes hederae) which emerges just as the flowers appear on their preferred plant, and at the height of their numbers they can be seen in their thousands feeding on Ivy across Jersey.

The Ivy Bee is a harmless solitary nesting bee which is heavily dependent on Ivy in order to raise their next generation. Each bee will excavate a single burrow nest, which can be up to 2 feet long, usually in coastal soft cliff soils where they lay their eggs.

This 1cm long bee has been spreading northwards naturally across Europe, due to climate change, and was first recorded in Jersey in 2001 and is now a very common species in the autumn and is one of the few solitary bees that will be seen regularly from September onwards.

Figure 3. Ivy Bee (Colletes hederae), photo Tim Ransom

Ivy takes around 10 years of growing before it is able to flower and so for them to be available to pollinators then they must be left to grow for at least this amount of time.

Often the Ivy seen growing in gardens, amongst flower borders and up trees, is the juvenile form of the plant and has lobed glossy leaves with no flowers but it is this plant that will eventually provide vital food sources for pollinators if allowed to grow until it matures and its leaves become an oval shape and it flowers.

So, given that this plant is so vital to many pollinators as a late-flowering food source enabling them, or their young, to survive the winter and that it also gives excellent winter protection to many other species it is very important that if you do have Ivy in your garden and up your trees then please do resist cutting it down!

Despite the common myth, Ivy does not kill trees. It has its own root system so does not tap into the tree’s vital resources. It only uses trees in order to climb higher to get maximum sun exposure for photosynthesis. But if Ivy appears to be swamping trees, and it is getting into their leaf canopy where it can affect the tree’s own ability to photosynthesize, then it can be thinned out, or reduced, but this should be kept to a minimum as complete removal does much more harm than good for insects and other wildlife.

And when checking out Ivy and you see any insects feeding on it, and especially pollinators, then it would be very useful to submit these records to the local records database at the Jersey Biodiversity Centre website (or alternatively via the iRecord app), preferably with a photo, as this will not only show which species are using Ivy locally but also, and importantly, where those areas are which pollinators are using as vital food sources in the autumn.
           
Ivy is a great plant to get out and about looking for insects on in the autumn, in both urban and rural areas, and you will be surprised at how many insects, and how many different types, are to be seen feeding on it.

It is truly a 5-star restaurant for pollinators!