Tayside's Batty Graveyards

In the summer of 2018 Jean Oudney, a TBG member, completed a university honours research project looking at bat activity in some of the graveyards and cemeteries in Tayside.

At present, there is no information and no advice available to owners and managers on what bats use the Tayside graveyards and cemeteries, which elements are important to the bats and how to protect and enhance these features.

This project looked to establish which species were present, and looked at their activity levels in relation to different features of the graveyards and the surrounding landscape in order to assess which features could be recommended as benefiting the local bat populations.

Why graveyards?

Although graveyards are relatively small areas they can hold proportionally more diversity of plant and animal life than surrounding areas, especially in intensive arable farmland or urban areas where they have more quality and variety of vegetation. They can also be protected by their walls, trees and vegetation from light pollution which is now being recognised as a threat to nocturnal predators and their prey, and collectively can form an important, if fragmented, part of urban and rural landscapes.

In addition to functioning as important refuge for wildlife in intensively farmed or urban areas, graveyards and cemeteries are often places of peace and contemplation, and unmaintained areas are places of wildness and spirituality that are a vital to the heart of graveyards – although many people are unfortunately unable to recognise this.

We should protect and enhance our graveyards and cemeteries for our wildlife, not just because they are special places but they can potentially be linked together with other public areas such as parks to form connected areas of habitat that would allow our wildlife (and the benefits they bring us) room to live and move safely between areas.

The project

The study assessed six graveyards across Tayside and four dusk surveys and one dawn survey were carried out on each site using two bat detectors - one passive detector that was placed in one spot and recorded all passing bats, and the other a handheld recorder that enabled Jean to walk around the graveyard and observe bat foraging and roosting behaviour, occasionally helped by some of the TBG members.

A dawn survey was carried out in early August on each of the sites to pinpoint the locations of any bats roosting in the buildings on site (this was external only as none of the buildings were entered).

The Results

Overall, there was more general bat activity in the graveyards and cemeteries than expected, with all graveyards showing some level of bat activity.

Five of the six graveyards contained bats roosting on site, or close by, and several important roosts were found during the surveys, including a large brown long eared bat maternity roost in Clunie Church and rare Natterer’s bats in Blairgowrie. One graveyard, the Hill Kirk which is situated next to established quality habitat, was found to contain all five species of bats found in Tayside.

However, it was found the graveyards in poor quality habitats had disproportionate importance to the bats present than graveyards in better quality habitat. The Dundee Howff cemetery is situated in the city centre and has no connectivity to any kind of habitat whatsoever but was found to contain a solitary male pipistrelle who foraged solely inside the cemetery. A similar situation was found in Carmyllie graveyard that has no nearby habitats or connectivity in the surrounding intensive arable farmland, so the bat populations foraged throughout the night in the graveyard and manse garden next door.

These isolated graveyards therefore have a disproportionate importance to the bat populations present because they rely solely on this habitat to survive.

Only the two species of pipistrelle were measured against the vegetation features (because there was not enough data from the other species of bat) and the results showed they preferred graveyards with mature trees and large vegetation, with the soprano pipistrelle strongly associated with sites near to water.

Observations during the survey supported this, with both species of pipistrelles appearing to forage solely around the trees and large vegetation, and it is clear that the mature trees present in the graveyards are vitally important for both species of pipistrelle.

For the other species of bats, such as the brown long eared bats and Natterer’s bats (present but not measured in this study), previous research has shown that tree cover, understorey vegetation and natural meadow are all important habitats for the insects they forage upon to the extent that in areas where their habitat has been destroyed, those species of bat are no longer present.

Common pipistrelles are known to be generalists that will forage over different habitats and as such appear to be the most tolerant of artificial light, which had no effect on their activity in this study, however soprano pipistrelles were associated with lower light polluted graveyards. Both brown long eared bats and Natterer’s bats are known to be light intolerant bats and will avoid lit areas, even at the expense of their survival.

The light pollution was expected to be severe in Blairgowrie Cemetery but was actually much lower than expected due to the mature deciduous trees lining the outside of the cemetery blocking the light with their leaves, and the fact that the expected spotlights from the primary school next door were not switched on during the summer survey season due to the late sunset times. The light pollution from the buildings in Meadowside Road beside the Dundee Howff cemetery were severe and the one pipistrelle present in the cemetery foraged away from this area.

The maintenance of the graveyards was considered, based on the grass cutting regime, but the pipistrelles appeared relatively unaffected by the maintenance of the graveyards because of their clear preference for mature trees and vegetation. However, maintenance regimes will have a definite impact on brown long eared bats and Natterer’s bats in places where they are present.

This project shows that that even the most unlikely graveyards have potential to support bat populations and simple measures can be taken by graveyard managers to protect their bat populations.

In areas of poor habitat such as unconnected urban areas and intensive arable farmland, graveyards and cemeteries have a greater proportional importance to their bat populations because they provide the only foraging area for the bats and the loss of this habitat is likely to be mean the loss of local bat population.

In this study, Carmyllie and Dundee Howff provide examples of these type of graveyards, and because such marginal habitat are normally only suitable for colonisation by pipistrelles who mainly forage around trees and large bushes, the mature trees in these sites should be protected as much as possible.

In addition, small graveyards and cemeteries have value in the wider landscape as part of a connected framework of green areas that can reach across a wide area of urban or arable land to connect areas of quality habitat.

General recommendations

Firstly, it is important to preserve the features already present and used by the bat species found in the graveyard: for all species of bats this is the mature trees and bushes, and in addition for the brown long eared bats and Natterer’s bats this is also the long grass and lower vegetation.

The bat roosts in buildings are protected by law and simply require to be left alone, and because bats do not chew or make nests they normally do not cause any problems. Bat boxes could also be installed to provide extra roosts.

In addition to their importance as a foraging area, the mature tree canopy and vegetation also prevents light pollution from entering the graveyards. If it is necessary to install lighting, use directional downwards lighting only on the areas needed to avoid unnecessary light pollution and be careful not to install lighting that shines on roofs or any other potential bat roost. Bushes can be also planted to shield areas from light pollution.

Secondly, in areas where brown long eared and Natterer’s bats are likely to be present, “wild” areas could be left in the graveyard with the grass uncut and night scented flowers planted to encourage moths and other insects. Hedges provide shelter and a safe commuting route for bats, are valuable to many other animals and birds and could be considered, particularly if they connect areas of habitat. Dry stone walls are also valuable and could be installed if ongoing hedge trimming is an issue.

Lastly, because people generally do not recognise the value of wild areas, it is recommended information boards are used to inform the public on the purpose of such areas.

Click here for the Hill Kirk project