Trees recognize roe deer by saliva

Smart defence mechanisms against browsing

Date: September 12, 2016

Source: German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig

In spring, the young, delicate shoots in the forest light up, bright and May green. The buds and shoots are the future of the forests as they allow young trees to grow. The problem for the trees is: Roe deer like to eat them, and especially their buds. With a bit of luck, the young, gnawed saplings will only take a few more years to grow than their non-bitten conspecifics. In the worst case, they will become stunted trees, or they will have to give up their fight for survival after a number of years. In this respect, roe deer can cause a great deal of damage and hinder the regeneration of many deciduous tree species.

In order to protect themselves against roe deer browsing, trees purposely put up a fight. By studying young beeches (Fagus sylvatica) and maples (Acer pseudoplatanus), biologists from the Leipzig University and the German Centre for Integrative Biodiversity Research (iDiv) have now found out that trees are able to recognise precisely whether a branch or bud has been purposefully nibbled off by a roe deer -- or just randomly torn off by a storm or other mechanical disturbance. The saliva of the animals gives them the signal. If a deer feeds on a tree and leaves its saliva behind, the tree will increase its production of salicylic acid. This hormone, in turn, signals to the plant to increase the production of specific tannins. It is known for some of these substances that they influence the feeding behaviour of roe deer, with the result that the deer lose their appetite for the shoots and buds. In addition, the saplings increase their concentrations of other plant hormones, growth hormones in particular. These hormones enhance the growth of the remaining buds to compensate for the lost ones.

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Will roe deer persist? Climate change spells disaster for species unable to keep up

Date:

April 1, 2014

Source:

PLOS

Summary:

As the climate continues to change, it's unclear to what extent different species will be able to keep pace with altered temperatures and shifted seasons. Living organisms are the survivors of previous environmental changes and might therefore be expected to adapt, but are there limits?

Continued

Roe Deer More Likely to Be Run Over at Nightfall On a Sunday in April

Apr. 23, 2013 — Traffic accidents involving wildlife are on the rise in Europe. The establishment of a time pattern for the accidents could be useful for increasing safety and preventing human and animal deaths. On the basis of this objective, a team of researchers have established at what time, on what day of the week and in which month accidents involving boar and roe deer are most likely to take place. 

Car accidents involving animals are a serious and growing problem in Europe. They pose a risk for human life and may result in mortal victims, damage to vehicles and the loss of wildlife. 

Specifically, in Galicia the time distribution of the accidents varies according to the month, the day of the week and even the time of day. This is the main conclusion of a study published in the 'European Journal of Wildlife Research' by a team of researchers from the AF4 group from the School of Forest Engineering at the University of Vigo. 

Wild boar are the cause of 63% of traffic accidents involving wild ungulates, and roe deer come second, in 37% of the accidents. The researchers analysed a database of 6,255 accidents of this type. 

"Drivers must understand that many roads pass through the habitats of these species, and that it is necessary to reduce speed, especially in certain seasons or at certain times of the day," as explained by Laura Lagos, main author of the study. "Road traffic managers are also responsible for signposting the sections of the road at greatest risk." 

Two periods can be distinguished in the year with a higher probability of accident, varying according to the species, but not linked to human factors such as the annual volume of traffic. 

Accidents involving roe deer occur more frequently between April and July, particularly in April and May. "This is the season in which the young roe deer born in the previous year are expelled from the group and start to look for a new territory," explains Lagos. However in July, accidents are probably linked to the mating season. 

On the other hand, accidents involving wild boar tend to take place between October and January. "Nights are longer during these months, and therefore the probability is higher as they are nocturnal animals," adds Lagos. In addition, in these months, which coincide with the hunting season, the beaters chase the animals away and they often cross the roads in Galicia." 

The risk is greater on Sundays 

The number of accidents also increases at weekends, especially on Sundays, due to the increase in the volume of night-time traffic. In the hunting season, the accident rate is higher on Sundays. 

The frequency of accidents during the day is linked to the activity of the species. Wild boar are nocturnal and roe deer are more active at dawn and nightfall, which is reflected in the distribution of the accidents. 

As well as making drivers more aware of and signposting the more dangerous sections, Lagos believes that "the creation of GPS- and mobile phone-based systems to warn drivers as they approach risk zones may be a more efficient system in Galicia and in the rest of Europe. We are working on this project together with the GEODEM spin-off." 

http://www.sciencedaily.com/releases/2013/04/130423091033.htm

Do we need to cull 50% of UK's deer?

Deer do need controlling? 50% seems a very high estimate. 

Scientist claims there are more deer in the UK than at any time since the Ice Age
March 2013. Current approaches to deer management are failing to control a serious and growing problem, according to new research by the University of East Anglia.

Roe & Muntjac
Researchers drove more than 1140 miles at night and used thermal imaging and night vision equipment to quantify the population of roe and muntjac deer in a unique study spanning the border of Norfolk and Suffolk. The results show for the first time that present management efforts are not enough to stop populations spreading out of control.

There are more deer in the UK than at any time since the ice age. In the absence of natural predators, populations are continuing to expand - causing a serious threat to biodiversity, as well as road traffic accidents and crop damage.

Breckland
The research team investigated the numbers, sex ratio and fertility of roe and muntjac deer across 234 km2 of forested land and heathland in Breckland, East Anglia, to measure the effectiveness of deer management. It is the first time that such a landscape-scale study has been carried out in Europe and the first time that control efforts have been compared to known numbers.

Deer ‘pushed out'
They found that while deer management appeared to control numbers at a stable level, this was only because thousands of deer are ‘pushed out' to the surrounding countryside each year, helping drive the further spread of deer.

Wildlife Extra asked UEA about the results of this 'pushing out', and whether other areas would be the same so Breckland would also be importing deer.

Read on:  http://www.wildlifeextra.com/go/news/deer-cull013.html