Deer management

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Deer management in Ireland is a very important role for the future of our deer species for their health and sustainability and should be implemented in every possible way and should be carried out at every opportunity possible , A sound knowledge of deer behaviour is essential for the efficient management of deer.
This guide describes features of deer behaviour which are more or less common to Irish deer species (see Species guides for behaviour specific to each), but each species is different, deer are very adaptable, and their behaviour can vary widely with habitat, deer density, and human disturbance.

Deer are usually found in or near to forest/woodland/scrub and frequently feed on grass or arable land near to cover. Some species are content to live on open areas of heath or moorland. Deer are very adaptable and may be seen in peri-urban or urban situations or other places where there is cover and a food source, they can have marked preferences for different habitats according to deer species, habitat type, the time of year or weather conditions.

Deer may form herds or act in a more solitary manner according to species, age and sex.
Solitary deer tend to be territorial, especially the males. Herding animals are more inclined to form groups, members of a herd may often be closely related.
Herds or individuals tend to be “hefted” to an area in which they prefer to live, this tendency is strongest in territorial deer and females of the herding species. The herding deer may have “core areas” sometimes several miles apart, using these at various times of year but rarely being seen on the intervening land.
It may sometimes be possible to identify the home range of a herd, group or individual by sightings and the signs that they leave behind (Deer Signs guide).
The relationship of young deer with adults varies with species,
Where different species live in the same area, they generally live separate lives but there may be passive competition for resources and possibly a degree of aggression.

Deer are relatively shy animals which may give the impression that there are fewer around than there actually are. They are alert to danger and will respond quickly, usually by running away and/or seeking cover but sometimes lying up in or running into wide open areas where they can assess threats. Deer can be easy to stress but recover quickly when the threat is removed. One common response to
persistent disturbance is for deer to change their behaviour, e.g. by avoiding busy times/places or becoming nocturnal. This plasticity of behaviour must be taken into account when planning deer management.

Deer have evolved as prey animals and prefer to spend their time in cover or where they feel secure. With a large rumen( see Deer Biology) they can ingest large quantities of bulky plant food then return to safe areas to lie down (couch) and ruminate(chew the cud). For most species this means that when undisturbed they tend to feed and couch on a 2-4 hourly cycle. Often though, the majority of movement will be at dawn and dusk and sometimes at night.
Deer graze and browse, that is, taking ground-level plants, as well as food from higher shrubby plants and trees. Each species has its own preferences which may vary according to habitat, some are especially selective in their feeding habits. Feeding deer can come into conflict with human interests, in some cases damage by deer to sensitive habitats, crops and even gardens can be serious.
In woodlands, deer at the right density can be of benefit but at high density over a long period they can eat all palatable woodland plants within reach and are forced to range further from woodland to feed. This can bring them into conflict with surrounding landowners and may cause an increase in road accidents. The flora and structure of woodlands can be changed markedly by high deer numbers and such changes may be damaging and long term.

With the exception of Muntjac, which breed all year round, most deer have an annual mating period (“rut”) which varies in timing with species. Around the rut males become more aggressive (sometimes also less timid towards people) and tend to move more outside of their normal range making them unpredictable and more vulnerable to traffic accidents. The larger species may have traditional rutting areas which temporarily become very busy until the rut ends.
Females of herding species often leave the herd to have their young, returning only when the young are strong enough to run with the herd.
For the first few days of life young deer are often left hidden in cover for hours, during which time their mother feeds, then returns to suckle them, this can lead to well-intentioned humans picking them up and disturbing a perfectly natural situation. The best advice is to return the young deer as soon as possible to where it was found, usually its mother will reclaim it. Young deer can be vulnerable when hidden in silage and hay meadows which are due to be cut.

Deer of both sexes can be surprisingly aggressive to each other, this aggression is usually linked to status within the herd or local population and/or competition for food, space and breeding status. Aggression usually takes the form of barging, kicking (sometimes boxing while standing on their hind legs), biting and more subtle facial or vocal expressions.
When antlered males clash the initial stages may be ritualised but fights usually result in the clashing of antlers and strenuous head to head shoving match, the winner is usually the strongest, not necessarily the one with the largest antlers.  Species such as red deer maintain a more or less linear hierarchy where each animal knows its place above and below the next. The usual reaction to humans, dogs or predators is to run, if possible to cover, although cornered deer, males in the rut, or females with young can be very aggressive if threatened. Hand reared deer of both sexes can be very dangerous.

Deer are generally quiet but most have specific alarm calls, calls between mother and young and male calls during the rut, some have female calls when seeking a mate or giving birth

Deer tend to use well-trodden paths known as racks to move within cover and to and from feeding places. Using these and other deer signs it is usually possible to build up a picture of how deer use a habitat.

Deer tend to move more and thus be more visible at certain times of the year such as when establishing territories, during the rut, when females are heavily pregnant and when food is scarce. Deer may also be less obvious at times such as when females have newly born young, males post rut or all deer in harsh weather.
The males and females of larger deer ( Red, Fallow, Sika) may spend most of their year in segregated herds, the males moving into female areas only during the rut or sheltering with them in harsh weather.

Deer tend to move more at dawn and dusk but can be active at any time of day or night. Older animals tend to be more cautious and may move later in the evening and retreat to cover earlier in the morning than younger ones

Deer can be sensitive to cold winds and during these conditions may prefer not to come into the open or to feed on the sheltered side of woodlands or hills. In woodland long, straight rides may act as wind tunnels, discouraging feeding deer when it is windy.

Prior to heavy rain or snowfall deer often have a burst of feeding activity. They will seek shelter from heavy rain but will emerge if rain persists for days.
After heavy snow deer may lay up for a day or two, thereafter activity increases and they tend to move up onto moorland/heathland, hilltops, windblown banks and the side of forestry tracks where snow is thinner.
If the sun appears following periods of heavy rain or during a thaw deer tend to move out in the open to avoid dripping trees.

In very hot periods deer may be less active, generally restricting their movements to dawn, dusk and night.
In the early mornings deer may often be found on east facing wood or field margins enjoying the first rays of sunlight.
During periods of hard frosts deer lay up and feed in areas benefiting from the sun’s heat, this frequently results in increased movement during the warmest parts of the day.

Deer tend to move more under bright moonlight than on darker nights , Deer tend to seek cover when disturbed. If continually harassed they may become extremely shy, become nocturnal or leave the area altogether.

Deer are not always easy to see but wherever they go they leave signs of their presence. Careful observation can help to confirm that deer are in the area and how they are affecting their surroundings

If other browsers such as sheep, cattle or horse are not present, one of the best indicators that deer are present in woodlands is the presence of a horizontal “browse line”. This may be particularly obvious on such plants as climbing Ivy or the lower branches of trees or shrubs. The height of the browse line can give some indication as to the deer species present, where more than one species is responsible the browse line height usually reflects the most numerous species or the largest. Deer can stand briefly on their hind legs to feed which can mean browsing is sometimes higher than expected, this is especially true in deer parks. Muntjac can reach high leaves by breaking stems to bring them within reach.

Deer “graze” eating plants at ground level and “browse” at a higher level, eating buds and leaves, especially the tips of leading and side shoots of trees and shrubs. Woody shoots freshly damaged by deer will often show a clean cut on one side (usually the lower) and a ragged tear on the other due to the biting action of the lower incisors against the fleshy pad of the upper jaw (they have no upper incisors). This type of bite is also characteristic of other ruminants e.g. cattle, sheep and goats, but fortunately such animals usually leave other obvious signs of their presence. Rabbits and hares, which have opposing incisors, leave a cleaner, scissor like cut and often part of the stem will be left on the ground.
Brambles are a favourite food and usually show deer browsing clearly.
Provided it is fresh, plant damage by insects, fungi and weather conditions should not easily be confused with deer damage.

Deer hoof marks are characteristically pointed, more so than most domestic livestock. The size and shape varies with species but also with age, so where more than one species is present it might be possible to identify one of the larger species by an adult slot but it might not be so easy to tell the difference between younger animals and adults of a different species.

Deer dung is typically in the form of individual pellets which tend to be cylindrical with one end pointed and the other dimpled. Pellets are usually found in “pellet groups”, small piles or strings, but are sometimes stuck together. Semi-liquid “pats” may be produced by scouring animals or by males in the rut. The size and shape varies with species but also with season and age so where there are more than one species present it might be possible to identify one of the larger species by adult droppings but there could be confusion between younger animals and adults of a smaller species. Rabbit and Hare dung tends to be much more fibrous than deer and more or less spherical.

Deer will “strip” bark from trees and shrubs with their teeth, the tooth marks often being made vertically along the trunk and of a size and height relevant to the species. Damage can extend well up the trunk as strips are pulled from the tree. Usually smooth or soft barked, semi mature trees are chosen and damage can begin suddenly. Bark damage by other animals such as horses, rabbits, squirrels and voles tends to be quite distinctive and with much wider/narrower tooth marks. When they are in hard antler male deer will use their antlers to “fray”, removing the bark of trees or tall plants (such as thistles). Larger species may comprehensively “thrash” trees, breaking side and higher branches. Sika and sometimes red stags will bole score trees with their antler points. The timing and height of antler damage may indicate the species responsible.

Red, Sika and Fallow create wallows in damp/wet areas. Nearby there will often be rubbed and muddy trees. Wallows are often created by males during the rut but all Red deer like to wallow and a herd may have permanent wallowing sites

A deer management plan (DMP) provides a practical and effective framework within which landowners, land managers and deer managers can acknowledge and then attempt to balance the differing uses demanded from an area of land. A central principle of all DMPs is that good deer management should aim to maintain healthy deer populations in balance with their environment.

Plans provide a basis for collecting and analysing necessary information which is then used to formulate management decisions. Planning and good communication between all involved in deer management avoids misunderstandings by ensuring transparency, The process of developing the plan is in itself of value; it will encourage dialogue and highlight the range of expectations. It should therefore enable better collaboration and further understanding of the management challenges.

Contributions are required both from the landowner and all of the individuals who will deliver the actions identified; this should include both professional and recreational deer managers. Account should be taken of the views of those not directly involved with the preparation and delivery of the plans, particularly other land users such as farmers, foresters and gamekeepers, rural surveyors and wardens. Any relevant grant authorities should also be aware of the plan and might contribute to it. In some situations informing the wider community of the plan may identify legitimate constraints but can also provide an opportunity to promote the work of the deer manager.

It is important that management is carried out to meet objectives which should be realistic Within the constraints of resources knowledge and time. There are usually limitations in terms of seasons, manpower, equipment and time. There may also be opportunities for improvements; objectives should be set with these in mind and Set over a realistic time period. It is often difficult to predict how long it will take to reach an objective, for instance reducing populations from very high levels can take a long time and involve a sustained effort to accomplish. In the case of multiple objectives some will be reached before others.

Usually deer populations should not be allowed to reach the absolute carrying capacity, it is not likely to be good for the deer or their habitat. This implies that most deer populations require some management to hold them at least at the SCC ( “sustainable carrying capacity” ). Human interests (e.g. preventing damage to crops or sensitive habitats) may dictate a further reduction to a “managed carrying capacity” (MCC) ,Currently the only practical method of manipulating population numbers is to cull (increase the “outflow”) and in particular to ensure a sufficient cull of female deer, since they are responsible for the majority of the “inflow”. See the Cull Planning guide. If there are multiple objectives in one area then priorities will have to be set and compromises made. If more than one deer species are present management objectives for each species may vary.
Where neighbours have widely different objectives in managing deer, attempts should be made at resolving differences , If the population reaches “A” ,the “absolute carrying capacity” (ACC), there will be lower recruitment, higher mortality and generally poorer body condition. Emigration/range expansion may increase if the surrounding area is not already saturated. There will be significant impact to the habitat and the original carrying capacity may be reduced

When culling wild deer populations it is important to have a clear understanding of objectives. In general these will be to control deer numbers to prevent over population , control deer impacts on human interests, utilise the deer resource

A reduction cull must focus on the females. During this phase there is little point in being too selective about which individuals are culled as long as welfare is assured. Achieving the female cull target should be regarded as a priority. Opportunities should be taken to safely and humanely cull more females than expected unless it would put female numbers below the final planned minimum. The male and female seasons often overlap. While the females are in season the temptation to make up the cull total by shooting males instead of females should be avoided, a single male deer will remain just that throughout his life but a female deer would be responsible for producing (herself, together with her female offspring) many young over her lifetime. Note that if a population is reduced substantially from a previously very high density, there is likely to be an improvement in the condition of the remaining animals. The consequences of this may be that survival rates improve and females may breed at a younger age. In addition, there may be a degree of “in fill” from surrounding areas. Together these are commonly referred to as population “bounce back”. This must be taken into account in planning subsequent culls and the number of deer culled as a proportion of the population may need to remain high to maintain the reduction in numbers. Reducing numbers from very high levels may take many years to achieve. One off, heavy culls, followed by little or no culling, never achieve a sustained drop in numbers. Reduction culls need to be substantial and usually need to run over a number of years to be effective. They must then be consolidated by following with a realistic maintenance cull.

For a population being maintained at a particular level, the cull for each age/sex class will be similar from year to year. Again, achieving the female cull is a priority but during this phase it is possible to be more selective about which individual animals are culled, according to objectives. Calculating the average number of deer required to be culled each day to meet the cull target by the end of the season provides a good incentive to keep up the culling effort. e.g. a remaining cull target of 56 with 30 days of the season remaining = approx. 2 deer to be culled each day to achieve the target. Census, cull and impact data should be monitored to be sure that an adjustment of culling level is not required. As a very approximate guide, and given that sex ratios are approximately equal, maintaining a static population will require a cull of at least 20% of the population for the larger species (red, fallow, sika), and a cull of around 30% of the population for muntjac. At least half of the total cull should be females. If there are a preponderance of females in the population, the total cull rates, and the proportion of females in the cull, will have to be significantly higher. If population numbers cannot be estimated then other measures such as habitat impact levels may determine cull levels .

Deer Management in Ireland A Framework for Action

please follow the following link to view the pdf file containing the joint published document from the department of agriculture , national parks and wildlife service , the inter-Agency Deer Policy Group, with stakeholder consultation.

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