PRESERVING THE MULRANNY FERAL GOAT: SO-CIAL ORGANIZATION IN RELATION TO OVERALL

NUMBERS AND GENETIC INTEGRITY

RAYMOND WERNER, NOVEMBER, 2010

BACKGROUND

Limited knowledge to date would suggest that the Mulranny feral goat population comprises at least two nanny groups, one of which has largely retained its ge-netic integrity as being of Old Irish type, whilst the other may have more recent Modern type input from domestic escapees or releases. As a first step to pre-serving these goats as an Old Irish breed resource (a rare breed, in fact), we need to know more about the Mulranny goat’s social structure and organization, its daily, seasonal and annual cycles of behaviour, and whether or not it is func-tioning as a closed system. We cannot answer these questions without data from focussed casual observations, monitoring and field studies, although some back-ground information on feral goats in general, and how this relates to the limited information on the Mulranny goats that is available, is here presented.

TERMINOLOGY USED

When feral goats were first written about, it was assumed that their population dynamics and behaviour were similar to that of the Red Deer. Thus it was that any group of feral goats seen together was thought of as a ‘herd’, and assumed to be the sum total of goats frequenting and moving around in that particular locality. One aspect of this was that ‘herds’ were not uncommonly encountered during the rut- meaning when the males and females had come together in a loose association- leading on to the assumption that the nannies and billies re-mained together throughout the year. Later, it was thought that some herds might be but part of a bigger herd that wasn’t always together. Also, because of the analogy with Red Deer behaviour, male feral goats were assumed to be ‘herd leaders’, along with the popular idea of a ‘king billy’ who reigned supreme until replaced by one of his more vigorous sons.

What we now know is that the social organization and behaviour of feral goats is quite complex, is not analogous with that of deer, and thus loose terms like ‘herd’, ‘group’, ‘parcel’ and ‘party’, as applied to any group of goats seen to-gether, simply will not do.

What is needed is a system of terminology, along with consistent definitions, that reflects accurately the range and complexity of feral goat associations. Those

here presented are therefore the present writer’s attempt to both define and name usefully the range of feral goat ‘groups’ that may be encountered.

GROUP STRUCTURE, POPULATION, AND OPEN OR CLOSED SYSTEMS

The Basic feral goat unit is the nanny-kid group. Nanny-kid groups are heavily hefted onto a home range. This consists of a familiar terrain that provides var-ied food resources, familiar trails (predator proof escape routes) dry beds, gen-eral shelter and kidding ranges. Additionally, high dry ground that offers vantage and sunning areas is of high value.

Family groups are matrilineal female groups based upon mother-daughter as-sociations and their current kids. They may be extended to include grand-dams, dams, yearlings and kids in a direct family line. Also hefted and strongly bonded. When moving, each goat follows its immediate parent, so that the oldest female is the natural herd ‘leader’. Close genetic relationships may lead to stereotypical colours or colour patterns.

Nanny groups are an association of two or more family groups, and is what is generally thought of as being ‘a herd of goats’. Behaviour interpreted as being a ‘herd instinct’ is in fact the coordinated movement of individual goats following their parent. Again a matrilineal society, in which the oldest female with the most descendants is the matriarch (‘leader’). May be very cohesive or fragment into its individual components of family groups, coming together again at intervals. Known also as a family party or a parcel of goats.

Billy groups are known also as puc groups or bachelor groups. Males may bond and remain together over extended periods of time. Usually formed of males that have known each other as kids, and at which time their mock fighting has estab-lished the adult hierarchy. Wide age range, including yearlings.

Mixed groups or a mixed association comprises both adult males and females. By definition is a billy group or individual males joining a family group or nanny group. Is typical of the rut, but males may come and go ad hoc during other times of the year.

Population is the sum total of nanny groups with attendant males in a well-defined area, that may be considered to be discrete unit distinct from other pop-ulations.

Open system. A population that may be visited or permanently joined by males from outside the area, thus leading to a wider genetic variability.

Closed system. When there is no goat movement from outside and into the home range of a population. The basic units described above are highly stable, although nanny groups may split, with a family group moving onto a new home range. Over time, the links between the two groups may weaken and be lost. Nanny group numbers are variable, although historically between twenty and thirty have been oft time quoted. In Ireland, and particularly on the Burren, what

appears to be highly stable nanny groups in excess of a hundred have been monitored.

HOME RANGE

The home range isn’t a territory, but a well-defined area within which groups move, and outside of which they will not generally venture. All a feral goat’s needs are met within their home range, and its size may vary. About one goat per acre may be considered standard, although there is a wide variability based upon the terrain, natural boundaries and available resources. Female home ranges may vary in size and topography from male home ranges, although they will overlap as well as have unique features. Within a home range there will be daily cycles of movement based upon specific activities, as well as seasonal movement patterns.

DAILY, SEASONAL AND YEARLY MOVEMENT AND BEHAVIOUR IN RELA-TION TO GROUP STRUCTURE

The daily cycle of behaviour may be divided into periods of feeding-idling-ru-minating whilst lying-up-feeding again, in a predictable and well-defined series of activities. Groups typically feed in the early to mid- morning, lie up to ruminate from the late morning, then have a second period of feeding from the mid- to late-afternoon and into the evening. Feeding periods gather momentum with an optimal period of intensity, then wind down into a period of idling just prior to ly-ing-up. It is characterized by grooming (self and mutual), mock or play fighting, hierarchical activities, investigation and watchfulness. These behaviours imply a high level of social bonding and reaffirmation. The pattern and duration of activ-ity cycles may be influenced by seasonal variations in weather patterns and food availability. For example, lying-up periods may be extended on hot and sunny days, and the goats may be skittish and restless on stormy/windy days.

Movement is dictated by feeding patterns, groups feeding in well-defined cir-cuits that may be adhered to over several days then switched to another. It is therefore possible to familiarize oneself with both the feeding circuits and pat-terns of behaviour of a group, and thus predict where they may be at any one time. Individual family groups may become detached from each other during feeding periods, but come back together again as a nanny group when lying-up. Heavy storms may fragment a nanny group, also something as basic as a family group, even individuals, lingering longer ar a feeding station (i.e. a furze clump).

Variations in seasonal patterns of movement are dictated by climate and available food resources, examples being flowering furze in the spring (sought out particularly by pregnant or early post-parturition females); the optimal nutri-tional value of grasses and ling; budding leaves in early spring, the need for shel-ter and so on. Groups may come together and co-join on rutting grounds, and in-dividual females may move onto well-defined kidding ranges.

Annual cycles of behaviour. Male and female groups tend to come together in loose pre-rutting associations towards the end of the summer. The rut proper,

which begins in the autumn, is the time of optimum mixed group size, and may serve as an indicator of the total numbers of any given population. Billies may linger in these mixed assemblies as the winter sets in, and until such time as the nanny groups fragment for parturition. In some cases nannies may kid alone, and remain solitary into the spring (six weeks or more). As the stability of the nanny groups break down, the males drift away to form bachelor groups. They may, however, visit the reforming nanny groups at any time during the summer months, or temporarily associate with them when male and female groups col-lide on mutual parts of their home ranges. Feral goat movement during the winter months is balanced between the need for shelter (including dry beds), the availability of food resources and kidding areas.

Overall variation in social organization. Some nanny groups appear to be very cohesive and predictable with regard to numbers and movement. In others, the basic unit remains the mother-kid group from kidding until the pre-rut as-sembly. In others still, mother-kid or family units may remain discrete and oc-cupy overlapping individual home ranges, larger assemblies simply being an oc-casion when two or more family units or family groups are feeding in a mutually inclusive part of their overlapping ranges.

Male behaviour. Males are generally more vulnerable than females, more con-sistently seek out shelter, and often feeding on more woody material. They are also significantly more likely to succumb during particularly harsh or wet winters. Thus, their home range needs may be different to those of females, more con-sciously seeking out higher or wooded terrain. There will also be considerable overlap between male and female ranges. Males will leave the family group as yearlings, although they are not fully mature until three or four. Males in the younger age classes will peregrinate on a circuit that will bring them into contact with two or more family groups. Older to old males may ‘wander’, moving consid-erable distances in a vaguely straight line. In respect of this, fifty miles or more has been recorded.

IMPLICATIONS FOR NUMBERS AND GENETIC INTEGRITY REGARDING THE MULRANNY FERAL GOAT

The limited data available to date would suggest that the Mulranny feral goat population is based upon nanny groups, two having been identified thus far. The first- the ‘Bezoar nanny group’, so named after an elderly female of that colour pattern- may consist of around twenty-three animals, including immature males. This group has retained the key characteristics of the Old Irish goat, although it is possible that some Modern goat breeding has been absorbed. The second group- named after a white, tasselled female, and called the ‘White nanny group’- would appear to bring the numbers up to forty-seven or so. This second group has some more overt characteristics of introgression, including the white tasselled female herself and a young Swiss patterned animal.

Focussing on nanny groups as the possible stable association, we need to ex-plore (i) whether two nanny groups comprise the Mulranny feral goat population,

and (ii) whether these two (or more?) nanny groups associate not at all, regu-larly, or at certain times of the year only.

We also, need to know about male numbers and behaviour in relation to nanny groups. In respect of this, it would be useful to know:

• The total number of goats in the Mulranny area

• Whether individual males or groups of males move regularly from one nanny group to another, giving rise to genetic interchange between fe-male groups

• Whether males regularly or even occasionally leave the area, or other males come into the Mulranny area from contiguous populations, thus creating an open system. If the latter occurs, then the breed character-istics of the other population(s) involved will need to be investigated. If not, then the Mulranny population is a closed system, with no outside genetic input

• Because one nanny group appears from photographic evidence (not foolproof) to be of largely Old Irish type with the possibility of Modern type introgression in the recent past, whilst the second group has the more overt characteristics of recent introgression, we need to know more about any genetic interchange between these two nanny groups and whether males of more obvious Modern phenotype move between them.

• After a field study involving longer term observations, a programme will then need to be formulated to contain and reduce Modern type in-fluence on the population as a whole.

BUILDING UP A PICTURE OF THE MULRANNY FERAL GOAT POPULATION FOCUSSED UPON CASUAL OBSERVATION THAT CAN BE ANALYSED, MON-

ITORING AND FIELD STUDIES

It would be helpful to build up a photographic record of individuals that comprise discrete groups, most easily achieved by photographing each individual from either one side only or from both sides. From this, age classes can be worked out.

By grid pattern observations, the total number of goats in the area can be ar-rived at.

By combining the foregoing, population size, age and sex ratios, and the total range of the goats can be worked out.

Casual observations and monitoring can build up a picture of group movements, defining individual home ranges.

Seasonal movements can be monitored for both males and females.

Lastly, information can be gathered on other feral goat populations residing nearby in goat movement terms, meaning near enough to potentially have an in-fluence on the characteristics of the Mulranny goats.

First steps information gathering on the two individual nanny groups could in-clude:

· The location of both. Do they operate as discrete units only, or come to-gether? If the latter, is it regularly, occasionally or seasonally?

· Do individually identified males frequent both groups?

· How wide ranging are these two groups?

· They may have separate home ranges with a shared overlap that brings them together. They may associate only during the autumn rut and early winter, but remain separate during the spring and summer. They may never associate, but be linked by billy movement.

A part of the Bezoar nanny group. The female after whom this group is named is the tan coloured female at the front