Hill country grazing

Over the last 10-15 years there has been a marked trend towards deer farming on lower productivity, non-arable land - our hill and high-country. This type of land has traditionally been the preserve of sheep and beef cattle dry-stock farming, but more recently deer have also been very successfully integrated into these systems. Deer are farmed there ‘extensively’ in that compared with ‘intensive’ systems on better quality, lowland pastures, they use lower stocking rates and larger paddock and herd sizes.

Deer farmers have recognised that deer biology favours the hill and high-country environments. For example, the complex environments that characterise hill and high-country offer more scope to farmers to provide breeding hinds with more suitable habitats to give birth and successfully rear their calves.

The most commonly used NZ land classification system is the ‘Land Use Capability Class’ or LUC Class. It is an assessment of the land’s capability for use, taking into account both its physical limitations and its versatility for sustained production.

There are eight LUC classes, with versatility of use decreasing, from Class 1 to 8. As a general rule, as the LUC Class increases, topographical variation increases, annual dry matter production decreases, potential deer stocking rate decreases and paddock size increases to accommodate optimum herd sizes.  

Classes 5 to 7 are not suitable for arable cropping but are suitable for pastoral grazing, tree crop or production forestry use (Fig 1). Class 8 land is unsuitable for grazing or production forestry, and is best managed for catchment protection and/or biodiversity conservation. Our extensive deer farming systems are generally in the lowland hill country of the North and South Islands (LUC Class 5-6) and sub-alpine high-country of the South Island (LUC Class 6-7).

Red deer breeding hinds each establish a specific home range, which often overlaps with others, and they also use certain preferred types of vegetation within large hill and high-country calving paddocks.

Figure 2: Haycocks Station GPS tracked hind ranges are identified by different colours. Lighter shaded areas in each home range represent areas more intensively used by each hind. Vegetation types: pasture (light green), scrub (dark green), and tussock (tan).

Each hind occupies a relatively small proportion of the paddock area (<15%) that defines their preferred home range, typically 5-30 ha over the calving period (Fig 2).

Larger, and probably the more dominant, hinds inhabit a very similar home range each year(see Fig 3). The strong hierarchical nature of red deer means that when new breeding hinds are mixed into an existing mob, the entire mob should be given time to establish a new ‘pecking order’ and to enable each hind to find a home range that fits within with this pecking order. Providing this ‘settling in time’ especially before calving will reduce the extent that hinds roam across the paddocks, reducing the extent of inter-hind disturbances, which has been shown to be important for obtaining high calf survival rates.

Figure 3: Home range (outlined as 95% core area) used by GPS tracked Hind 374 at Whiterock Station during calving and lactation in 2008/09 and 2009/10. Several observed behavioural patterns indicated this hind was a larger more dominant hind in the breeding herd. Lighter shaded areas represent more intensively used areas within the hind’s home range.

Hind home ranges span a wide range of paddock elevations, hill slopes, and cover a mixture of pasture, tussock, and scrub vegetation to varying extents (Fig 2) but pasture (the most nutritious and easily digestible herbage) is usually the dominant vegetation type in a hind’s home range (Fig 4).

This is likely to be especially important over late pregnancy and during lactation when high energy and protein feed intake levels are required by the hinds.

Figure 4: Hind core occupancy area (COA) vegetation usage. Haycocks Station and Whiterock Station data combined.

The availability of a variety of habitats is important to a hind when selecting its home range.

Pregnant hinds are more active during the day than at night (Fig 5). Set-stocking within large hill and high-country paddocks provides hinds with an environment - free from human disturbances - in which they feel relatively safe and secure. This could reduce the stress levels of hinds over the calving period, which is important for calf survival.

Figure 5: Hind activity (movement velocity) over the course of a day at Haycocks Station (noon =12). A similar pattern was also found at Whiterock Station.

Scrub usage increases particularly around midday and in the early afternoon (Fig 6).

Hinds use scrub mainly at times of rest/rumination, suggesting that scrub may be used as concealment cover.

Figure 6: Hind scrub vegetation usage over the course of a day at Haycocks Station. A very similar daily pattern was also found for tussock usage at Whiterock Station.

Deer farming could cause unpalatable shrubs, such as matagouri, to spread in scrub and tussock areas. This is caused by low grazing/browsing pressures and high nutrient returns (via deer dung) being applied to these plants in comparison to other vegetation types. If unmanaged this spread could reduce the long term carrying capacity of paddocks. Using greater fencing subdivision to force livestock to evenly graze paddocks and to reduce camping will help control the spread of unpalatable plant species. Using periodic heavy grazing is another option, but care needs to be taken not to damage other more preferentially grazed vegetation such as pastures and tussocks. It is strongly recommended that farmers check with their Regional or District Council if they are wanting to control native scrub plant species, such as matagouri, as many have varying degrees of protection under the Resource Management Act.

Over the summer calving period, hinds do not change their movements (e.g. actively seek shelter) in response to high rainfall episodes or strong winds. However we don’t know whether the same is true over winter when there are likely to be more adverse weather events.

Hinds travel a significant amount 1-2 days before giving birth, move very little for up to a week thereafter, then over several weeks gradually return to normal ranging behaviour (Fig 7). 

Figure 7: Typical hind movement patterns around calving for a hind intensively farmed at AgResearch Invermay. Crimson line – normal activity prior to onset of calving; Red line – marked elevation in movement just prior to calving (on some farms this is seen as fence-line pacing); Green line – birth date; Blue line – post calving period.

In hill and high country environments the increased movement just prior to calving is often far less marked, but instead the hinds show a greater degree of reduced movement for 2-3 weeks after calving compared to more intensively stocked farms.

Hinds look for some form of cover to calve in and subsequently use it for at least for 1-2 weeks after calving.  Larger, most likely more dominant, hinds generally remain on sites dominated by improved pasture, while smaller, more submissive, hinds opt for higher elevation sites dominated more by tussocks.

Table: Hind 24hr post-calving vegetation selection (usage/availability) at Whiterock Station in 2008/09.

Values >1 indicate the hinds were selectively using the vegetation, while values <1 indicate the hinds were avoiding the vegetation. Several observed behavioural patterns indicated Hind 374 was a larger dominant hind in the breeding herd.

Hinds remain within 50-100 metres of the birthing sites for 3-4 days after calving. In the absence of predation, and perhaps reflective of the hinds’ contentment with the birthing environment, hinds prefer to stay with their calves.

Hinds in more intensively stocked paddocks (Fig 8) are more active – and probably more stressed - immediately prior to calving than in the hill/high country. This may reflect increased stress levels in those hinds, which is thought to be a major contributing factor to low calf survival. A high amount of pacing in a small paddock also significantly increases the chances that hinds with newborn calves will be disturbed, interrupting successful calf-dam bonding. 

Figure 8: Percentage (%) of GPS collared hinds showing increased movement 1-2 days prior to calving at the study sites, and an intensively farmed site (AgResearch Invermay) with hinds set-stocked at different densities.

At Whiterock Station, two distinct paddock areas were avoided by breeding hinds over calving and lactation (Fig 9), possibly due to them:

• being very steep (>26o hill slope);
• containing very dense vegetation dominated by tall-tussocks, speargrass, bracken, and large matagouri bushes, acting as a physical barrier to entry;
• lacking palatable plant species; and/or
• being distant from water sources.

The effective grazing area of a paddock, which excludes any large paddock areas likely to be avoided by deer, should be taken into account when selecting deer stocking rates. The use of certain paddock areas can also be encouraged by placing essential resources, such as water troughs, in them.

Figure 9: Areas of the Whiterock Station study paddock not used by breeding hinds over summer and autumn.

Hinds may be forced to use normally avoided areas when resources are scarce. Hinds set-stocked in winter at close to double the stocking-rate used during calving and lactation (summer/autumn) inhabited almost all available habitats, including areas previously avoided (Fig 10).

Figure 10: Areas of the Whiterock Station study paddock not used by breeding hinds in winter before they were given access to a high quality feed source in the form of a kale forage crop.