The Ecology of the Grey Partridge (Perdix perdix)

Partridges, when anyone comes near their nest, cast themselves down before his feet that looks for it, running and flying as if they were lame, by that means drawing him away from their nests and enticing him to follow them; which when they have done, themselves fly away.

Aristotle (384 – 322BC) quoted in John Ray, The Ornithology of Francis Willughby, 1678.

The grey partridge, Perdix, was originally known in Ireland as the ‘pertridge’, ‘partryche’ or ‘pertriche’ when its ‘rusty-gate’ call was heard in the Irish countryside. The species was once very numerous and well known to those living in the countryside across farmlands stretching from Ireland to Mongolia.

Always a popular bird, it was first introduced very successfully to North America so that it now occupies a total area of more than 12 million sq. km worldwide, considerably greater than the area of Europe and one of the largest ranges of terrestrial birds. Classified as a ‘specialist’ farmland bird species, it can be equally at home in mountain and lowland meadows, arable farms (upland or lowland), steppe grassland, raised bogs, peatland perimeters, sand dunes and young plantations. The numbers prior to 1953 were estimated at about 110 million globally (Potts 1986) but they are now very seriously in decline everywhere.

Grey partridge global distribution in the early 1980’s had a range of 8.5 million sq. km in 47 countries. It was successfully introduced to the US and Canada where it occupies a range of 3.5 million sq. km (Potts 1986). The Perdix partridges originated at least 3 million years ago on the grasslands in the area that has been raised to form the Tibetan plateau. Bellicourt, in Picardie, France has the highest average recorded density of grey partridges in the world (Jacques Hicter).

Adult Characteristics: The Grey Partridge is quite a colourful bird, despite its name, with its light-orange face and intricately patterned brown and grey plumage. The bird has a small, neat head, brown bill, streaky back, a grey-streaked breast and striking chestnut bars on each side of its round plumb body. Approximately 28-32cm in length, the belly in both sexes is white, usually marked with a large chestnut-brown horse-shoe mark. In flight the tail fans open to display a warm orange and the pale wings are slightly curved and fingered. The only major and constant difference between the sexes is the so-called cross of Lorraine on the tertiary coverts of the females – these being marked by two transverse bars, as opposed to one in the males. These are present at around sixteen weeks of age when the birds have moulted into adult plumage. Their bird song is a creaky and rhythmic, a low chirrick or kieerk.

Habitat: The Grey Partridge is generally seen in open grassland, heathland edges and farmland, especially with mature hedgerows. Where the birds exist, families of them collect together in flocks knows as ‘coveys’ which when disturbed, will fly off as one, their arched wings beating rapidly between intermittent glides. Grey partridge will cover 4m in the first second after take-off, leaving predators to rely on surprise (Potts 2012). This quick exit ensures no scent is left for Mr Fox to trace as the partridges find a new safe refuge. The birds feed and roost on the ground, spending the autumn and winter in groups (coveys) of a dozen or more.

Breeding: Pairing takes place in spring and nests are also made on the ground, usually in dead grass and other dead vegetation, keeping them safe until incubation can start. The female chooses her male breeding partner unlike other game bird species. After laying of the second and subsequent eggs, the hen covers them carefully with dead grass and other dead vegetation, keeping them safe until incubation can start. The clutch size of the grey partridge is large, around 15 but rising to 18 in areas where the onset of spring is later and more rapid. Although the hen produces only one brood per year the number of eggs laid is high by comparison.

On average chicks hatch in 25 days, after which they are dependent on insects for the first three weeks of life. Chicks are able to flee ground predators by the tenth day and they can fly properly for short distances at 15 days. After fledging, the family stays together often joined by neighbours without chicks, especially bereaved males, to form the covey. Outside of breeding season, coveys feed at dawn and then especially at dusk, preferably gleaning grain and larger weed seeds from cereal stubbles, spending the rest of the day in cover.

In fine weather, the night is spent in a tight group in open areas preferably 25-80m from the nearest tree; a behaviour known as ‘jugging’. Coveys break up with pair formation when the young males, but not the females, disperse from their birth area. In Ireland this dispersal usually takes place in early February, after which pairs begin to search for nest sites, preferably in tall dead grass tussocks under thorny shrubs or brambles. In the absence of permanent nesting cover they will nest in cereals. This is the time when the risk of predation by raptors is greatest. The entire behaviour of the grey partridge is finely tuned to reducing the risk of predation but it remains the most important source of mortality. The fox being the most important predator of grey partridges followed by the corvid family in particular grey crows and magpies.

Gamekeepers are hugely important in reducing such nest losses. Conservation without including predator control is to defy science as a much as common sense. There is scientific evidence pointing to nest predation being high, not just because of farmland as a habitat but because the top predators are missing from the natural ecosystem. The potential increase in nest predation rates at higher densities of nests appears to be a crucial factor capable of determining the long-term average sustainable survival rate of the grey partridge generally.

Diet: Grey partridges feed on seeds, leaves, caterpillars and insects, picking them up as they move cautiously through meadows and pastures. They will also eat green shoots particularly two favoured green foods of partridge is chickweed and bindweed. Partridges feed on a range of insects: plant bugs, sawfly larva, ants, leaf beetles, weevils, ground beetles, grasshoppers, spiders, flies and caterpillars. All are eaten by adults with the exception of aphids and Lucerne flea that are eaten mainly by chicks in their first week. These insects have become less freely available in recent years due to the use of pesticides and herbicides. This is a critical factor in ensuring the sustainable survival of the adult population in the future.

Captive reared partridge are fed wheat and game grower pellets up to March after which this is changed to breeder pellets. Partridge chick crumb is fed to the newly hatched chicks for approximately five weeks and for the next three are fed a mini pellet. Chick diet can be supplemented with live meal worms in the crumb. At eight weeks old their diet changes to game grower pellets and at twelve weeks old it’s changed to a diet of game grower pellets and wheat in a ratio of 2:1. Captive birds are ready for release to the wild at 16-18 weeks. Parent reared family groups/coveys is the best strategy for restoration projects allowing the establishment of a self-sustainable population without the need for continuing release. The provision of oyster shell or limestone grit helps aids digestion and provides supplementary calcium.

Diseases: Mortality of partridge peak at three life intervals following birth: 8, 24 and 31 days (Alan Pearson MRCVS 2014). The main diseases affecting partridge are: E.coli, coccidiosis and gape worm.

E.coli (Escherichia coli): can be found everywhere if you look for it. A rod shaped bacteria that commonly colonises the bowel of warm blooded animals within 48 hours of birth. The clinical signs can vary from sudden death to an impression that the partridge are not doing well, but generally affected birds appear unthrifty and have ruffled feathers. Usually they are not eating and may have yellow-coloured and wet droppings. E.coli infections can have a number of sources from hatchery to hut conditions. Treatment includes: prescription of antibiotics by your vet but only part of the answer. Secondly, you need to find the stressors – substandard heat, light or cleanliness should all be reviewed. Finally, food and water quality must be optimal. Additional fluids that contain minerals in soluble form may be required to kick start the birds (e.g. Tribisson).

Coccidiosis (Eimeria Coccidia): this parasite has a life cycle of about seven days. The organism lives in moist conditions and can be found around the bases of drinkers or patches of wet ground. Symptoms include partridges being a little dull and ruffled. In more serious cases there may be weight loss, lethargy, dehydration, diarrhoea and death. In partridges the signs can come on as quickly as sudden death. The difference between partridges and other game birds is that the partridge immune systems don’t seem to learn and will go on to suffer quite badly for one or two more cycles. Treatment is straightforward with a coccidiostats placed in food or water. The latter being more palatable. Available from your vet there are two types available: Baycox (Toltrazuril) or Amprolium – as recommended by your vet. Other methods for effective control include: paying attention to the hygiene of the birds drinkers and feeders and the ground under them. Do not re-use old infected pens or equipment and certainly do not overstock pens. Coccidiosis can be among your birds without you ever realising. Clean ground will help reduce initial challenges and keeping your birds as stress-free and healthy as possible will help them through the initial outbreak.

All these points should help to reduce the peak mortality in the first week on the grass.

Gapeworm (Syngamus trachea): can be seen as the partridges throws back its head with mouth wide open in an effort to straighten or stretch its windpipe and can be heard as the bird gasps for breath. The partridge may also noisily and convulsively shake its head or try dislodge the worms from its trachea. The clinical signs are an outstretched neck and open mouth, hard of breathing or gasping for breath – hence the name ‘Gapes’. Signs may just be a mild pneumonia or lack of condition because the worms will suck the blood from the fine blood vessels in the windpipe.

There is three development stages in the gapeworm eggs: the larvae can be hatched and picked up by other birds. They may be picked up unhatched and hatch inside the bird. Others may be picked up by earthworms, slugs, snails or maggots, the larvae of the house fly or the bluebottle, all known to be paratenic hosts. Wild birds particularly the crow family, corvids such as magpies transmit the disease as they visit or overfly game bird pens, though robins and starlings can as well.

It is possible to reduce or eliminate infestation of the gape worm by breaking the cycle using one or more of the following methods:

• Pen rotation – moving the pens to clean ground will have a dramatic effect.
• Reducing stocking densities – less birds, more space and less worm eggs.
• Good hygiene – of pen structure, drinkers and feeders.
• Removal of potential carriers – e.g. crows, starlings and magpies.
• Worming & moving – a proven strategy to ensure transfer of infected birds to a new pen thus reducing the likelihood of further worm infestation on new ground. A licenced wormer from your vet which may be included in the feed: Flubenvet or Solubenol which contains the same active ingredient (flubendazole) is available for poultry species or could be used where in feed medication is not available or practical.

Top five tips for a successful grey partridge re-introduction

1. Ask for advice tailored to your land management and farming practices before making any attempt to re-introduce grey partridges.
2. Do not re-introduce grey partridges if you have over two pairs per 100 hectares on at least 400 hectares. Aim for a recovery project instead.
3. Before starting your re-introduction project make sure you improve the habitat, intensify predator management and provide feeders for supplementary feeding.
4. Where there are none or very few grey partridges still present, fostering young greys to wild-living pairs and parent-reared family groups is the best strategy to start with.
5. Reduce the risk of accidental shooting and disturbance to grey partridge during the breeding season by ensuring adequate nesting cover, foraging cover and winter escape cover. See Department of Agriculture, GLAS environmental scheme for biodiversity action plans to help habitat restoration for this popular gamebird in areas where it previously went extinct.

The decline of the grey partridge has been a barometer for biodiversity over the past forty years. Wildlife can continue to thrive as it did before pesticides were introduced. Conservation techniques such as riparian margins, beetle banks, wild bird seed, cover crops and effective predator control will enable the conservation of the grey partridge for future generations. As landowners and farmers respond to an increasing global population, the pressures on farmland wildlife will further intensify in the coming years. It is important every effort is made by current and future policy makers to ensure the sustained revival of this farmland bird – the grey partridge.

©Mervyn Walsh

Gorteen Wildlife Conservation Trust