Perdix Perdix Research Articles

Effects of Hand-Rearing and Radiotransmitters on Flight of Gray Partridge

Takeoff ability has an important role in escape from a predator in the gray partridge (Perdix perdix). Rearing in captivity and radiotagging may impair the takeoff ability of birds. To test this, the takeoff angle, flight speed, and climbing rate of wild and hand-reared gray partridges were measured indoors with an optoelectronic motion analysis system. In addition, we tested the effect of an attached radiotransmitter on the takeoff ability of wild partridges. Wild birds had a steeper takeoff angle (P = 0.001) and greater climbing rate (P < 0.001) than hand-reared birds. The transmitter decreased takeoff angle (P = 0.006) and climbing rate (P = 0.002) of wild partridges. The negative effect of hand-rearing and radiotagging on takeoff ability may increase gray partridges' vulnerability to predation.

Sexually selected vigilance behaviour of the grey partridge is affected by plasma androgen levels

In the grey partridge,Perdix perdixvigilance and calling activity are two sex-dimorphic behaviours that are critical for mate choice. To ascertain whether circulating levels of testosterone directly affect vigilance (i.e. the occurrence of upright alert posture), we compared vigilance scores of testosterone-implanted versus control males both during the normal activity of the flock and after the passage of a raptor silhouette; in the latter case, the calling activity was also recorded. Hormone-treated males were more vigilant than controls in both experimental situations. Vigilance was correlated with calling rate. Testosterone seems to act as a link, relating conspicuous behaviours involved in sexual selection to male quality and physical condition, because of the costs of having high levels of both signalling and androgens.

Density-dependent brood production in the Grey Partridge Perdix perdix in relation to habitat quality

Brood production rate of Grey Partridges Perdix perdix was studied in three areas in Poland in the years 1986–90, by comparing the number of pairs and the number of family coveys after the breeding period. In the study areas, linear permanent nesting cover was mapped and measured. In these areas the brood production rate declined with increasing spring pair density. A positive effect of the occurrence of nesting cover on brood production rate was found. An increase in the population density mostly occurred through occupying parts of the study area avoided earlier, thus presumably less suitable for Partridges. Pairs occupying these less suitable areas, characterized by less abundant nesting cover, had a lower brood production rate, whereas in the preferred areas this rate did not decline with increasing mean population density.

The Effect of Agricultural Landscape Structure on Food Resources and Survival of Grey Partridge Perdix Perdix Chicks in Poland

1. The relationships between the agricultural landscape structure, as a function of arable field size and the occurrence of permanent cover, and the abundance of insect food and partridge chick survival were studied in two areas of Poland. One area had small and large fields (Czempin) and the other had only small fields (Kutno). Brood size was used as an index of chick survival and the number of plant bugs (Heteroptera) as an index of chick food resources. 2. The number of plant bugs in cereals increased with permanent cover in Czempin, but no relationship was found in Kutno where there was more permanent cover and smaller field sizes. 3. The average number of plant bugs was higher in small arable fields than in large fields. However, the number of insects near permanent cover in small and large arable fields did not differ. 4. The mean brood size of partridges in small arable fields increased with permanent cover in Czempin, but not in Kutno. No differences were found in mean brood size between small and large arable fields. 5. Simplifying the agricultural landscape structure could be an important feature of agricultural intensification that results in lower partridge chick survival.

Introductions of Sharp-Tailed Grouse into Maine

Introductions of sharp-tailed grouse (Tympanuchus phasianellus) into Maine were approved by the Maine Department of Inland Fisheries and Game in 1954. Habitat inventories in 1955 suggested >1800 km2 were available for sharptails in Washington County. Seventy sharp-tailed grouse from North Dakota and Ne? braska were hard released near feeders in Washington County from 1957 to 1961. In the mid-1950's there was an interest in finding a game bird suitable for open land habitats in Maine. Prior to the 20th century, the heath hen {Tympanuchus cupido cupido) may have been present in southern Maine and introductions of greater prairie-chickens (T. c. pinnatus) had failed (Applegate 1993). Introductions of ring-necked pheasant {Phasianus colchicus) and gray partridge (Perdix perdix) had not been successful, probably because of lack of suitable habitat and adverse climate (Dorr 1952). Because most open land habitats in Maine in the 1950's were either dairy farms, open peat bog, or commercial blueberry {Vaccinium spp.) barrens, the Maine Department of Inland Fisheries and Game decided to investigate introductions of sharp-tailed grouse {Tympanuchus phasianellus, Fig.l). A brief survey was conducted by Dr. G. A. Figure 1. Male sharp-tailed grouse dancing on lek. Photo by Randy D. Rogers * Wildlife Division, Maine Department of Inland Fisheries and Wildlife, 650 State Street, Bangor, ME 04401-5654. Present address: Research and Survey Section, Kansas Department of Wildlife and Parks, PO Box 1525, Emporia, KS 66801-1525. This content downloaded from 157.55.39.136 on Tue, 05 Jul 2016 05:15:56 UTC All use subject to http://about.jstor.org/terms 106 Northeastern Naturalist Vol. 4, No. 2 Ammann of the Michigan Department of Conservation (now Michigan Department of Natural Resources) in 1954. Ammann (unpub. Rep., Maine Dep. Inland Fisheries and Game) suggested that the focus on sharptail introductions should be in the blueberry barrens, particularly those in Washington County in eastern Maine. Based on Ammann's report, the Maine Department of Inland Fisheries and Game, now Maine Department of Inland Fisheries and Wildlife (MDIFW), pursued intro? ductions of sharp-tailed grouse. Introductions of sharp-tailed grouse into Maine were not reported in the professional literature. Many of the original documents relating to this work have been or are in danger of being lost. This paper was prepared to document the historic introduction of sharp-tailed grouse into Maine and identify probable causes of failure as suggested by Toepferetal. (1990).

Connections of the dorsomedial part of the nucleus intercollicularis in a male non-songbird, the Grey partridge: a tract-tracing study

Vocal control systems have been poorly investigated in non-songbirds. In this study we describe descending neural pathways to the dorsomedial portion of the nucleus intercollicularis (ICo) in a galliform (male Grey partridges) by means of the DiI in vitro tracing technique. The simple and sex-dimorphic vocalizations of partridges, which have a critical role in sexual selection, favour this species as a model system for the study of vocal control mechanisms. Our data demonstrate that the ICo, an important site mediating the activation of vocal behavior in all birds, receives afferents from several important higher centers: the nucleus pretectalis, the tuberoinfundibular hypothalamic region, the dorsal thalamus, the preoptic region and the paleostriatal region. Efferent connections of the ICo were directed mainly to the hypothalamic area. This complex neural pathway is consistent with a major role of ICo in male courtship and vocal performance control.

Long-Term Population Analysis of Gray Partridge in Eastern Washington

Recent studies reported that gray partridge (Perdix perdix) populations have declined throughout Europe and Asia. Gray partridge on the Palouse Prairie of Washington also have been reported to be in decline. Therefore, we analyzed densities of gray partridge on the Palouse Prairie of Washington to determine long-term population trends (1940-92). We also tested for density dependence in recruitment and fall-and-winter mortality rates and attempted to relate annual variation in recruitment and mortality to weather and habitat variables. Spring and/or fall estimates of density were available for 33 of 53 years and varied from 1.3 to 23.2 birds/km 2 in the spring and from 0.1 to 28.6 birds/km 2 in the fall. The population's return point from 1940 to 1954 was 3.45 birds/km 2 versus 6.72 birds/km 2 from 1982 to 1992, indicating that density was higher in the more recent period. Surprisingly, this result contrasts with a series of reports that indicated that the population was in serious decline. We detected density-dependent effects on recruitment rate, fall-and-winter mortality rate, and annual change in population size. Density dependence had the strongest effects on recruitment rate. Recruitment rate averaged 1.55 (SE = 0.27) but ranged widely (0.38-3.38). Fall-and-winter mortality averaged 0.29 (SE = 0.06). We were not able to explain variation in population-growth rate or fall-and-winter mortality rate using habitat and/or weather variables (P > 0.11). Under current habitat conditions, density typically will be 6.7 birds/km 2 in the spring and 10.4 birds/km 2 in the fall and can be expected to vary markedly independent of density. By combining available datasets, we developed a lengthy time series adequate for investigating long-term population dynamics. Such an approach may be possible and informative for other populations.

The Effect of an Experimental Reduction in Predation Pressure on the Breeding Success and Population Density of Grey Partridges Perdix perdix

1. A 6-year experiment is described which was designed to test whether or not predation control, as practised by traditional and currently legal methods, increases (i) the breeding success and autumn numbers of partridges, and (ii) the subsequent breeding density. 2. In the experiment, predation control effort was highly seasonal and designed to reduce partridge breeding season losses by killing resident predators of selected species. 3. The predation control significantly reduced the abundance of foxes, carrion crows and magpies during the critical partridge nesting period. 4. After the nesting period, predators re-established themselves each year, during late summer and early autumn. 5. The predation control significantly increased the proportion of partridges that bred successfully and the average size of their broods, thus substantially improving the production of young. Excluding effects of site and year predation control increased August numbers by 75%. Incorporating the effects on breeding stocks in subsequent years this led to an overall 3.5-fold difference between autumn populations with and without predation control. 6. Predation control significantly increased partridge breeding stocks the following year. Breeding stocks in years following predation control were 36% larger than stocks in years that did not follow predation control-excluding the effects of year and site. After 3 years this had produced a 2.6-fold difference in breeding density between the sites with and without predation control. 7. These results suggest that predators play a key role in limiting production and subsequent breeding density of partridges.

Testosterone-induced changes of call structure, midbrain and syrinx anatomy in partridges

Testosterone (T) treated Grey partridges ( Perdix perdix) of both sexes uttered significantly longer and lower-pitched calls than controls; both these acoustic features play a critical role in mate choice. A morphometrical analysis of the midbrain nucleus intercollicularis showed a cell size increase in T-treated birds regardless of their sex. Histological study of the syrinx did not reveal any sexually dimorphic structure in experimental and control birds; the major T-induced change was a thickening of the external membranes, reported to be the main sound source in Galliforms. In conclusion, T appears able to modify not only some acoustic parameters, but also certain anatomical structures at the peripheral and central levels of the vocal system in a nonoscine species.

The effect of group size on metabolism in huddling grey partridge ( Perdix perdix)

The oxygen consumption of grey partridges ( Perdix perdix) in groups of one to nine individuals was studied at −30°C. The resting metabolic rate (RMR) of huddling partridges was 6–24% lower than the resting metabolic rate of a single bird, with larger groups having a proportionately lower RMR. This energy saving during winter night may allow partridges to lengthen their roosting time and shorten the time spent foraging, thus affording greater protection against cold and predators.

The ecology of the red fox Vulpesvulpes in relation to small game in rural southern England

Diet, population density, dispersion, and productivity of red foxes were investigated in an 11 km2 area of mixed agriculture representative of much of lowland rural Britain, where medium‐sized animals (adult weight 0.3–3.5 kg) were abundant. Four small game species within this size range ‐ brown hare Lepus europaeus, pheasant Phasianus colchicus, grey partridge Perdix perdix, and redleg partridge Alectoris rufa ‐ were also censussed twice a year throughout the study. Fox diet was determined by analysis of faecal material, with diet of cubs at breeding dens analysed separately. Two‐thirds of fox diet consisted of vertebrate prey in the range 0.3–3.0 kg. Prey types of overwhelming importance for foxes in other environments ‐ such as small rodents, fruit and invertebrates ‐ each contributed 10% or less to fox diet. Fox territory size was determined by radio‐tracking eight adult foxes during a three‐year period in spring, summer and autumn. Details of family group size, number of litters per group, and litter size were determined through field observation. Adjacent fox territories (mean size 2.7 km2) formed a contiguous mosaic with individual foxes spending less than 10% of their active time on ground shared with neighbouring groups. Typically each territorial group held an adult pair and had one litter of four cubs. Half of these groups had an additional, non‐breeding vixen. Most known fox deaths were the result of deliberate control by man. Control on a central 4.75 km2 farm reduced adult fox density and eliminated cub production there, and for the whole 11 km2 study site deliberate control was almost sufficient in itself to negate annual numerical increase in fox numbers. The food requirements of foxes living at this density was estimated, and from this the biomass of lagomorphs and gamebirds consumed. Even assuming early dispersal of juvenile foxes, the biomass of these species consumed annually was substantial relative to that available at the onset of breeding. It is suggested that hare and rabbit populations were able to survive this heavy depredation because they have a long breeding season and foxes exploited annual production of young prior to maturity; by contrast, the pheasant population was supported artificially by release of hand‐reared birds.

Effects of hand‐rearing on physiology and anatomy in the grey partridge

Artificial rearing may result in changes in the physiology and anatomy of gallinaceous birds. This may partially explain the poor survival of released birds. To study the effects of hand‐rearing on grey partridges Perdix perdix, we measured the anatomical and physiological characteristics of 14 wild and 15 hand‐reared partridges. Captive partridges were heavier, had relatively larger breast muscles but relatively lighter hearts and livers than wild birds. Wild birds had longer small intestines, longer caeca and relatively heavier gizzards than hand‐reared birds. They also had higher glycogen content and cytochrome‐c oxidase activity in the pectoral muscles, indicating their better flying endurance compared to hand‐reared birds. The results suggest that captivity results in altered anatomical and physiological characteristics, and hand‐reared partridges may therefore be poorly predisposed for an abrupt release into the wild.

Development of temperature regulation in the grey partridge Perdix perdix

The development of temperature regulation in grey partridge Perdix perdix, Galliformes chicks at the age of 0–40 days was studied using three different approaches: 1) heat production was measured by indirect calorimetry of chicks subjected to various ambient temperatures; 2) the ability to resist cooling was studied by subjecting chicks to an ambient temperature of 0°C with either dry or wetted plumage; 3) behavioural responses were studied in a thermal gradient using a video camera and an image processing system. The development of homeothermy was not linear. Absolute metabolic rates increased with age at all temperatures, while the maximal mass‐specific heat production (W×kg ‐0.75) doubled between days 1‐2 and day 5, but remained unchanged after that. Assuming that the allometric exponent accounts for mass‐induced changes in the metabolic rate, this suggests that the increase in maximal heat production before the age of five days can be attributed to both maturation and growth, while the increase after five days can be explained by growth only. At the age of 1–2 days, the chicks' capacity to increase heat production in cold was negligible. In five and 10‐11‐day‐old chicks the capacity was markedly higher, but the maximal heat production occurred already at 25°C. A quantum leap occurred between 10–11 and 15–16 days, when the point of maximal heat production shifted from 25°C to 5°C, which indicates a significant improvement of insulation. Wetted chicks cooled faster than dry chicks until 21 days of age. The relative effect of wetting was maximal at 10–11 days. Behavioural observations suggest a drop in the time spent in the warmest section of the thermal gradient after five days and that the coldest part of the gradient (5°C) was hardly visited before 25 days of age. The sequence for attaining homeothermia in the partridge is thus comprised of an early development of significant thermogenesis from day 5 onwards, followed by a rapid increase in insulation around two weeks of age. Despite this fact, especially wet chicks strongly depend on parental heat in cold spells during the first three weeks of their life. The increase in body mass and the development of a water‐impermeable plumage enhance the cold resistance in older chicks.

Mate choice in the grey partridge,Perdix perdix: role of physical and behavioural male traits

The brown breast patch of the male grey partridge, the species' most conspicuous sexually dimorphic trait, was totally or partly bleached out, to test its influence on female preference. In mate-choice experiments, patch size (which was unaffected by early testosterone treatment) appeared to be unimportant: artificially and naturally bred females primarily selected males on the basis of their vocal performance. High rates of rusty-gate calls and certain features of their acoustic structure, usually undervalued in studies on non-oscine birds, were the main determinants of male success, with the morphological traits being of lesser importance.

Gray Partridge Winter Home Range and Use of Habitat in North Dakota

Gray partridge (Perdrix perdrix) appear to be able to tolerate more extenvive cereal grain farming than other upland gamebirds in the northern plains. However, information on gray partridge use of habitats in this ecosystem is necessary to understand effects of changing farming practices, especially during a season associated with severe mortality. We studied 100 (17 coveys) radio-tagged gray partridge during winters 1985-87 to determine home ranges, movements, and use of habitat in north-central North Dakota. Mean convex polygon home-range size was 116 ha and mean movement per day was 256 m (n = 17 coveys). For radio-tagged coveys (n = 16), cereal grains and sunflowers accounted for >80% of locations. Proportions of habitats found within convex polygon home ranges were not different from study area availability (P = 0.08); however, proportions of individual radiolocations were different from availability within convex polygon home ranges (P = 0.005). Among radiolocations, the order of relative use of habitat from most to least was sunflower, cereal grain, summer fallow, farmstead/wooded, road/roadside, idle/wetland, and hay/pasture. The most frequented habitats were widely available in the study area. Farmstead/wooded habitats are apparently not used as extensively as has been previously reported in North Dakota, and the deep-snow condition when farmstead/wooded habitats were selected was not common. The introduction of sunflowers to this cereal grain ecosystem apparently provides gray partridge an important new winter habitat

Population dynamics of the Grey Partridge Perdix perdix 1793–1993: monitoring, modelling and management

The longest available bag record of Grey Partridges Perdix perdix in Great Britain (1793–1993) reveals a collapse of stocks after 1952 despite considerable annual variation. The annual fluctuations were attributable largely to annual variations in chick survival rate. The Game Conservancy Trust's National Game Census revealed that chick survival rates averaged 49% before the introduction of herbicides and 32% once their use became widespread. On a study area in Sussex, where spring density declined from around 21 pairs per km2 in 1968 to under four pairs per km2 in 1993, annual chick survival rates averaged 28% with no demonstrable trend. The annual over‐winter “survival” rates in the area improved during 1968–1993, whereas brood production rates declined. Simulation modelling showed that a reduction in chick survival rate from 49% to 32% had little effect on spring stocks as long as nest predation was controlled but that stocks collapsed when nest predation control was relaxed. The effect of such a change in chick survival rate on population status was investigated by reference to 36 other studies in the literature. Amongst 20 studied populations which were stable, adjusting mean chick survival rates downwards produced demographic parameters characteristic of declining populations in all but two cases. Conversely, adjusting chick survival rates upwards for 16 declining populations made all but two stable. Diagnosing and remedying the causes of population change require a testable understanding of density‐dependent factors and compensatory processes, best approached by a combination of monitoring, modelling and management.

Testosterone Affects the Acoustic Structure of the Male Call in the Grey Partridge (Perdix Perdix)

The effects of testosterone (T) on the acoustic features of the rusty-gate call of the grey partridge, a non-oscine bird, were studied in 24 males kept in semi-natural conditions. Half of them were implanted subcutaneously with T propionate in Silastic tubes at 10 weeks of age, the remaining were sham operated as controls. After one month implanted males showed significantly higher T levels than controls, while treatment did not affect body size. Individual recordings of calls were analysed and accurate measurements were taken by a digital spectrograph. The duration of calls was significantly greater in T-males than in controls. A similar lengthening has been described in nature in spring, when plasma levels of androgens rise. The frequencies of the most intense portion of the call ranged more widely and had a lower minimum in T-males than in controls, suggesting an hormonal control on call system at the peripheral/central level. In conclusion T affects specific temporal and frequency features of the male calls. The relationship between T and call structure could enable females to assess quality and sexual motivation of their potential mates.

Habitat Relationships of the Pyrenean Gray Partridge

Summer habitat relationships of the pyrenean gray partridge (Perdix peridix hispaniensis) were studied in the northern Pyrenees Mountains (France). Six available habitat types were defined, and those selected or avoided were identified. The only habitat type significantly (P < 0.05) selected was at intermediate altitudes, on fairly steep south-exposed slopes, with a moderate cover of woody plants. Two habitat types were significantly avoided. One occurred at low altitudes on mowed plateaus colonized by low woody plants, and the other was at high altitudes on slopes free of low woody plants. We suggest applications of the work in a model that should lead to valid habitat recommendations for restoring partridge populations.

Hypobiosis of Trichostrongylus tenuis in experimentally infected grey partridges

Storage of infective larvae (L3) of Trichostrongylus tenuis at +4°C for six weeks before being given as single infections to grey partridges ( Perdix perdix) did not increase the proportion of worms subsequently found to be hypobiotic. However, after repeated infections, hypobiotic larvae were numerous. Three infections given over three weeks resulted not only in the presence of many hypobiotic larvae, but also in the coincident loss of most adult worms. This indication of the role of immunity in the production of hypobiosis in grey partridges suggests that this species is not a good model for trichostrongylosis in red grouse ( Lagopus lagopus scoticus).

Research Note: Evaluation of the Productivity of Two Strains of Gray Partridge

Two strains of gray partridge (Perdix perdix) were evaluated for productivity and field performance for the put-and-take hunting industry. Total egg production and hatchability of fertilized eggs did not differ (P > .05) between strains or among age classes. However, Danish birds had higher (P < .05) overall production of chicks than did McGraw strain birds due to higher fertility of 1-yr-old breeders. There were no apparent differences in flushing behavior or flight patterns between strains, but the Danish strain was better suited to put-and-take hunting because hunters were more effective in shooting released birds of this strain.