Effects of supplementary feeding on territoriality\ breeding success

Journal of Applied Ecology 0888\ 25\ 036Ð045

Effects of supplementary feeding on territoriality\ breeding success and survival of pheasants A[N[ HOODLESS\ R[A[H[ DRAYCOTT$\ M[N[ LUDIMAN% and P[A[ ROBERTSON& The Game Conservancy Trust\ Fordingbridge\ Hampshire\ SP5 0EF\ UK^ and %Harper Adams Agricultural College\ Newport\ Shropshire\ TF09 7NB\ UK

Summary 0[ The e}ects of supplementary food in spring on subsequent pheasant breeding in an intensively farmed area in southern England were assessed by a large!scale\ rep! licated _eld experiment[ 1[ Territorial cock pheasants were counted in April\ and the breeding success and survival of radio!tagged hens were monitored in six 0!km1 plots during 0883 and 0884[ Total numbers of young reared and post!breeding pheasant densities were found by August counts[ In 0883\ three randomly selected plots were supplied with wheat grains via hoppers along woodland edges and hedgerows[ The other three plots acted as controls and the treatments were reversed in 0884[ 2[ The density of cock territories increased signi_cantly in food!supplemented plots "33 2 7 km−1# in relation to control plots "18 2 7 km−1#\ and the presence of hoppers signi_cantly a}ected the locations of territories[ However\ similar proportions of territorial males acquired harems in the control and food!supplemented plots[ Hen density did not increase and\ consequently\ the mean harem size was signi_cantly lower with supplementary feeding[ 3[ Hens given supplementary food did not nest earlier and the number of nests initiated\ clutch sizes and the proportion of successful nests did not di}er signi_cantly from those of controls[ However\ hens supplied with supplementary food re!nested signi_cantly more quickly following the loss of a nest or brood[ 4[ Radio!tagged hens did not rear signi_cantly more young with supplementary feed! ing[ Hen survival was unchanged and post!breeding pheasant densities were no higher[ 5[ On present evidence\ spring feeding cannot be advocated as a management tech! nique to improve the breeding success of pheasants surviving the winter[ Key!words] Phasianus colchicus\ intensive agriculture\ spring supplementary feeding\ territoriality\ breeding success[ Journal of Applied Ecology "0888# 25\ 036Ð045

Introduction Food supply often limits some aspects of reproduction and occasionally survival in birds "Martin 0876#\ as is

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particularly apparent in seabirds "Sa_na et al[ 0877^ Monaghan et al[ 0878^ Hamer\ Furness + Caldow 0880^ Bolton\ Houston + Monaghan 0881^ Pons + Migot 0884^ Suddaby + Ratcli}e 0886#[ The most

Correspondence] Dr A[ Hoodless\ The Game Conservancy Trust\ The Gillett\ Forest!in!Teesdale\ Barnard Castle\ County Durham DL01 9HA[ Tel[ 90722Ð511197[ Fax] 90722Ð511232[ E!mail] ahoodlessÝgame!conservancy[org[uk  Present address] The Game Conservancy Trust\ The Gillett\ Forest!in!Teesdale\ Barnard Castle\ County Durham\ DL01 9HA\ UK[ $ Present address] The Game Conservancy Trust\ Ash_eld Green Farm\ Wickhambrook\ Newmarket\ Su}olk\ CB7 7UZ\ UK[ % Present address] Game Conservancy Limited\ Fordingbridge\ Hampshire\ SP5 0EF\ UK[ & Present address] Central Science Laboratory\ Sand Hutton\ York\ YO3 0LZ\ UK[

036

037 Effects of supplementary feeding on pheasants

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common response to additional food in supple! mentation experiments on birds has been earlier breeding "Boutin 0889#[ An earlier and:or longer breeding season has been demonstrated in raptors "Newton + Marquiss 0870^ Dijkstra et al[ 0871#\ cor! vids "Yom!Tov 0863^ Hogstedt 0870^ Hochachka + Boag 0876^ Dhindsa + Boag 0889# and passerines "Kallander 0863^ Bromssen + Jansson 0879^ Ewald + Rohwer 0871^ Davies + Lundberg 0874^ Arcese + Smith 0877#\ but additional food led to an increase in clutch size in only three of these experiments[ If nest survival is inversely related to the time spent foraging by the parent bird during incubation\ sup! plementary feeding might be expected to reduce nest loss to predators\ but there is little evidence for this from studies of altricial species "Yom!Tov 0863^ Hog! stedt 0870^ Hochachka + Boag 0876^ Dhindsa + Boag 0889# with the exception of one study "Richner 0881#[ Chick survival\ however\ was increased in all of these studies[ There is very little evidence in altricial species for more nesting attempts or quicker re!nesting as a result of supplementary feeding "Arcese + Smith 0877#[ The e}ect of additional food on male territoriality has received little attention\ but the density of ter! ritorial male red!winged blackbirds Agelaius pho! eniceus has been shown to increase in response to an increased density of feeders "Ewald + Rohwer 0871#[ In many polygynous birds\ territory quality is an important determinant of male success "Orians 0858^ Garson\ Pleszczynska + Holm 0870# and this could potentially be a}ected by food availability[ Few studies have examined the e}ects of food limi! tation on reproductive success in precocial species\ but there is evidence that egg quality and brood size in some grouse species are related to maternal nutrition "Moss\ Watson + Parr 0864^ Beckerton + Middleton 0871^ Moss + Watson 0873#[ Di}erences in the weight of lesser snow geese Chen caerulescens on arrival on their breeding grounds have been shown to be cor! related with follicle development and hence potential clutch size "Ankney + MacInnes 0867#[ The only experimental manipulations involving precocial spec! ies have been studies showing that heather Calluna vulgaris enrichment with fertilizer can increase brood size and breeding density in red grouse Lagopus lag! opus scoticus "Watson + O|Hare 0868^ Watson\ Moss + Parr 0873#[ Relative egg size\ yolk content and caloric density increase with precocity "Rahn\ Paganelli + Ar 0864^ Carey\ Ralin + Parisi 0879# and therefore food sup! plementation is more likely to a}ect clutch size and egg quality in precocial birds[ Because the daily energy expenditure for the production of clutches is greater in precocial birds than altricial species "King 0862#\ supplementary feeding might be expected to produce a bigger di}erence in the time taken to re!nest and the number of re!nesting attempts in precocial species[ Precocial species are able to deplete their energy

reserves much more during egg production and incu! bation than altricial species\ because they do not need energy to feed their young after hatching "Martin 0876#[ For this reason\ food supplementation is more likely to increase nest survival during incubation in precocial than in altricial species[ In this paper\ these hypotheses are examined by means of the _rst large!scale\ replicated _eld experi! ment on a precocial bird[ Wild pheasant Phasianus colchicus L[ populations in Britain are supplemented annually by the release of large numbers of hand! reared birds "Robertson + Dowell 0889#[ The breed! ing success and survival of hand!reared pheasants is known to be poor "Hill + Robertson 0877a^ Brittas et al[ 0881^ Leif 0883# and we suggest that this is partly due to poor nutrition[ Pheasants feed in agricultural habitats\ which have been subjected to increasingly intensive management during the last 29 years[ This has included a shift from spring!sown to autumn!sown cereals\ increased herbi! cide application and more e.cient harvesting "Stoate 0885#[ As a result\ cereal _elds now contain very low densities of weed seeds and waste cereal grains "Dray! cott et al[ 0886#\ which are an important component of pheasant diet in spring "Hoodless et al[\ in press#[ A study of pheasant diet on the area used for the present experiment revealed that the birds obtained very few weed seeds or cereal grains under natural conditions "Hoodless et al[\ in press#[ We have demon! strated that the provision of supplementary wheat in spring improved the body condition of female phea! sants prior to incubation "Draycott et al[ 0887#[ These factors make the pheasant a useful species for the study of the e}ects of supplementary feeding[ It also has polygynous mating\ enabling the e}ect of sup! plementary feeding on territory density and harem size to be measured[

Methods STUDY AREA

Fieldwork was done during 0883 and 0884 at Claren! don Park Estate\ Wiltshire\ UK "40>93?N\ 0>33?W#[ The estate covers ¼19 km1\ used mainly for arable farming[ Woodland consists predominantly of a large block "259 ha# of deciduous and conifer stands in the centre[ The _elds in the north!western half are inter! spersed by a network of shelterbelts[ The gamekeepers rear their own pheasant poults\ which are transferred to release pens in late July at about 5 weeks old[ The birds are fed wheat via hoppers in the woods until February[ There are few\ if any\ truly wild pheasants\ and naturalized birds "those surviving two shooting seasons following release# comprise about 09) of the population[ Foxes Vulpes vulpes L[ are shot but there is considerable immigration from outside[ Corvids are controlled\ but there is no mustelid trapping[ No con! servation headlands "Sotherton 0880# or other

038 A[N[ Hoodless et al[

speci_cally designed brood!rearing habitats are incor! porated into the farming[ The study was done on six 0!km1 plots\ located so that each was at least 249 m from its nearest neighbour "Fig[ 0#[ Supplementary food was provided in three randomly selected plots\ with three experimental rep! licates and three control replicates in each year[ In 0884\ the control and food!supplemented plots were switched to control for between!plot habitat di}er! ences[ Movement of pheasants between plots was neg! ligible\ as over the 1 years only three out of 190 radio! tagged females moved from one plot to a di}erent plot[

PROVISION OF SUPPLEMENTARY FOOD

Whole wheat grains were provided for pheasants in 14!L slit hoppers[ Between 37 and 47 hoppers were placed along woodland edges and hedgerows in each of the three supplemented plots\ such that they were

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¼49 m apart[ The hoppers were opened in early March and were _lled at 03Ð15!day intervals until mid!June[ Direct observations and dietary analysis of pheasants in the supplemented plots con_rmed that they regularly visited the hoppers "Hoodless et al[\ in press#[ Observations of radio!tagged hens indicated that they continued to feed from hoppers during incu! bation[ Inevitably\ some wheat was taken by non! target species but\ with very few exceptions\ hoppers were never empty[ Wheat was chosen as the supplementary food because it is the most commonly used winter food on estates with reared pheasants and does not become compacted in hoppers when damp\ unlike com! mercially produced feeds[ Wheat has a high carbo! hydrate content and is therefore a good source of energy for pheasants\ but lacks certain amino!acids and calcium which are essential in a balanced diet "Wise 0883#[ Pheasants in supplemented plots did not feed exclusively on the wheat and ingested su.cient

Fig[ 0[ Location of experimental plots at Clarendon Park Estate\ Wiltshire[ Three plots were food!supplemented and three acted as controls during spring 0883\ and treatments were switched in 0884[ Arable and grass _elds are shown in white and woodland is stippled[

049 Effects of supplementary feeding on pheasants

green shoots\ weed seeds and invertebrates to account for their other nutrient requirements "Hoodless et al[\ in press#[

COCK TERRITORIES AND HAREMS

The locations of male pheasant territories and the numbers of territorial males\ non!territorial males\ and females were determined from three to six com! plete counts in each plot according to the method of Robertson et al[ "0882#[ The density of territories along woodland edges has varied between years on this study site in relation to the crop type in the neigh! bouring _eld\ densities being high when the crop com! prised wheat or barley\ and low when grass "Robert! son et al[ 0882#[ The results of this previous study were used to correct for changes in crop types between years and their e}ects on within!plot territory densities[ The number of territories per plot was also corrected for sighting probability "the likelihood of a particular bird being seen during a count# according to the number of counts[ Female density was estimated using the same corrections for sighting probability as for ter! ritorial males "Robertson et al[ 0882#[ Territorial cocks were de_ned as having acquired harems if at least one hen was associated with them during any of the _rst three counts in April[ Harem size was rec! orded as the maximum number of hens seen within 14 m of the cock[

HEN SURVIVAL AND BREEDING SUCCESS

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Dates of nest establishment\ the outcome of nesting attempts and the timing of mortality in hens were determined by radio!tracking[ During February and early March\ 03Ð08 females per plot were caught in baited traps and _tted with two!stage 06!g necklace radio!tags "Biotrack Ltd\ Wareham\ Dorset\ UK#[ The birds were located using TR1 receivers "Telonics\ Arizona\ USA# and hand!held\ three!element Yagi antennas[ Hens not moving between successive radio! locations were approached until it could be seen whether they were nesting or dead[ Samples of _ve hens per plot in 0883 and three per plot in 0884 were tracked intensively during April for analysis of home range as part of another study "Hoodless et al[\ in press#[ The remaining birds were located during 17Ð29 March and then twice a week during 15 AprilÐ04 August[ For this reason\ analyses of the number of nesting attempts and of nesting suc! cess are based on the number of hens alive on 29 April[ Among the intensively tracked hens\ 6) had nests that were predated or deserted before 29 April\ and the number of nesting attempts per plot has been adjusted accordingly[ Nests were visited at 1Ð2!day intervals and clutch sizes recorded when females were absent[ For analysis\ clutch sizes were corrected for laying date\ as the mean clutch size of pheasants declines during the breeding

season "Robertson 0880#[ Because some nests were not detected during egg!laying\ the timing of nesting was analysed using estimated dates of the start of incubation[ The start date was back!calculated from the hatching date where known\ assuming a 14!day incubation period "Cramp + Simmons 0879^ Hill + Robertson 0877b#[ In other cases\ it was calculated by adding 0=3 days per additional egg laid before the start of incubation "Robertson 0880# to the date of the last pre!incubation nest check[ Where possible\ the cause of nest failure was determined and the number of chicks hatched from successful nests was recorded[ Broods were located daily and brood size was deter! mined when the chicks were 09 and 19 days old\ the hen being ~ushed if necessary to obtain an accurate count[ Total numbers of young reared to the age of at least 09 days and total post!breeding pheasant densities were determined as the maximum from three counts in each plot at dawn and dusk during late August[ No correction for sighting probability has been deter! mined for pheasant counts at this time of year\ but there was relatively little variation between counts "coe.cients of variation 8Ð19)#[

STATISTICAL ANALYSIS

As supplementary food was supplied via hoppers rather than administered directly to each pheasant\ analyses were based on mean values for each plot[ Because the sample size for some variables di}ered between plots\ means were weighted by sample size to re~ect their di}erent accuracies[ Data were analysed using a two!way analysis of variance with feeding as a repeated!measures variable and year as an inde! pendent variable[ Percentages were transformed to angles "arcsin zp# and numbers log!transformed\ where necessary\ to achieve normality[ Statistics were computed using SYSTAT 4=9 "Wilkinson 0889#[ Mean values are presented with standard errors throughout[

Results TERRITORIALITY

The mean percentage of cocks that were territorial was signi_cantly higher when plots were food!sup! plemented "Table 0#[ There was also a signi_cant increase in territory density\ the mean di}erence in the number of pheasant territories being 03=6 2 7=1 territories km−1 "Table 0#[ The presence of hoppers a}ected the location of male territories\ because sig! ni_cantly more territories were centred on hopper positions with supplementary feeding "Table 0#[

HAREMS OF TERRITORIAL MALES

Female density was not increased with supplementary feeding\ and harem acquisition did not di}er between

040 A[N[ Hoodless et al[

Table 0[ Means\ standard errors and two!way repeated!measures analysis of variance data on territoriality\ hen density and harems in six 0!km1 plots "three controls and three food!supplemented# during 0883 and 0884

Cock territoriality ) cocks territorial Number of territories ) territories centred on hopper positions Harem acquisition and harem size Number of hens ) territorial cocks with at least one hen Mean harem size

Feeding

Year

Control

Supplementary food

Feeding × Year

F0\3

P

F0\3

P

F0\3

P

34=2 2 4=0 18=2 2 6=6 48=3 2 8=0

51=8 2 1=4 33=0 2 7=3 79=5 2 2=8

07=49 7=19 7=35

9=902 9=935 9=933

9=93 9=11 0=47

9=733 9=551 9=167

1=09 1=37 9=93

9=110 9=080 9=747$

62=4 2 05=7 62=5 2 6=2

48=6 2 7=6 55=0 2 3=2

0=97 0=32

9=247 9=186

9=94 9=06

9=728 9=693

0=30 2=01

9=290 9=041$

2=53 2 9=50

1=32 2 9=08

8=50

9=925

1=26

9=088

4=69

9=964

 Data log!transformed[ $ Data arcsin!transformed[

treatments\ as the mean percentages of territorial males with at least one female were similar in the control and food!supplemented situations "Table 0#[ The mean harem size of cocks with hens was sig! ni_cantly lower with supplementary feeding "Table 0#[ There was no indication that hens were more equally distributed amongst cocks with supplementary feed! ing "data pooled for all plots^ x16  09=75\ P  9=034#[ TIMING AND NUMBER OF NESTING ATTEMPTS

Mean dates of the start of incubation were similar in the control plots and those with supplementary food "Table 1#[ Unmarked hens killed in the control and

food!supplemented plots at the end of April "Draycott et al[ 0887# had well developed follicles in their ovaries and 81) "n  28# had ovarian scars[ The proportions of hens alive on 29 April that nested in the control and food!supplemented plots did not di}er signi_cantly "Table 1#[ There were no signi_cant di}erences between treat! ments in the number of nests initiated per female or the number of replacement clutches laid following nest or brood loss "Table 1#[ Data on the time taken to lay replacement clutches were available only for some plots[ The few data for individual hens under each treatment suggest that they re!nested more quickly when given supplementary food\ with the median

Table 1[ Means\ standard errors and two!way repeated!measures analysis of variance data on nesting\ hen survival and post! breeding density in six 0!km1 plots "three controls and three food!supplemented# during 0883 and 0884 Feeding P

F0\3

P

F0\3

P

4 May 2 8=9 d 56=1 2 7=1 0=99 2 9=03 9=22 2 9=96

9=97 9=03 1=05 2=49

9=682 9=618 9=104 9=024

1=07 1=87 9=13 0=28

9=103 9=059 9=549 9=292

3=56 1=63 1=12 9=99

9=986 9=062$ 9=109 9=858

09=6 2 2=3 07=9 2 6=3 7=45 2 2=57

00=5 2 1=1 13=5 2 09=0 08=33 2 6=36

9=33 9=38 0=15

9=434 9=411 9=213

9=99 9=59 9=57

9=844 9=370 9=344

3=07 3=13 1=86

9=009 9=098$ 9=059

1=07 2 9=88

2=77 2 0=73

9=97

9=683

3=14

9=097

9=91

9=895

1=06 2 9=64

5=72 2 1=03

4=09

9=976

0=31

9=188

0=16

9=212

71=9 2 4=8 20=2 2 6=5 12=9 2 3=5

9=20 9=41 9=18

9=597 9=400 9=506

5=46 9=21 9=55

9=951 9=592 9=353

9=79 9=99 2=01

9=310$ 9=864$ 9=041

Timing and number of nesting attempts Start of incubation 3 May 2 6=7 d ) hens that nested 45=8 2 09=8 Nests initiated per hen 9=58 2 9=01 Replacement nests per hen 9=01 2 9=95

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Hen survival and post!breeding pheasant density ) hens alive on 29 April 72=7 2 4=8 ) hens alive on 04 August 13=0 2 5=3 Post!breeding density 13=4 2 5=3  Data log!transformed[ $ Data arcsin!transformed[

Feeding × Year

F0\3

Control

Hen breeding Clutch size ) successful nests Number of chicks hatched per plot Chicks reared to 09 days per plot Total young reared per plot

Year

Supplementary food

041 Effects of supplementary feeding on pheasants

number of days between the date of nest or brood loss and the _rst!egg date of the replacement nest being 20 in the control plots and 04 in those with supple! mentary feeding "MannÐWhitney U2\06  36=9\ P  9=912#[

HEN PRODUCTIVITY

There was no di}erence in mean clutch size between treatments "Table 1#[ No conclusion could be drawn about whether supplementary feeding led to improved hatchability of eggs because sample sizes were too small ðcontrol 58=9 2 1=7) "n  2#\ supplementary feeding 66=7 2 4=2) "n  09#\ t00  9=87\ P  9=238Ł[ The proportions of successful nests "those from which at least one chick hatched# were similar in the control and food!supplemented plots "Table 1#[ Fox and corvid predation accounted for most nest losses "27) and 29)\ respectively#[ The proportions of failed nests taken by these predators did not di}er sig! ni_cantly between treatments "data arcsin!trans! formed\ fox predation] feeding P  9=280\ year P  9=091\ feeding × year P  9=021^ corvid pre! dation] feeding P  9=818\ year P  9=796\ feeding × year P  9=690#[ Rates of desertion among failed nests were similar in control and food!supplemented plots "06=1 2 7=5) and 02=5 2 5=7)\ respectively\ data arcsin!transformed\ feeding P  9=374\ year P  9=224\ feeding × year P  9=549#[ The mean number of chicks hatched per hen alive on 29 April did not di}er signi_cantly between treat! ments "control 9=74 2 9=27\ supplementary feeding 0=67 2 9=56\ data log!transformed\ feeding P  9=231\ year P  9=361\ feeding × year P  9=217#[ Neither was there a signi_cant di}erence in the absolute num! bers of chicks hatched\ corrected for the number of hens tagged\ between treatments "Table 1#[ Chick mortality was high and there was no di}erence between treatments in the numbers of chicks reared to 09 days by radio!tagged hens "Table 1#[ Only four of these chicks survived to ~edging[ Although the total numbers of reared young per plot seen during autumn counts were very low\ the di}erence between treat! ments was close to signi_cance "Table 1#[

HEN SURVIVAL AND POST!BREEDING PHEASANT DENSITY

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The mean proportions of hens surviving until 29 April were similar in the control and food!supplemented plots\ as were the proportions surviving to 04 August "Table 1#[ The main period of mortality in each case occurred between mid!April and the end of May and 78) of all deaths were attributed to fox predation[ There was no di}erence in post!breeding pheasant densities between treatments "Table 1#[

Discussion COCK TERRITORIES AND HAREMS

Robertson et al[ "0882# concluded that the preference of territorial cocks for edges bordering arable _elds was due to increased availability of growing shoots and seeds[ The current experiment has shown that food availability does indeed in~uence the locations of cock pheasant territories and territory density[ Similarly\ Ewald + Rohwer "0871# found that an increased density of feeders led to an increased density of territorial male red!winged blackbirds\ and the fre! quency of defence displays in hummingbirds has been shown to be related to resource availability within territories "Ewald + Carpenter 0867^ Ewald + Orians 0872^ Tamm 0874#[ Our _nding that cock breeding success\ as measured by harem acquisition and harem size\ was not improved by supplementary feeding is in agreement with previous studies which concluded that male qual! ity is more important than territory quality in phea! sants "Ridley + Hill 0876^ Goransson et al[ 0889^ Grahn\ Goransson + von Schantz 0882a\b#[ Since food supplementation in our experiment did not a}ect the density of breeding hens\ it can be inferred that food availability has little in~uence on the dispersal of hens from their winter ~ocks in late March and early April[

NESTING AND BREEDING SUCCESS

There is good evidence for earlier laying in a range of bird species when given supplementary food "Boutin 0889# and the fact that food availability may a}ect the timing of nesting in pheasants has been demon! strated in experiments that restricted diet "Breiten! bach\ Nagra + Meyer 0852^ Gates + Woehler 0857^ Barrett + Bailey 0861#[ These workers concluded that pheasants will not commence egg!laying until they have built up large fat deposits[ The reason why there was no di}erence in the start of incubation between treatments in the present study may be that pheasants in all plots were fed during the winter[ Despite the fact that the fat deposits of hens in control plots declined by 46) between late February and the end of April "Draycott et al[ 0887#\ they were probably still su.cient to enable the hens to incubate their _rst clutches[ The similar\ low rates of nest desertion under both treatments and the absence of deaths through emaciation suggest that hens in control plots were never in exceptionally poor condition[ The reduction in the time taken by food!supple! mented hens to lay replacement clutches and the size of the di}erence in the number of replacement clutches laid between treatments suggest that\ in natural con! ditions\ hens may have di.culty meeting the energetic requirements of nesting once they have depleted their reserves by incubating one clutch[ Wise "0883# found

042 A[N[ Hoodless et al[

Table 2[ The e}ects of management techniques commonly implemented for pheasants Woodland manipulation Planting and felling of woods Size and shape of woods

Shrubby cover within woods Shrubby cover at wood edges Winter feeding

Used to hold and redistribute pheasants for driven shooting\ but may mitigate losses of natural foods caused by modern agriculture[ Higher winter pheasant densities found in woods where food provided "Robertson\ Woodburn + Hill 0882#[ Estates with winter feeding have higher breeding densities "Robertson et al[ 0882#\ but there is no evidence that it results in improved over!winter survival[

Spring feeding

Increased density of cock territories "this study#[ Maintains fat reserves of hens prior to incubation "Draycott et al[ 0887#[ Hens re!nest more quickly following nest or brood loss "this study#[ More replacement nests laid and chicks hatched "this study#[

Farm management Cover crops Winter stubble Cropping pattern Conservation headlands

Managed set!aside

Predation control Corvids

Foxes

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The density of territorial cocks is highest when woods comprise about 29) of the landscape "Robertson 0881#[ Winter pheasant density is higher in small woods and increases in relation to the amount of woodland edge "Robertson\ Woodburn + Hill 0882#[ It can be increased by manipulating woodland shape and introducing wide rides[ Increased winter density "Robertson 0874^ Robertson\ Woodburn + Hill 0882#[ Increased breeding density "Lachlan + Bray 0865^ Robertson et al[ 0882#[

Provide winter food and shelter\ but no evidence for increased survival of adult birds[ Provides winter food[ Territorial cock density is higher at woodland edges adjoined by arable crops as opposed to grass "Robertson et al[ 0882#[ Improved chick survival because chicks are dependent on insect availability in cereal _elds\ which is in~uenced by the level of pesticide use "Hill 0874^ Sotherton + Robertson 0889^ Sotherton 0880#[ Provides spring food because it contains more weed seeds and waste cereal grains in early spring than arable crops "Draycott et al[ 0886#[ Density of territorial cocks higher along woodland edges bordering set!aside than edges bordering arable crops "Man½osa 0883#[ Intensively used by hens with broods "Boatman 0887#[

Reduced egg losses during laying indicated from comparison of BTO nest records with records from keepered estates "Robertson 0880#[ Increased hatching success and increased post!breeding population size\ as a result of improved chick survival\ when crows and small carnivores controlled "Chesness\ Nelson + Longley 0857#[ Increased post!breeding population size\ as a result of improved juvenile and adult survival "Jensen 0869^ Trautman\ Frederickson + Carter 0863#[

that despite almost total depletion of fat reserves and substantial loss of muscle mass in penned feed!restric! ted pheasants between March and mid!May\ egg pro! duction did not decline until late April[ In the wild\ most hens will have started laying their _rst clutches by this time and since the majority of the clutch sizes recorded in the present study were from _rst nests\ it is not surprising that there was no di}erence between treatments[ The fact that there was no improvement in nest survival is surprising\ given that Hoodless et al[ "in press# found that hens given supplementary food spent less time feeding at dawn and dusk[ However\ they did not record nest attendance of individual hens\ so it cannot be concluded that nests in the supplemented plots were left exposed for shorter periods[ Although not statistically signi_cant\ the size of the di}erence in the number of chicks hatched between treatments was such that an appreciable improvement in productivity

might be achieved with supplementary feeding on the scale of an entire estate[

HEN SURVIVAL

The rate of hen mortality was highest during incu! bation\ when hens often sit very still and are probably at their most vulnerable to foxes[ The improvement in body condition in April among hens given supple! mentary food "Draycott et al[ 0887# did not confer any signi_cant advantage in subsequent survival rate[ This is in agreement with the _nding that there was no di}erence in the breeding season survival of willow ptarmigan Lagopus lagopus albus and L[ l[ alexandrae in good and poor condition\ as measured by spring body mass "Robb\ Martin + Hannon 0881#[ However\ these workers found that the return rate in the fol! lowing year was lower for adult females in poor con! dition[

043 Effects of supplementary feeding on pheasants

No experimental studies have examined the survival of full!grown birds given supplementary food in the breeding season\ but food addition did not improve the summer survival of adult deermice Peromyscus maniculatus\ woodmice Apodemus sylvaticus or white! footed mice Peromyscus leucopus "Fordham 0860^ Flowerdew 0861^ Hansen + Batzli 0867\ 0868#[ Winter survival of passerines is improved with supplementary food "Smith et al[ 0879^ Van Balen 0879^ Jansson\ Ekman + Bromssen 0870^ Brittingham + Temple 0877^ Desrochers\ Hannon + Nordin 0877#\ but the scale of the response depends on the availability of natural food at the time of supplementation "Van Balen 0879#[

MANAGEMENT IMPLICATIONS

Clarendon Park\ the estate used for the present study\ is typical of many estates today\ where the emphasis is on arti_cially rearing pheasants rather than max! imizing wild production[ Consequently\ game man! agement tends to consist primarily of woodland manipulation\ planting cover crops and winter feed! ing[ This helps to retain high winter densities of phea! sants for shooting but fails to help the breeding popu! lation other than by increasing the availability of potential territories "Table 2#[ In many cases there is some control of foxes and corvids\ but during the crucial period when wild and naturalized hens are nesting and rearing broods\ gamekeepers are pre! occupied with hatching and rearing birds indoors[ In most cases\ this situation has arisen due to reduced viability of wild pheasant populations as a result of agricultural intensi_cation[ On the present evidence\ spring feeding alone can! not be advocated as a management technique to improve pheasant productivity\ although it does result in females being in better condition prior to egg!laying "Draycott et al[ 0887#[ To ensure recruitment into the autumn population\ brood!rearing habitats\ such as conservation headlands or set!aside strips comprised of cereal mixtures\ must be incorporated to provide the arthropod biomass required for good chick sur! vival "Hill 0874^ Sotherton 0887#[ The combination of spring feeding and suitable brood!rearing habitat might provide a method of increasing pheasant pro! ductivity in the wild and an opportunity for shoot managers to scale down hand!rearing operations[

Acknowledgements

Þ 0888 British Ecological Society\ Journal of Applied Ecology\ 25\ 036Ð045

This study was funded by Southern Counties Agri! cultural Traders and The Game Conservancy Trust[ We are grateful to A[ Christie!Miller for allowing us to work at Clarendon Park Estate and to the game! keepers\ R[ Perks and P[ Osborne\ and the farm manager\ R[ Price\ for their willing co!operation[ We thank Drs N[ Aebischer\ J[ Carroll\ N[ Sotherton and two anonymous referees for statistical advice and con!

structive criticism of the manuscript[ F[ Pirrami pro! duced the _gure[

References Ankney\ C[D[ + MacInnes\ C[D[ "0867# Nutrient reserves and reproductive performance of female lesser snow geese[ Auk\ 84\ 348Ð360[ Arcese\ P[ + Smith\ J[N[M[ "0877# E}ects of population density and supplemental food on reproduction in song sparrows[ Journal of Animal Ecology\ 46\ 008Ð025[ Barrett\ M[W[ + Bailey\ E[D[ "0861# In~uence of met! abolizable energy on condition and reproduction of phea! sants[ Journal of Wildlife Management\ 25\ 01Ð12[ Beckerton\ P[R[ + Middleton\ A[L[A[ "0871# E}ects of diet! ary protein levels on ru}ed grouse reproduction[ Journal of Wildlife Management\ 35\ 458Ð468[ Boatman\ N[ "0887# Wild game conservation on arable land Ð towards a better future[ The Game Conservancy Trust Review\ 18\ 55Ð58[ Bolton\ M[\ Houston\ D[ + Monaghan\ P[ "0881# Nutritional constraints on egg formation in the lesser black!backed gull] an experimental study[ Journal of Animal Ecology\ 50\ 410Ð421[ Boutin\ S[ "0889# Food supplementation experiments with terrestrial vertebrates] patterns\ problems\ and the future[ Canadian Journal of Zoology\ 57\ 192Ð119[ Breitenbach\ R[P[\ Nagra\ C[L[ + Meyer\ R[K[ "0852# E}ect of limited food intake on cyclic annual changes in ring! necked pheasant hens[ Journal of Wildlife Management\ 16\ 13Ð25[ Brittas\ R[\ Marcstrom\ V[\ Kenward\ R[E[ + Karlbom\ M[ "0881# Survival and breeding success of reared and wild ring!necked pheasants in Sweden[ Journal of Wildlife Man! agement\ 45\ 257Ð265[ Brittingham\ M[C[ + Temple\ S[A[ "0877# Impacts of sup! plemental feeding on survival rates of black!capped chickadees[ Ecology\ 58\ 470Ð478[ Bromssen\ A[V[ + Jansson\ C[ "0879# E}ects of food addition to willow tit Parus montanus and crested tit P[ cristatus at the time of breeding[ Ornis Scandinavica\ 00\ 062Ð067[ Carey\ C[\ Ralin\ H[ + Parisi\ P[ "0879# Calories\ water\ lipid and yolk in avian eggs[ Condor\ 71\ 224Ð232[ Chesness\ R[A[\ Nelson\ M[M[ + Longley\ W[H[ "0857# The e}ect of predator removal on pheasant reproductive success[ Journal of Wildlife Management\ 21\ 572Ð586[ Cramp\ S[ + Simmons\ K[E[L[\ eds[ "0879# The Birds of the Western Palearctic\ Vol[ 1[ Oxford University Press\ Oxford[ Davies\ N[B[ + Lundberg\ A[ "0874# The in~uence of food on time budgets and timing of breeding of the dunnock Prunella modularis[ Ibis\ 016\ 099Ð009[ Desrochers\ A[\ Hannon\ S[J[ + Nordin\ K[E[ "0877# Winter survival and territory acquisition in a northern population of black!capped chickadees[ Auk\ 094\ 616Ð625[ Dhindsa\ M[S[ + Boag\ D[A[ "0889# The e}ect of food sup! plementation on the reproductive success of black!billed magpies Pica pica[ Ibis\ 021\ 484Ð591[ Dijkstra\ C[\ Vuursteen\ L[\ Daan\ C[ + Masman\ D[ "0871# Clutch size and laying date in the kestrel Falco tinnunculus] e}ect of supplementary food[ Ibis\ 13\ 109Ð102[ Draycott\ R[A[H[\ Butler\ D[A[\ Nossaman\ J[J[ + Carroll\ J[P[ "0886# Availability of weed seeds and waste cereals to birds on arable _elds during spring[ 0886 Brighton Crop Protection Conference\ pp[ 0044Ð59[ British Crop Pro! tection Council\ Farnham[ Draycott\ R[A[H[\ Hoodless\ A[N[\ Ludiman\ M[N[ + Robertson\ P[A[ "0887# E}ects of spring feeding on body condition of captive!reared ring!necked pheasants in

044 A[N[ Hoodless et al[

Þ 0888 British Ecological Society\ Journal of Applied Ecology\ 25\ 036Ð045

Great Britain[ Journal of Wildlife Management\ 51\ 446Ð 452[ Ewald\ P[W[ + Carpenter\ F[L[ "0867# Territorial responses to energy manipulations in the Anna hummingbird[ Oec! ologia\ 20\ 166Ð181[ Ewald\ P[W[ + Orians\ G[H[ "0872# E}ects of resource depression on use of inexpensive and escalated aggressive behavior] experimental tests using Anna hummingbirds[ Behavioural Ecology and Sociobiology\ 01\ 84Ð090[ Ewald\ P[W[ + Rohwer\ S[ "0871# E}ects of supplemental feeding on timing of breeding\ clutch!size and polygyny in red!winged blackbirds Agelaius phoeniceus[ Journal of Animal Ecology\ 40\ 318Ð349[ Flowerdew\ J[R[ "0861# The e}ect of supplementary food on a population of wood mice "Apodemus sylvaticus#[ Journal of Animal Ecology\ 30\ 442Ð455[ Fordham\ R[A[ "0860# Field populations of deermice with supplemental food[ Ecology\ 41\ 027Ð035[ Garson\ P[J[\ Pleszczynska\ W[K[ + Holm\ C[H[ "0870# The {polygyny threshold| model] a reassessment[ Canadian Journal of Zoology\ 48\ 891Ð809[ Gates\ J[M[ + Woehler\ E[E[ "0857# Winter weight loss related to subsequent weights and reproduction in penned pheasant hens[ Journal of Wildlife Management\ 16\ 123Ð 136[ Goransson\ G[\ von Schantz\ T[\ Froberg\ I[\ Helgee\ A[ + Wittzell\ H[ "0889# Male characteristics\ viability\ and harem size in the pheasant\ Phasianus colchicus[ Animal Behaviour\ 39\ 78Ð093[ Grahn\ M[\ Goransson\ G[ + von Schantz\ T[ "0882a# Spac! ing behaviour of male pheasants\ Phasianus colchicus\ in relation to dominance and mate acquisition[ Animal Behaviour\ 34\ 82Ð092[ Grahn\ M[\ Goransson\ G[ + von Schantz\ T[ "0882b# Ter! ritory acquisition and mating success in pheasants\ Pha! sianus colchicus] an experiment[ Animal Behaviour\ 35\ 610Ð629[ Hamer\ K[C[\ Furness\ R[W[ + Caldow\ R[W[G[ "0880# The e}ects of changes in food availability on the breeding ecology of great skuas Catharacta skua in Shetland[ Jour! nal of Zoology\ 112\ 064Ð077[ Hansen\ L[P[ + Batzli\ G[O[ "0867# The in~uence of food availability on the white!footed mouse] populations in iso! lated woodlots[ Canadian Journal of Zoology\ 45\ 1429Ð 1430[ Hansen\ L[P[ + Batzli\ G[O[ "0868# In~uence of supplemental food on local populations of Peromyscus leucopus[ Journal of Mammalogy\ 59\ 224Ð231[ Hill\ D[A[ "0874# The feeding ecology and survival of phea! sant chicks on arable farmland[ Journal of Applied Ecol! ogy\ 11\ 534Ð543[ Hill\ D[ + Robertson\ P[A[ "0877a# Breeding success of wild and hand!reared ring!necked pheasants[ Journal of Wild! life Management\ 41\ 335Ð349[ Hill\ D[ + Robertson\ P[ "0877b# The Pheasant[ Ecology\ Management and Conservation[ BSP Professional Books\ Oxford[ Hochachka\ W[M[ + Boag\ D[A[ "0876# Food shortage for breeding black!billed magpies "Pica pica#] an experiment using supplemental food[ Canadian Journal of Zoology\ 54\ 0169Ð0163[ Hogstedt\ G[ "0870# E}ect of additional food on reproductive success in the magpie "Pica pica#[ Journal of Animal Ecol! ogy\ 49\ 108Ð118[ Hoodless\ A[N[\ Draycott\ R[A[H[\ Ludiman\ M[N[ + Robertson\ P[A[ "in press# Spring foraging behaviour and diet of released ring!neck pheasants "Phasianus colchicus# in the United Kingdom[ Perdix VII\ International Sym! posium on Partridges\ Quails and Pheasants "eds M[Birkan\ L[M[ Smith\ N[J[ Aebischer\ F[J[ Purroy\ + P[A[ Robert! son#[ Gibier Faune Sauvage\ 04[

Jansson\ C[\ Ekman\ J[ + Bromssen\ A[V[ "0870# Winter mortality and food supply in tits Parus spp[ Oikos\ 26\ 202Ð211[ Jensen\ B[ "0869# E}ect of a fox control programme on the bag of some other game species[ Proceedings of the 8th International Congress of Game Biologists\ p[ 379[ Moscow\ Russia[ Kallander\ H[ "0863# Advancement of laying great tits by the provision of food[ Ibis\ 005\ 254Ð256[ King\ J[R[ "0862# Energetics of reproduction in birds[ Breed! ing Biology of Birds "ed[ D[S[ Farner#\ pp[ 67Ð096[ National Academy of Sciences\ Washington DC[ Lachlan\ C[ + Bray\ R[P[ "0865# Habitat selection by cock pheasants in spring[ Journal of Applied Ecology\ 02\ 580Ð 693[ Leif\ A[P[ "0883# Survival and reproduction of wild and pen!reared ring!necked pheasant hens[ Journal of Wildlife Management\ 47\ 490Ð495[ Man½osa\ S[ "0883# The impact of rotational set!aside on pheasants[ The Game Conservancy Trust Review\ 14\ 72Ð 73[ Martin\ T[E[ "0876# Food as a limit on breeding birds] a life! history perspective[ Annual Review of Ecological Systems\ 07\ 342Ð376[ Monaghan\ P[\ Uttley\ J[D[\ Burns\ M[D[\ Thaine\ C[ + Blackwood\ J[ "0878# The relationship between food supply\ reproductive e}ort and breeding success in Arctic terns Sterna paradisea[ Journal of Animal Ecology\ 47\ 150Ð 163[ Moss\ R[ + Watson\ A[ "0873# Maternal nutrition\ egg qual! ity and breeding success of Scottish ptarmigan Lagopus mutus[ Ibis\ 015\ 101Ð119[ Moss\ R[\ Watson\ A[ + Parr\ R[ "0864# Maternal nutrition and breeding success in red grouse "Lagopus lagopus scot! icus#[ Journal of Animal Ecology\ 33\ 122Ð133[ Newton\ I[ + Marquiss\ M[ "0870# E}ect of additional food on laying dates and clutch size of sparrowhawks Accipiter nisus[ Ornis Scandinavica\ 01\ 113Ð118[ Orians\ G[H[ "0858# On the evolution of mating systems in birds and mammals[ American Naturalist\ 092\ 478Ð592[ Pons\ J[M[ + Migot\ P[ "0884# Life!history strategy of the herring gull] changes in survival and fecundity in a popu! lation subjected to various feeding conditions[ Journal of Animal Ecology\ 53\ 481Ð488[ Rahn\ H[\ Paganelli\ C[V[ + Ar\ A[ "0864# Relation of avian egg weight to body weight[ Auk\ 81\ 649Ð654[ Richner\ H[ "0881# The e}ect of extra food on _tness in breeding carrion crows[ Ecology\ 62\ 229Ð224[ Ridley\ M[W[ + Hill\ D[A[ "0876# Social organization in the pheasant "Phasianus colchicus#] harem formation\ mate selection and the role of mate guarding[ Journal of Zoology\ 100\ 508Ð529[ Robb\ L[A[\ Martin\ K[ + Hannon\ S[J[ "0881# Spring body condition\ fecundity and survival in female willow ptar! migan[ Journal of Animal Ecology\ 50\ 104Ð112[ Robertson\ P[A[ "0874# Habitat selection and the relative distributions of wild and hand!reared pheasants "Pha! sianus colchicus# as determined by winter trapping[ Journal of the World Pheasant Association\ 09\ 76Ð88[ Robertson\ P[A[ "0880# Estimating the nesting success and productivity of British pheasants Phasianus colchicus from nest!record schemes[ Bird Study\ 27\ 62Ð68[ Robertson\ P[A[ "0881# Woodland management for pheasants[ Forestry Commission Bulletin 095\ HMSO\ London[ Robertson\ P[A[ + Dowell\ S[ "0889# The e}ects of hand! rearing on wild gamebird populations[ The Future of Wild Galliformes in the Netherlands "eds J[T[ Lumeij + Y[R[ Hoogeveen#\ pp[ 047Ð60[ Amersfoort\ The Netherlands[ Robertson\ P[A[\ Woodburn\ M[I[A[ + Hill\ D[A[ "0882# Factors a}ecting winter pheasant density in British wood! lands[ Journal of Applied Ecology\ 29\ 348Ð353[

045 Effects of supplementary feeding on pheasants

Þ 0888 British Ecological Society\ Journal of Applied Ecology\ 25\ 036Ð045

Robertson\ P[A[\ Woodburn\ M[I[A[\ Neutel\ W[ + Bealey\ C[E[ "0882# E}ects of land!use on breeding pheasant density[ Journal of Applied Ecology\ 29\ 354Ð366[ Sa_na\ C[\ Burger\ J[\ Gochfeld\ M[ + Wagner\ R[H[ "0877# Evidence for prey limitation of common and roseate tern reproduction[ Condor\ 89\ 741Ð748[ Smith\ J[N[M[\ Montgomerie\ R[D[\ Taitt\ M[J[ + Yom! Tov\ Y[ "0879# A winter feeding experiment on an island song sparrow population[ Oecologia\ 36\ 053Ð069[ Sotherton\ N[W[ "0880# Conservation headlands] a practical combination of intensive cereal farming and conservation[ The Ecology of Temperate Cereal Fields "eds L[G[ Firbank\ N[ Carter\ J[F[ Derbyshire + G[R[ Potts#\ pp[ 262Ð286[ Blackwell Scienti_c Publications\ Oxford[ Sotherton\ N[W[ "0887# Land use changes and the decline of farmland wildlife] an appraisal of the set!aside approach[ Biological Conservation\ 72\ 148Ð157[ Sotherton\ N[W[ + Robertson\ P[A[ "0889# Indirect impacts of pesticides on the production of wild gamebirds in Britain[ Perdix V[ Gray Partridge and Ring!Necked Phea! sant Workshop "eds K[E[ Church\ R[E[ Warner + S[J[ Brady#\ pp[ 73Ð091[ Kansas Department of Wildlife and Parks\ Emporia[ Stoate\ C[ "0885# The changing face of lowland farming and wildlife[ Part 1[ 0834Ð84[ British Wildlife\ 6\ 051Ð061[ Suddaby\ D[ + Ratcli}e\ N[ "0886# The e}ects of ~uctuating food availability on breeding Arctic terns "Sterna par! adisaea#[ Auk\ 003\ 413Ð429[ Tamm\ S[ "0874# Breeding territory quality and agonistic

behavior] e}ects of energy availability and intruder pres! sure in hummingbirds[ Behavioural Ecology and Sociobi! ology\ 05\ 192Ð196[ Trautman\ C[G[\ Frederickson\ L[F[ + Carter\ A[V[ "0863# Relationship of red foxes and other predators to popu! lations of ring!necked pheasants and other prey\ South Dakota[ Transactions of the North American Wildlife Con! ference\ 28\ 130Ð144[ Van Balen\ J[H[ "0879# Population ~uctuations of the great tit and feeding conditions in winter[ Ardea\ 57\ 032Ð053[ Watson\ A[\ Moss\ R[ + Parr\ R[ "0873# E}ects of food enrichment on numbers and spacing behaviour of red grouse[ Journal of Animal Ecology\ 42\ 552Ð567[ Watson\ A[ + O|Hare\ P[J[ "0868# Red grouse populations on experimentally treated and untreated Irish bog[ Journal of Applied Ecology\ 05\ 322Ð341[ Wilkinson\ L[ "0889# SYSTAT\ the System for Statistics[ Sys! tat Inc[\ Evanstan\ Illinois\ USA[ Wise\ D[R[ "0883# Weight\ carcase composition and repro! ductive performance of pheasants "Phasianus colchicus# fed restricted or unrestricted diets[ Research in Veterinary Science\ 46\ 008Ð013[ Yom!Tov\ Y[ "0863# The e}ect of food and predation on breeding density and success\ clutch size and laying date of the crow "Corvus corone L[ #[ Journal of Animal Ecology\ 32\ 368Ð387[

Received 17 March 0887^ revision received 10 December 0887