Social Attraction and the Feeding Behaviour of Domestic Hens

Beha.lou,., Proo.OSSi1s, 18 (1989) 71-85 Elsevier

71

SOCIAL lIl'TRACTlON AMl THE FEEDING BWAVIOUR OF IlO!IESTlC HENS

Andrew D. MUls and Jean"Mic:heJ

~6ure

Station de Rech~rches Avkloles, Centre I.N.R.A. de Tours-Nouzilly, 37380 Monnale, Franoe

( Aocepte4 17 N'ovellber 1989 )

ABSTRACT

MUls, A.D. and Faure, J.M., 1989." Social attraction and the feeding behaviour of domesUc hens9 Behav. ProcefiS. 71-85 TradltbnBl models of tbe feeding behaviour of · doml'stic hens (GalluB gallL1s domoGUaur;) predict tnat dOminant birds wUl attempt to mo"nopollse iOCi'S'i to !oed resources and wifl be intolertont of su.bordin.8te birds ieadlng lrr their .

pro)timl1y. Furthermore, '/nlln food Is avauable at a number of different {&paUally S9paratetl sites}, birds should disperse when feed1nq. The results 9f the pres"ent .study indicated that, at leBst in small grollps of birdli, . these predJcUons do not hold true. "'hen bens. kept in pens in groupe 01 thio"O, .,.'ere offered the possibility cf feeding under vario:us degrees of physlc-_.\ and/or visual isolation from ono another, (l.e. at a circular feeder quadratically partitioned with wood, Olass or nominal divisions), they chose to feed · in proximity to one another (i.e. in the same or adjacent quadrants ot the feeder) significantly more than expected by chance, irr~spective of the degree of physical isolation bfttwoon feeding altes. In a second exporiment. 0"0 birds at t! IJroup of three was prevented from fesding with her two pen mates and could onl1f fead at a site distal trom thorn. Under auch conditions the ·isolated'! bird spent significantly losn time feeding than when it was able to feed with tho othar two birds end presented behaviour (signlUcanUy increased levels of locomotor aotlvity and preeninQ) possibly symptomatic of frustration. It is sUCJgested that feeding birds are str.;mqly attracted to one another and that, at lea&t in ,the strains and Qroup sUes conSidered, soc1a.l attraction Bnd available feeding space are Important influences on the manner 1" which tJenJ.; space themselves when feedinG.

Key words ! dom9sUc hlms ... ~Uus gallus domesticus .. feedinr;;: bet.av!'.lU1 soci8l attra9tiDn - digplacem&nt preening .. frustration

0376·63S7/S9/$03.S0 © 1989 E1...itr Sclen::o Publishers B.v. (lliomedi<:al Division)

72

INTRODUCTION

VarJous studies of free llv1ng avian speciM (for references see ; Coss-Custard, 1970 : Davi'ls, 1978 ; Krebs and Davlos, 1981 ; Wittenberqor, 1981 ; Elgar, 1986) have shown that the spacino behaviour of feedlnQ birds reUec15

a conflict between factors which tend to draw tndiYtclu&ls toqether and

factors which tend, to cause them to separate. However I traditional models of the Gootal behaviour' ·01 domes tic hens (e.g. Sehjelder\.lppe--Ebbe, 1922. 1935 ; WoodGush. ~9S5, 1911 ; Me Bride . 1964. 1970) tond to emphasise those factors which cause birds to separate (aggression, axnpeUUon and the maintenance of an exclusive personal space ; see Me BrJde, 1964. 1970) and to tonore the possibUity that teodinq birds wUl be attraotod to one anothor. One rosult 01 this Is that thero Is now B general, if uncrit1cal, tendency to think of much of the social behavtOur oC domestic chickens in terms of a hierarchial group within which all aspects of Ell bJrols behaviour can be reloled to its social status or rank (S yme, 1974 i Rushen, 19a3 j Faure, 1995)4 Suchlike models of the behaviour of domestic hen$ predict that dominant birds will have priority of access to resources and will bt3 Intolerant of 5llbord.1nate birds fMdlng In thetr proKlmlty (see WOOd-Gush, 1971 ; HU(Jhes and BlaCk. 1975; Banks U., 1979). However. as Banks!!...!!. (1979) have pointed out, ~~e~1t h~"e been (ew syslemoUc: studies designed to test theca prodictions (sec also fevicws by Syrno. 1974 ; Rushon, 1983 ; Meunier-Salaun. 1993). Furtherroure. several recent studies appear to contradIct theso predictions. FJrst . Banks !t...!!. (l919j hav0 reported that. at least 1n sm6l.l groups of laying hens. "although there is a relationship between soclal rank and the frequency and duration 01 feed in g behaviour, measures or rank /lre rarely congruent to mea~ures of feeding. Second, Faure and Lagadlc (1986 ) have shown. by means of operant conditioning techniques, that groups of hens am rarely prepared to 1',lork (key peckJ for an area of feeding opace oreater than the minbnum requJred to ellOY.' eU bkds 1n the group simultaneous ac~ss to the feeder. Third. Meunler-Salaun end Faure (1984) and Huon.!t.!!. (1986) have" demonstrated thal hens kept in :omall grou;:as show en activo proferenco " for feeding "together and show little aggrossion whon dOing GO. This paper presents th@ results of two experiments desiQned to investigates to whal extent the feedlnq bcha"/iou:- ?f domestic hans is influenced by soda! attr.3ction (i.e. tl1e tendency 01 birds to feed together) as opposed to aggress:lon and competition. In the first exper!:ool'lt the preferences: of birds tor feeding Unciei" various degrees o[ physical and visual isolflUon wore studied. In the second expertmc::nt the consequences of donytn9 birds the opportunity to feed 1n close pro)t!mity to One "another were investigated.

73 MATERIALS AND METHODS Experiment 1. PreJonmces lor varlou. d e _ 01 physical and .leual ~tIon

whon leodlnQ

J.'llIiIaIs .nd husbandry A total of la ISA-Brown laying hens were usod. The animals ' wero obtained as day old chicks from a commerdal supplier. From day old to 18 weeks of age the birds wore housed in a floor pen. 'At 18 wooks ot ago lho" birds were randomly .a.sslgned to aix grolJps Qf thieo birds per group. Each group was then hou's ed in 8 floor pon where It remalnod throu.ghout the experiment. Each ' POQ measured 2 m x1. 2 m (longth x width). Tho watls o( tho pens woro saUd plywood tr. a height of 1 m with wJre meah above. ·The floors of the pent; wore covered wllh wood-shavings. All the pons ' were located in the same poultry house. The ,lllJhtinO' reolmen in the poultry hOllsO was artiUcsUy reguJeted at IS h of ltO"hl to 9 h of darknosD. Temperature and humidity in "the poultry house were / not amtroUod and followed climatic vanaUans. Weter was avallable ad llbitum at aU t1mes . ---Food \VQ$ available ad llbltum except dur'ln~ tho stud)' porbd (see below). Each pen was furn1s~ sinole clrculer cone feoder whieh was suspended, at a helqht of 4 em above the floor, from the centre of the roof of tno pon t E'ach -of these feeders was S4 cm high, had a basal diameter of 110 cm Bnd offered a tOtal feeding area of 491 cmZ. '

ExperJmont81

foeder&

The experimental feeders WOre the blra1l 1 usucd feedors quedraticolly partitioned with .Ither 40 em (blOh) x 19.5 em (10M) plywood divisions (visual · and physical isolation 01 quad
procedures

AD tests were carried out when the birds were 30-4.0 weeks of age. During t.he 9 d boloro testino each group of birds was: dcprtv.od 6f food for 6 h on each day. At the end 01 the 6 h deprivatfon period each group of birds wae presented with food contained in ono of three types of partitioned fcedcr and allowed to fcod for 20 min. At the , (lnd of this 20 min feeding porlod the feedor pactions were replaced with those to be usod the followlnu ' day an<1 the feeder left In place untn its removal the following: day. Dudnt;,··-this 9 d period each

group of birds was presented with eoch type of feedor ~h ree times. However, within groups the order In which the fcedors wore presentec.Pwas random. This 9 d J)re .. tesUng period was carried out In orrier to habituate the birris to the experimental feeders and to the six hour perbd of food depriva!.!on. On test days the birds were aqain deprived of food for 5 h and, then , presented with food in one of the three par titioned feaders . DurJrl\t the 20 min after presentation of the food the positions of the birds at the ,l0:i-:Jer (if they were present, were noted every 10 s. This 10 s scan Interval wJe,' chosen a~d the lndependence of scans aBsumed for the following reasons: Flrstl'y, MeunicrSaI.lOn and Faure (1984) have shown that, under broadly simOnr Qxpodmental conditions , birds, of tho same gonetic stock to those used in the present study. change feeding posltton every 13 - 18 seconds. Secondly. a preliminary analysts of the data revealed that the proportion of paired successive scans which were

74 Identbl wes only 27%. Nino typOt; of feedlng positions were possible. · These were : 0 = no birds feeding ; 1 =: only one bird feeding ; 2NA • two birds f~dtn9

in non-adjacent quadrants of the feeder ; 2A

a:

two birds (eedlng in

adjacent quadrants; 2S = two birds feeding in the same quadrant; 2S ... INA tYlO

bJrds feod1nO In the same quadrant nnd 1 bird feedlno in a

quadrant; 2S + lA

~

0

non~dJacent

two birds feeding In the same qU8drant and 1 btrds feecUno

in an adjacent quadrant ; 3A .. three birds feedinQl In adjacent quadrants ; and 3S • three birds feeding in the same quadrant . AU observations were made using 8 CZlmOra which was suspended aboye the · feeder. The imago capturod by t he camera was monitorod on 8 televlslon located In an ante-roo:n adjacent to the pens. Observations wen made dlrectly from tho

television using a "Datemyte" 1000 data collector (Electro General Corporation, MtnneGota, U.S.A.). To facU j1,jle Id ~ nUUC81tlon, on the black and white television, each bird was indlvl,; uaUy merkod by meG"; of a cloth badqe strapped across tts back. At the end of the observation -the feeder partitions were removed and replaced With the partttt\" ns to be- used the following day. If the bleds were not to be observed the following day the existing di'liaions WtrG left In place. Experlment 1. BebavlDura! conaequences 01 den)'\JIg bIrds "tho opportunity to feed In clDoe proximity to ODe another " Animals

and

husbandry

Animals and husbandry conditions were as described In experiment 1 with the (ollowing exceptions. First, at the lime of the experiment the animals wero between 50 and 62 weeks of age. Second, food was available from rectanQWar food trouQhs located at elther end of the pen . Each of these feeders, which mQasurud 50 em x 5 em (lenoth x wIdth) was attachGd to the front of a wire mesh CGQe. Each of these cages measured 60 cm x 30 em x 40 em (lenoth x depth x height) . The front of each caQe wos designed tn a nUu\ner such tht the (eeder was accessible from both the ex.terlor and the tnlorloa: of the Celge (see Figure 1). Ex:perimental

procedures

During the 6 days before testing the followinO tnlning procedure was carried out. Each day. two 01 the blrds from each Group were placed in one of the two cages located at elther end of thetr pen. The tltlx-d bled WillS 10ft free in the pen. The birds Viera then deprived of lood for 6 hr . After the 6 hr of tood - deprivation ahe (ood trouohs Were replaced ond tho birds allowed to feed (or 30 min. After the 30 min fee ding period the two birds in the mOe were released into the pen. 1'he feeders were left in place until their removal the foUowtno day. During the six dElYs of training each bird spen t four ~erJods of food deprtvatlon in one of the two cages (i .e. twice with each of its two pon mates) and two periods free in the pOn. On test days the procedure was as described above. HOIf,'Cver, In the experimental tests, the third bled (I.e. the bird not conftoed In one of the cages) was prevented from feeding with tho other two -bledt by means of a wire mesh screen placed tn front of the feeder In front of their cage end could only feed at the feeder In front of the empty cage . In the control tests t he third bird was free to feed with the other two blrds or at the feeder in front o( the empty -cage. DurinQ the 30 min atter presentatJon of the food , the behavtol1r ot the third (sQe Pigure l} bJrd was ob~erved and the followinO parameters noted : 1) The number of times the bird crossed from one half of the pen_ to the other (called tran sitions ). 2) The number of steps the bird took. 3) The number of times the bird preened itself (preens were donned as described by Dunc~(l and

Wood-Gush. 1972). 4) The tlme{s) spent In the half of the pon with the cage

containing the other two birds. 5) The time (s) s pent in the hlf of the pen

75 containing the empty 04g0. 6). 'rho lime (0) aponl fo.dlng al ..ch of tho two feeders (or in the exrerlmental test the tbne spent feaclino at . the feeder In fr~nl of the empty cage and tbe Ume spent in close pro;.:lmtty to the 1nace~Jble feeder in front of the caoe cont4J.n1nq the other moo t.'k~~\: ). 1) The total tlmo spent feeding .. Each bird was tested .1W\ce In the conlrol te.t and twlco In Iho exporlmental test. Batwoen tests wlthln birds the pO$lUons 01 the empty C40e and the eege containing the other ~"O birds were reversed In orda! to avoJd -end effects " in the pens. No oroup was tested more than once on anv day.

Figure 1. Plan (not to scale) 01 the Jlen set ups used in experJment 2.

Wire mesh "trean leSI cnlr)

(~xp.tlm.nl8l

Hypothetical mld·llne Two bJrds, from an estabUshed group of 3 pen mates, were pJaced. in one of the two holdino cages located at either en~ of the pen ; the remaining bled was left f ree in the pon. The front of lha holdlnQ' cages w~re des1Q' ned such that the feeders wl3re accessible to the birds in a cage and to the bird free in the pon. After the birds had been deprived of food for six hours. food was plaC~d in each o[ the tHO feeders and the behaviour of the bird left free in the pen rllonitored. In the control tests the ' 'free bird' could feed at . the fe~der infront of the Ofloe contalnlnQ t he other two birds and 8t the feeder infront ' oj the empty cage. In the e)(per~menta1 telJts the free bird was prevented from feeding with the other two birds by means of . a ,dre mesh screen ptaced 1n front of the ttedor infront 01 their C&Qo and could only feed a t the feeder in1ront 01 the eml)ty C&go. tor further det..\ils (lJ procedures and of the behavioural meas ure& made see the text.

Statistical

analysis

oj

result 8

Non-)Jerametric statistics were .used io all enalyses. In oxperiment 1 !:\tr·o dUferent analyses were Olrried. out. In thn f1rst~ tor each obsl9:vatlon of eacb group of thne birds at each of the three types of feeder, the number Of . times a partf.cu.Jar teeding position was recorded was expressed as Q proportion of tM total nUlnb-::r of scans made durln9 that obGurvatJon . ComparJsot.:.I of the

76

proportional incidences of tho VIlTlous feeding positlons adoptod by the oroups of three birds were made using Mann ..Whitney nun tests (Stegel, 1956). The second analysis considered only those occastons whon two or three birds , respectlvely were prosent at tbe ' feeder. For each observation of each 9roup ot birds, at oach type of feeder, the sum of the number of times that two or thrce birds respectively were presont at the feeder was calculated. The sum obtained was then used to calculate the incidences of the various feeding postUons that

would have been ex pected if the bJrds had been spacing thNn30}ves at ra.ndom., The

mean observed ond expected values of the incidences of ollch typo of feeding position at each type of feeder were then calculated and expressed as observed

~~p:~~~cteyda1Ure~tfO~'ere'rh~al:~~tl!~ca~~~n:f x1~::~~~1~~ ~~~de::aS o~er;l:d t:~: (Parkor. 1973). In experiment 2, paired comparisons of the incidences or dUrations of the various parameters moasured tn the control find experimental tests VJere made using two taUed Mann"WhUney IIU" tests (Si~gel, 1956).

RESULTS

Experimont .1. Preferences for various degrees of phyeicel and vieue1 when feeding

lsolaUo.

Fioure 2 shows the absolute proportional tncidenoes of tho various teedino positions adopted by the members of the oroups of three hens when presented with food contained in circolar feeders quadrllUcaUy partitioned with. em high wood, 40 om high glass or 3 ern hloh wood di\,1sions. With the data presented in such terms, typo of feoder division had littl~ influence on the wa~' in which birds spaced tttemseives whon feedtno. Significant differences between types of feeder division e:dsted only on those occasions when only one bird was j:lresent at the feeder and when, if only two bird£; were present at the feeder, those two. birds wero feeding in adjilcent quadrants of the feeder. The number of ·occasions when only one bird was present at the leeder was siQniUoantly lower when the feeder was . partitioned with 3 em h1Qh wood diVisions than when it l.IIas partitioned with 4.0 cm hiOh woed divisions or 40 em high glasl;> divisions. There were no signiUcant dUferences botween 40 em high wood and 40 em high glass dhrislons. The number of occasions when only two birds wore prosent at the feeder, and. feeding tn adjacent quadrants of the feAder. was signiUcantly highor when the feeder was partitioned with 40 cm hiOh Q~a5s divisions than whon it was parUtfoned with 40 em hlQh wood or 3 em high WOod diylslons. When two or three birds were present at the feeder I the way in which t he birds spaced themselves followed a Qoncrally consistent · pattern &t aU thr~ types of fceder (Figure 2). Of those occasions when two birds wore present 3t the foador the incidence of condltion 2NA was signtftcantly lower than the

-to

incidence.$; or conditions 2A and 2S whlltcvor the type of feeder divtsion. When

77 Fioure 2. Mean (+ SEM) proportional 'ncidences of various tYPDB of feedino

positions adopted by groups of three hens when presented with food conta1ned in ctrcular leeders quadratically portltloned with 40 em' high wood (s triped bors'. 40 em high glass (plain bars) or 3 em high wood divisions (checked bars) •

•2

•

•1

"z 9

." <

u 0

z

0

. ~

=

if

2.

2HA

2.

C~ND'TION

.+.

••

.4

0 0

FEEDING

NO. OF BIRDS

U

...

0

,3

S

W

.,,;z < ~ ~

.2 .1

MO, Of

2S+ 1HA

BIRDS

29+ 'A

FEEDING

3A

39

CONDITION

For an Ilxplanatlon of terms see text. For a qiv~n numbGf of birds feedinq in a oiven feedinq position '(i.e. within cllch block of three bars) birs bearing dUferent letters differ siOnUicanUy at P < 0.05 ,(two taUed Mllnn-Whltney

tests). For a given number of birds

{~aging

l Ull

and for a oiven type o{ feeder

division but irrespeotive of feeding condition bars bearing diCferent symbo;)ls differ ston1f1cantly at pc 0.05 (two !aUed Mann ...Wh1tney

IIUR

tests).

78 the feeders were partitioned with 40

high wood or 3 em high wood ,divisions incidences of conditions 2A and 2S. However, when tho feeder was partit1onf,1 with glass divisions the incidence of Cn ~

there were no s10nUIcant differences in

~he

condition 2A was s19nificantly higher than that of condition

~S.

On those

occasions when three birds were present at the feeder the incidences of conditions 25 + lNA and 3S did not significantly betWG9n feeders. mmfiarly, the

incidences of conditions 2S + lNA and 3A were not siqniflcanUv dUfl'rent at any of the feeders. When the feeders were partitioned with 4.0 em hlOh glass or 3 em hioh wood divisions the incidences of conditions 2S ,~ lNA and 3S were significantly lower than those of 28 + lA and 3A. However, when tho feeder was partitioned with 40 em hiOh wood divisions the incidence of condition 25 + INA was significantly Jower than those of conditions 2S + lA and 3A but the l~cidence of condiUon 3S, although slgniUcantly lower than that ot condition 28 + LA, did not dUfer 61gn1f1canUy from that of :ondlUon 3A.

Figure 3 shows the ratios of the obst>rt/ed incidences "of the various feeding positions adopted by two or three birds respectivoly to those expected if the birds were spacing themselves at random (i.e. independanUy from one another). On tbose occasions when two birds were present at the fceder condition 2NA occurred significantly less than expected by chance .at aU typos of feeder. Condition 2A occurred at levels approximately equal':) thOl'i8 expected by chance when the feeders where partitioned with 40 em high or 3 em high wood divisions but significantly more than expected by chance when they were partitioned with glass divisions. Condition 28 occurred si91D1f1canUy more than expected by chance when the feeders were partitioned" with 40 em or 3 em hiQh wO'.Jd divir;1ons but not when the!'" were partitioned with olass

divl~ions.

On those occasions when

three birds wer" )l":"esent at the feeder condition 2i .. INA occurred sfgnlUcantly less than expected by chance and condiUlJn 3A It", wels -approximately equal to chance at all types of feeder. Condition 3S "Ot " ~.rred "more frequently than expected by chance when the feeders were partitioned wIth 40 em or 3 em high wood divisions but only at. levels approximately equal to chunce whell they were partitioned with glass divisions. Experiment 2.

Behavioural consequences of denying birds the

opportunity to feed in

clos~ proximity

to one another

Table 1 shows the mean (!. SEM) incidences or durations ot the various parameters measured tn the control and experimental tests. AU parameters

79 differed

aSqntfica.nUy

belwe9n

tne

cuntrol and

experimental

teets • . .81rde

prevented from feedinq with the1r pen mates showed &igniricant increases :In the number of stops tak.en. number of preens and num.ber transitions from one half

the pen to the other, and

8

~f

signlUcont dec!'t':lw in totel time spent feeding.

Figure 3. RQtio of observed to expaoted incidences of tho feedinQ positions adopted by oroups of three hens when presented with food conte.ined in circular feeders quad.ratically partitioned with 40 em hlqh wood (striped bars), 40 em high glass (plain bal") or 3 COl hlgh wood divisions (chec!
o

w

ICol

...>
.

w

.: Z:.

o

I-

">w

···············1

.. o

II!

W

In

o

~

II!

2NA

3 3 2 NO. OF BIRDS FEEDING 2A 2S 25. 2S.

INA

1A

3 3A

3S

CONDITION

fDr an explanation of terms see text. Bars bearing asterlsks diUer ly from chanco (II' fl peO.OS; 11* = P~~O.Ol j *'*~ .. P< 0.001).

~iQn;U'jcant­

80

Table 1. Behavlourol consequenc(Js of denying birds the opportunity to feed together aftor six houre of food doprivation

Control

Experimental

Time tn half of pen with

1271.47 (!. B6.08)

502.97 (t 54.21)

Timo in half of pen away

529.53 (t 83.31)

1297.17 (t 54 . 24)

Total feeding time (8)

1561.56 (t 3B.95)

1145. 19 (t 55.50)

Time feeding with others (6)

1104.61 (t BO.02)

334031 (! 40.19)

456.94 (! 79.70)

1145.19 (! 55.50)

othor 2 bird. (.) from othor 2

bl1'~s

Time feeding alono Transitions

(s)

(0)

7.09 (! 1. 14)

18. 31 (! 2.37)

Stop, (n)

217.25 (! 18.53)

553.81 (! 43.62)

Preens (n)

1.94 (! 0. 25)

6. 83 (! 1.04)

(n)

... P

For an ex plonation of behaviour patternc sao text. n = numbor ; s = seconds.

Values are moans (,!SEM). ***. pcO.OOl.

DISCUSSION

Expcr1ment 1. Preforencos for various degrees of physical and vJsual isolation

when

feedlng

Although thero wl!re some discrepancies betv.:een the absolute and probabl1stic incldonces of the various (sociino positions (see below) thore was a

9cneral tendoncy for birds to avoid feoding In non"'edjacent quadrants of the feedor. to feed in adjacent quadrants of the 'fceder on a number of occasions approximately equal to that expected by chance and to (ced in tho sarno quadrant of tho feeder significantly more than expected by chance. This tendoncy is in broad agreement with Meunler ...SalaOn and Faure's (1984) f!ndlno that. when food is avaUable at a number of spatially separated sUo::;, tho probability that birds will feed toqethor increasos with the distance batween feeding sitos. The major ~xccptions to this tend.ency were the loVi absolute incidonces of condHion 3S at all typeD of Jeeder and the high llbsolute lJnd probolisUc incidencos of condition 2A when the feeder was partlUonP.d with olass divislons. The low

81 absolute lncldenc8(; of condition 3S (it should bo romembered here that even

these relatively low ineldeRcn were slgntucanUy groater than expected by chance whon the feoder was partitionod with 40 em or 3 em hlOh wood dlvtalone)

might have be()n due to the limited feedino space available withJn one quadrant oC tho Ceed.r (27 em • 9 em por bird 11 throe birds Ced slmultllneou.ly In the same quadrant 1)( the feeder). This hypotbesis 1s sup"orted by Hughes and , Black

(1976, 1977) and Hu;h.s (1983) who blSO .u;;•• t that the amount oC 'paee

avaUoble to accommodate the birds bodies 10 a limiting fector whon sevoral birds try tn feod together I and by the high incidencGs of condition 2S + lA, which tmpUes thet if 8 bird was physically unable to feed in a quadrant already occupied by the other two birds it would ten~ to move Into en adjacent quadr&nt. The high incidence of condition 2A when the feeder was partitioned with glees dtvlsions 1s less easily explained and is conslderod bolow.

With the exceptions monUoned sbovo, ty pe of foeder divisiOn (and thus the degree of isol&Uon between quadrants) had mUe etrElct on the way fn whioh

the birds spaced themselves when fceding. Thus, it would appear that the factora thllt attrc.cted the birds to one another acted during the appetitive stages of

feoding bohaviour (t.e. when the birds were approeching or moving around the I.edor) rather thon durln9 Ceedln; It••U. The Cact thst condition 2A ooourrod stonit1ce.ntl~·

more than expected by chance when the feeder was partitioned with

glass divisions. mtoht be construed as evidence that visual contact when ~oedinO' also influences the birdIe apaglng behaviour. Some ovidenco in support ,. of this last statement is provided by the faot thet condltlons 2S and 3S occl.lrred only at levels approximately equal ,to ohanco whon the food(lrs woro partitionod with glass divisions but at level, significantly greater than those expected by chance when they wftre po.rt~ttonftd with 40 cm or J em high wood divisions. However, Guch an intepretatton also requires that tho 3 em hiOh wood dl'1ifJions provIded e de,.;:r"e of isoh.Hon between quadrants equal to that proV'ided by the 40 em hlljJh wood divisions a.nd must therefore be regarded as speCUlative. Experiment 2. Bohavlourol consequonces of denying bkds the opportunity to feed in close prox1m1ty to one another Increases 1n the incidencos of preenino and of locomotor activ1ty (at least in the form of stereotyped backward and forward pacing bohav1our) are widely considered be indicative of frustration in tho domestic fowl ' (Duncan,

"to

1970 i Duncan and \Yood-Gush, 1912 ; Mllls and

Wood~ush,

1985). This, tOQ9lher

82 with the decreasud time spent feeding ill the e;~parimental situation, impUes that birds have 8 strong tendency to feed in close proximity to one another and that the thwarting of this tendency may. lead to frustration and tho disruption of normal feeding behavlour4 The strength 01 this tendency for birds to feed together" is emphasised by the !act that In _the experimental test, b1rdfl spent . signtticanUy leas ttme feedino then In the conlrol test. However, 10 the context it 1s pertinent to point out that reduced f~dlnCJ time shown by birds .1n the experimental test may not represent a redu\)tion :in food consumption. Barbato !!.!!!. (1980) have shown that birds may indulge in "non-consumatoryU or "playll feeding aotivities and Huon~. (1986) have demonstrated that birds f\leding communally show more play feeding and lower feeding rates than birds feeding 1n isolation. GENERAL DISCUSSION The results of the experiments described in this p9per imply that models of the social spacing behaviour of domestic hens which are based on dominance, compatit!on and the maintenBnoe of an exclusive personal sp(l.ce dQ n()t adequately describe the behaviour of feeding hens. In experiment 1 there was no evtdence that birds souqht isolation from one another when feeding Or that thay attempted to prevent other birds from feeding in their proximity. Convers~y. there was evidence t hat birds tended to feed in proximity to one o.nother significantly more them would be expected by chance. Relatedly, in expe1'1ment 2,

preventing birds from feeding tOgether led to a decrease in time spent at the feeder and increafjes in behaviour, possibly indicative of frustration. 'l'bus~ it would appear that thG spacing behaviour of feedinq hens, as is th9 cas:e in other avian species, is CJoverned as muoh by tacton~ which tend. to draw birds together as by factors' which tend to drive them apart. Several independent studies lend indirect support to this stat~ment. Doyen and Zayan (l984) observed th6.t PUSh:lliQ and shoving were common intoractions betwe£on pairs of feedlno birds and concluded \hnt, since pushing never resulted in the exclusion of one or other of

tht3 birds f.rom the feeder. such behaviour was hO),S much connocted with sociability or iliHllation as it wa~ with social 1ntoler6.. .'\ce imposed bV space incompaUbilltl" and Meunier"SeleOn 4nd Faure (1984) and H~i:~ !.L!!. (1986) have shown thOlt, U groups of hens ere presented with food. at a r.~mber of spatially separated sites, the tend~ncy for savora} birds to feed togethe r lnef"&~ses with inter-sHe feeding dlst,nce wh11st levels of alJlJression r.e~ain constant (LUl

83 (1968) reports a similar ab!;onCG of 8 relationship· between aggression and inter feeding site distance). However, It should not be assumed th~t the epacino ~h8\,jour of dQhlesti<':

hens

can

b&

completely

explained

"social affllfation" or 'soclal auraction"

in

terms

~Mms. 4l~jd

of

Fa-ure,

"J:iocielbWty· 1986~.

or

Although

evidence- eXists thal the fendinljJ behavioLJr of ona dOITtesUc hen is ,an attrac~tve '

stiml!luB for 3notheor dome'>Ut! hert 'Keellng and DunC!ln, 19918), the present st~dy enO'."ed tltat, althouqh anlmt.ols mlSY show an overaU . tendency to feed 'tog&tnar, ' thi:.. tendency Is r.ot absoluM and is subject to consideroble e,n'!lronmental and individual variat:Jon. Furthermore, It may well be tniprudenl to QGneraltse principles of social spacing in lreo living -avian species (soe Davies, 1978 ; Krebs 6nd Davis, 1981) to domO.:.lUC ohlckens (KeelinQ and Duncan, 1908). Domestio chickens have baen subject to toletlUon tn and now usually live 1n controlled environments where there 1s nQ risk of predation and fOod is Gvailable !!.. ~. Thus~ much of the cost··benefit analysis used in spOicing models' of free living speciel! mey be iMppropr.iate to the domestic chicken. Howaver, tn10 dees not tMan that the spacino behavIour of domestic cbickens is not complex. The complexiW of tne spacing behaviour of feeding domeosUc chickens Is lIt'1derUQsd by the iol1owinO oDsarv nttons. Dorn1nanoe gives priority of access to food resources (Wood .. Gush, 1911 ; t'eure"1977 ; Banks !!....&., 1979; MeunIor" Salailn and FSLlrlD, 19114) but social rOink is ral'e1y rougrtJent with measurl1G of feeding (Eanks ~., 1919) and b1r,'is form feed-iog- asaoc1etfcms w,hich cear no ralatLonshlp to lheit' Boehl rank (FaI.Jro, 1917). In addlUon, giving groups of hens nccess to an area of feedlno BpOCO adeqUllte to ac::ommodate the simultaneous p~'esence of all birds at the feeder nsult; in i' pattern of feedinG behavtour wtlich has a semblance of the diurnal rhythms of feedina behe.vtour described by Savory (1978) ~ but does not necossarUy lead to all b1rds in a group feedinG III the same time (Hughes, 1983 ; Hughes a~r;t Block, 1916, 1977). In oonc1uslon, the spacing m 'havtour of feeding hens cannot bo E.lxpladned solely .tn terms of dominant-it, l'Ompetit1rm a~d the maintena.nce of an e:roluslv6 r.:ersonal space, rlor ca.n it be O).~platned solely In terms of BOCIa~Utly or f!vc:lal attraction. It would seem more likely that spacino behaviour of this spE:cles, like lhat of mtloy other species. depends on, what are at present illdafin9d, Interactions between Ihose factors.

S4 REFERENCES Banks, B.M., Wood ..Oush, D.G.M., HUQhes, 8.0. and Mank.ovich, N.]. (1979).900101 rank and priority of 81.."Cass to resources 1n th'~ dor.~estic fowl. Behavo

Processes, 4 : 197.. 209. Barboto, GfF., Cherry, J.A'f Siegel, P.B. and Van Krey, H.P. (leBO). QuanUtative analysis of the feeding behaviour of four popuiatioruJ. of chickens.

Physicl. Be-hav., !i : 885-691. Davies, N,B. (1978). Ecological questions.
1.,.tI.

a

HUDrl. F.,-MrJunier-SalaCJl1., M.e • .and Faure, J.M. (1986). Pell'der dEOiSiQIl an(] avalla.ble feeding spare infhtente the leeding behaviour of ben:::;~ Ap[.ll. Anhn..

!lehov. Sci •• 1$ : 65-70. Keeling, L.J . and Duncan, i~J.H. (1988). The eHect of activity transitions on spacing behaviour in domestic fowl. In : Unshelm. 1" Van Putten. G •• Zeeb; K., and Esicebo, I. (Editors), Proceedings of at the International conljJress On Applied Ethology in Farm-Animals ; Swedish University of Agricultural Science~, ~kara, Sweden. pp. 291·296. Krebs, J.n. and Davies, N.B. (1981). An illtroducUon to behavioural e~lc g7' Btft:kwell Scientific Publications: i Oxford, Londoll, J::dinburoh, Bostc:;.;l, Mel bourne. 292 pp. Lm, A. (19581. Spatial orlJatl!saUon in small flocks of domestic fowl. Eehav., 31 : 2SS-290. McSrIae, G. U96t!j. So 11 discrim.1natLon and 511b-flock formation in the dome$t!-; fowl. Anim. Behavo, 12 ; 264-267. McBride, G. (1970). The social o:;!rtrol of behaviour in fowls. In : S.M. Freeman and R.F. Gordon (Editors" Aspeots of poultry behaviour. Brit. Poultry Sci., pp. 3-13 ~

os McBrj,de, G., JamlJ$, J.W. and Shoffner, R.N. (1S63). Social forces d&termin:lng spaclnQ and head orientation in a flock of domestic hens. Nature (Lond.), 197 ; 1272-1273. Meuruer-Salaan, M.C. (1983). Relations Inter-lndlvldueU•• dans de. petits o:r~upes d~ pouls:: dorneattques. Effet des conditions d l 61ev8Qo. Unpubl1s.,bed These de 30m,e Cycle, Unlvo de Rennes It 144 pp. Meunier-Salaan, M.C. and Faure, J .M. (1984/198.), On the I•• dino and social neh.vbur of the layino hen. Appl. Anim. Bohav. Sci., 13 ; 129-141. MWs, A.D. Bnd WoodooGlI;Sh, D.G.M. (1985). Pre--laylnQ behaVIOur tn haltery caqes. Brll. Poultry Sci •• 26 ; 247-252. Mnls, A.D. and Fc.ure .. j.:M. (1986). Socid attraction as e factor in the feedillCJ bema.,iour of domeatic hens. in : M. Li5rb1er (Editor)., PraceecUngs of the 7th EurOpruiR Po;.!ltry Conference, Vol. 2, pp. 1093... 11391. . Par1:.er, R.E. (l&73). Intr