(Received 11th June 1974)

Transcription

1 INDUCTION OF INCUBATION BEHAVIOUR IN MALE RING DOVES (STREPTOPELIA RISORIA): A BEHAVIOURAL ANALYSIS MEI-FANG CHENG Institute f Animal Behavir, Rutgers State University, 101 Warren Street, Newark, New Jersey 07102, U.S.A. (Received 11th June 1974) Summary. Male ring dves (Streplpelia risria) were treated with either prgesterne r dexamethasne (a pwerful ACTH inhibitr) and tested fr incubatin behaviur. Prgesterne treatments shrtened the latency f incubatin respnse by facilitating nest-related pre-incubatin behaviur patterns in the nest bwl and cmpnents f incubatin behaviur. The accumulated rather than the daily dse level f prgesterne injectins appeared t be the determinant factr in mediating behaviural effects. Dexamethasne treatment at the dsage f 100 \g=m\g/day fr 7 days inhibited the verall expressin f male curtship behaviur. Nne f the dexamethasne-treated ring dves `sat' in 2 weeks. It is suggested that the hrmnal and situatinal (nn-hrmnal) cues are nt nly imprtant cntributry factrs but als cmplement ne anther in the inductin f incubatin behaviur. INTRODUCTION 1961), Lehrman As a result f his experimental findings (Lehrman, 1958, pstulated that prgesterne secretin which was believed t surge arund the time f vulatin was the hrmnal basis fr the inductin f incubatin behaviur in male and female ring dves (Streptpelia risria). This pstulate was supplemented and cnfirmed in later studies in which the synergistic effect f andrgen r estrgen plus prgesterne, but nt f the gnadal hrmnes alne, was fund t induce a shrter latency f incubatin behaviur in castrated male dves (Stern & Lehrman, 1969; Stern, 1974). Other hrmnes, such as prlactin, were effective nly in maintaining but nt in inducing incubatin behaviur (Lehrman & Brdy, 1961). Lehrman's pstulate has recently been challenged by the bservatins f Silver & Buntin (1973) and Silver & Feder (1973) wh cncluded that changes in the prgesterne level are nt bligatry fr the inductin f incubatin behaviur in male ring dves. Finding that there was n testis weight change thrughut the breeding perid (R. Silver & C. Barbiere, unpublished), and that male ring dves shwed a basal level f prgesterne thrughut * Cntributin N. 169 frm the Institute f Animal Behavir, Rutgers University. 267

2 268 Mei-Fang Cheng curtship and incubatin (Silver, Rebulleau, Lehrman & Feder, 1974), the authrs further cncluded that endcrine factrs are nt necessary fr the initiatin f male incubatin behaviur, and that situatinal (nn-hrmnal) cues frm female behaviur, nest bwl and nest materials act in additive fashin t prduce incubatin behaviur in male dves (Silver, Feder & Lehrman, 1973). Only the frmer f these tw cnclusins (that endcrine factrs are nt imprtant in the inductin fincubatin behaviur) appears t be incmpatible r irrecncilable with Lehrman's pstulate, but these tw sets f data may simply illustrate different aspects f the same physilgical phenmenn. If endcrine factrs are nt imprtant in the inductin f incubatin behaviur, the prgesterne effect may be a pharmaclgical ne r the prgesternetreated dves may be t drwsy t shw any ther behaviur due t the general anaesthetic effect f prgesterne. The reasn fr a specific effect f prgesterne n incubatin behaviur is bscure, hwever, fr a dped dve has a chice f cruching cmfrtably in the crner r n the tp f the fd can in the testing cage ; the latter place is a favurite lcatin fr a rest. Further mre, it is yet t be shwn experimentally that the prgesterne-treated dves are under the influence f a general anaesthetic effect. An alternative view is that mst f the cnflicting findings simply result frm differences in experimental prcedure, i.e. in Lehrman's experiments, nly the internal endcrine make-up f the dves was varied by prgesterne injectins while situatinal cues were minimized by keeping the males and females in islatin until they were tested. Thus, the experiments were designed t shw the effect f prgesterne injectins, if any, n incubatin behaviur; the measurements taken were the number f dves that 'sat' in 24 r 48 hr and the latency t 'sit'. In the experiments f Silver and her c-wrkers, the internal endcrine make-up was varied by dexamethasne (DEX) administratins, while all situatinal cues were maximized; male dves were expsed t the females in the breeding cages befre and thrughut the perid f hrmne administratins and mst DEX treatments did nt start until eggs were laid. The measurement taken in these experiments was the amunt f time 'sitting' ver a testing perid f 15 days, i.e. Lehrman's testing perid was extended t 15 days, and the latency t 'sit' was nt measured at all. Thus, the experi ments were cncerned with the ability f the male dves t incubate after the blckade f prgesterne with DEX, when all situatinal cues were nrmal. Since experienced male dves d incubate in the testing prcedures f Silver & Buntin (1973) and Silver & Feder (1973), nn-hrmnal cues must still be the incubatin behaviur f such males fr half r adequate fr maintaining mre f the incubatin perid. The inductin f incubatin behaviur was very difficult t evaluate, hwever, because (1) with the exceptin f ne grup, DEX administratin did nt start until several days after pairs f male and female dves were intrduced int the breeding cages and the females laid eggs, in which case mst cmpnents f incubatin behaviur had already develped, and (2) the grup that received treatments 2 days befre pairing were nt castrated s that gnadal prgesterne might have been invlved in the inductin f incubatin behaviur in these birds.

3 Inductin f incubatin behaviur in male dves 269 If the hrmnal and situatinal cues (Lehrman, 1965) are regarded nt nly as imprtant cntributry factrs in the inductin f reprductive behaviur but als as cmplementary t ne anther in the sense that ne kind f cue manifests its specific effect whenever the ther is held t a minimum, the tw sets f data can be recnciled as illustrating different aspects f incubatin behaviur. Since nn-hrmnal cues were kept t a minimum in Lehrman's experiments, the effect n incubatin behaviur f physilgical was changes due t the exgenus prgesterne, while in Silver's experiments, the adequacy f nnhrmnal cues in maintaining the incubatin behaviur f experienced males was demnstrated, since the hrmnal state was upset by DEX. Sme f the experiments described belw were designed t answer the fllw ing questins. (1) Is a high dsage f prgesterne (100^g/day fr 7 days) really necessary in rder t demnstrate its behaviural effects? (2) Des prgesterne induce incubatin behaviur r des it induce ther behaviural patterns which precede and/r accmpany incubatin behaviur? (3) Des prgesterneinduced incubatin behaviur have any functinal effect, such as hatching eggs? MATERIALS AND METHODS Subjects The ring dves were hatched in the labratry f the Institute f Animal Behavir, Rutgers University, and were maintained under a light cycle f 14-hr light/10-hr dark (lights n hurs, ff hurs EST). Temperature was usually maintained between 21 and 22CC. At 21 days f age, the birds were transferred t stck cages which hused abut fifteen yung squabs. At 5 t 6 mnths f age, the birds were transferred t an islatin rm where each bird was hused in an individual cage (islatin cage) rack munted and measuring cm. Birds in such cages culd hear but nt see the ther birds. After 1 t 2 mnths in the islatin cage, each bird was put in a wden breeding cage measuring cm with wire-mesh drs. The bird was paired with a mate, given a nest bwl and nest materials and allwed t rear ne r tw squabs t 21 days f age. The pair were then separated and returned t the islatin cages. All birds bred successfully nce r twice and were kept in the islatin cages fr 3 t 5 weeks befre being used in these studies. Hrmne administratin All hrmnes were injected alternately int the right and left pectral muscles. Prgesterne. A ttal f fifty reprductively experienced male dves were treated daily with 10 µg, 25 µg r 100 µg prgesterne (Prlutn: Schering Crpratin, New Jersey, U.S.A.) in 0-1 ml sesame il fr 7 days in the islatin cages. As stimulus females, fifty-fur reprductively experienced female dves in the islatin cages were given 100 µg prgesterne daily during the same perid as the male dves. Each breeding cage was partitined int tw cmpart ments by a glass plate in the middle f the cage. A hand-made nest and tw

4 270 Mei-Fang Cheng sterile eggs were placed in each f these tw cmpartments. On the day fllw ing the last injectin, ne male dve was put in ne side f the cage and the stimulus female in the ther. The testing situatin used in these experiments differs frm thse f previus studies in that the male dve was separated frm the female but culd see her. At the end f prgesterne treatment, ten male dves (five received 100 µg and five received 25 /ig/day fr 7 days) were killed and the testes were remved fr histlgical study. T test whether 100 µg prgesterne/day fr 7 days was an excessive dse, six male dves were given 100 µg prgesterne/day fr 2 days and tw male dves were given 200 µg prgesterne fr 1 day; all these birds were tested exactly as thse in the first grup. In the 'hatching success' experiment, five birds were treated with 25 ^g prgesterne/day fr 7 days and were prvided with fertile eggs laid by ther breeding dves. One f the tw sterile eggs was remved at the end f a 24-hr bservatin perid and ne fertile 1- t 3-day-ld egg was replaced. Dexamethasne. T test the hypthesis that situatinal cues and hrmnal cues are cmplementary t each ther, male dves were deprived f prges terne and allwed n access t the females until the time f the incubatin test. The incubatin test cnsisted f intrducing a nest with tw eggs and a female dve treated with 100 ^g prgesterne/day. The anticipated result wuld be that these birds wuld nt respnd t the test situatin by sitting n the eggs within a perid f 24 t 48 hr, since bth situatinal and hrmnal cues wuld be minimized. After a prlnged assciatin with female dves, hwever, the male dves shuld shw sme incubatin behaviur which wuld be induced by an increased level f situatinal cues. Ten male dves in islatin cages were given 100 µg DEX daily fr 7 days. On the day fllwing the last injectin, five birds were subjected t a testing prcedure which was identical t that used fr the prgesterne-treated birds, while the ther five birds were killed t determine the weight f their testes. T check if the findings fr DEX-treated birds culd be attributed t the small number f birds tested, anther ten pairs f male and female dves were used. Bth male and female dves in islatin cages were given 100 ^g DEX/day fr 7 days. After the last injectin, they were placed in pairs in the breeding cages withut the glass partitins and were bserved daily fr 15 days. The birds were then killed and their testes and varies were examined at autpsy. Samples f testes frm fur birds were stained with haematxylin and esin fr in these tissues. subsequent examinatin f the mrphlgical changes Cntrl birds. As a cntrl grup, ten male dves were given injectins f 0-1 ml sesame il/day fr 7 days and were als tested fr incubatin behaviur. Anther five intact birds were used fr the determinatin f testis weight in nrmal male dves maintained in the islatin rm and expsed t 14-hr light/day fr 3 t 5 weeks. Finally, five male dves were castrated and similarly tested 2 weeks after surgery. This grup prvided data fr cmparisn with the DEX-treated grup. Behaviural bservatins. Observatins were cnducted n each pair fr the first hur after pairing. Further bservatins (fur r five 20-min visits a day) were made ver a 2- t 4-week perid. The bservatins included (1) latency

5 Inductin f incubatin behaviur in male dves 271 f'sitting', (2) the number f birds 'sitting', (3) the number f nests destryed, (4) the behaviur patterns preceding and during 'sitting' in the nest, and (5) the hatching success fr prgesterne-treated birds. RESULTS Dsage fprgesterne and incubatin respnse Exgenus injectins f 10 ^g prgesterne/day fr 7 days were still effective in inducing incubatin behaviur (see Table 1). This was reflected in the shrter latency and the lwer incidence f nest-destructin cmpared t the cntrl grup (i.e. the il-treated birds). Of the dsages used in the first grup, 25 ^g/day fr 7 days was fund t be the mst effective. Fur f the six male dves treated with 100 µg prgesterne/day fr 2 days nly shwed incubatin behaviur within 48 hr (Table 1), but male dves receiving 25 µg prgesterne/ day fr 2 days failed t shw incubatin behaviur within 48 hr. A single injec tin f 200 µg prgesterne induced sme spradic nest-cing in the nest bwl but this did nt develp int incubatin behaviur. Nest-cing in the nest bwl The display f nest-cing in the nest-bwl nrmally preceded the nset f incubatin behaviur. This was true fr the prgesterne-induced as well as the naturally ccurring incubatin behaviur. The nly difference between these tw grups was the latency f displaying the behaviur pattern. The prgester ne-treated birds shwed behaviur patterns sner than did the cntrls; the latter spent the first few hurs, r even days, displaying either behaviur patterns which were characteristic f earlier curtship, such as bw-cing and hpcharging, r ther behaviur patterns which were nt directed t the female mates. Hatching success Fur f the five fertile eggs given t the prgesterne-treated birds were hatched and three squabs were raised successfully; their weight gains cmparable were t thse raised by nrmal parents. It is difficult t judge the signi ficance f these hatching rates as the male dves were separated frm females by a glass plate and were carrying alne the burden f incubating the eggs and feeding the yung squabs. Dexamethasne treatments and incubatin behaviur The incubatin respnses f the DEX-treated and castrated male dves are shwn in Table 1. Nne f the DEX-treated birds shwed incubatin behaviur within 24 t 48 hr. Even after 2 weeks f expsure t the female dves, nly ne male dve 'sat' and the rest did nt. These male dves behaved very much like the castrated males (see Table 1 ). Their physical appearance, hwever, differed frm that f the castrated dves in that their bdy feathers fluffed up t such an extent that the males lked like rund balls. The DEX-treated birds failed t display any curtship behaviur. All the birds had shrunken atrphic testes r varies. The histlgical preparatins

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7 Inductin f incubatin behaviur in male dves 273 revealed shrinkage f the seminiferus tubules. Table 2 gives the weights f the testes f thse prgesterne-treated, DEX-treated and intact birds btained at the end f seven treatments. Table 2. The testicular and bdy weights f male ring dves in different treatment grups Weight f paired testes (mg) Bdy weight (g) Intact males in islatin (N= 10) Prgesterne (25 Mg/day) fr 7 days (A"-5) ± Prgesterne (100 Mg/day) fr 7 days (N=5) ±9-2 DEX (100 Mg/day) fr 7 days (N = 10) ±20-7** * Values are expressed in terms f mean + S.E.M. Cmparisns between grups were made using the Duncan's test fr unequal n. DEX = dexamethasne; = number f dves. ** P<0-01 ;*P<0-05. DISCUSSION The results f the present experiments indicate that (1) the accumulated rather than the daily dse level f prgesterne injectins appears t be the determin ant factr in mediating behaviural effects. The ptimal (accumulated) dsage prbably is f the rder f 200 µg, (2) The level f prgesterne at the dsage used in the earlier studies (100 µg/day fr 7 days) is indeed nn-physilgical, and (3) the behaviural effect f prgesterne is unlikely t be due t any anaesthetic prperties, since 25 µg/day fr 7 days r 100 µg/day fr 2 days are mre effective than 100 µg/day fr 7 days. In rder t gain a fuller understanding f the rôle f prgesterne in induc tin f the incubatin behaviur f male ring dves, it is imprtant t have sme knwledge f the preceding behaviural patterns. These may be cate grized int fur stages: (1) aggressive behaviur bw-cing and hpcharging; (2) nest-sliciting (wing-flipping and cing in an blique psture at the ptential nest site) and cpulatry behaviur; (3) nest-building and nestcing behaviur (wing-flipping and cing in a partly cruched psture in the nest-bwl with the tail smewhat lwered) ; (4) 'sitting' in the nest wingflipping r nest-cing ccasinally. When the nest is ccupied by the female, the male usually perches quietly near the nest, ccasinally heterpreening her. Stage 4 is fllwed by egg-laying and subsequent incubatin by bth sexes. The behaviural cmpnents f Stage 4 usually cnsist f (a) rearranging the nest materials, (b) cmpnents f settling mvements, (c) expsure f the midline apterium area as the dve arises frm the nest, (d) mild nest-defensive behaviur, and (e) ccasinal nest-cing r wing-flipping. During incubatin, bth sexes display all these behaviural cmpnents with even greater intensity. They als shw behaviural cmpnents specifically assciated with the presence f eggs. Thus, Stage 4 may be regarded as a stage f 'pseud-incuba tin' (incubatin withut eggs). The presence f eggs apparently des nt

8 274 Mei-Fang Cheng in the nest and the behaviural transitin frm curtship t incubatin may, therefre be regarded as a cntinuus prcess. This is supprted by the bservatin that bth male and female dves culd be induced t incubate eggs even befre their cause any abrupt behaviural change in a dve which has been 'sitting' wn eggs were laid, prvided that the fster eggs were given t them during the last part f the pre-laying perid (Lehrman, Brdy & Wrtis, 1961). Since the behaviural data needed t determine the stage f male curtship were nt given by these authrs, it is nt pssible t tell at which behaviural stage their dves were prvided with fster eggs. The best results were usually btained, hwever, with thse dves which had been paired fr 5 t 8 days, and therefre the behaviural stage was prbably either Stage 3 r Stage 4. Prgesterne appeared t facilitate the ccurrence f the behaviural patterns characteristic f Stage 3, i.e. nest-cing in the nest in a partly cruched ps ture. The cntrl dves injected with the vehicle alne did nt shw these behaviur patterns until much later (see Table 1). Their initial behaviur patterns were thse characteristic f early curtship, i.e., Stage 1 and/r Stage 2 behaviur. Since all birds tested in the experiments reprted in this paper were prvided with fully cnstructed nests, it is nt surprising that they failed t shw nest-building behaviur (White, 1974). It may be cncluded that treatment with prgesterne facilitates an incuba tin respnse by way f inducing nest-related activities. It shuld be emphas ized, hwever, that this cnclusin des nt necessarily imply the existence f a parallel functin f endgenus prgesterne. Endgenus prgesterne may have an excitatry effect n behaviur depending n its differential rati with respect t the levels f ther hrmnes (such as teststerne), which may fluctuate during the breeding cycle. There is als a pssibility, hwever, that prgesterne secretin may surge (r fluctuate) at a time which was nt sampled in the previus studies f ring dves. Since the mst effective hrmne regimen fr inducing an incubatin respnse in the castrated dves is the cmbined treatment with teststerne (r estrgen) and prgesterne (Stern & Lehrman, 1969; Stern, 1974), the underlying mechanism fr incubatin behaviur seems t be the synergistic tw hrmnes. effect f the In a recent study, Krenbrt, Schmberg & Ericksn (1974) shwed that the plasma estrgen level f the female ring dve rises immediately after male curtship, reaching a peak in a few days and then beginning t decline arund the time f the nest-building perid. If the teststerne level in the male ring dve changes in a similar manner during the breeding cycle, it is cnceivable that when it drps t a critical pint, the prgesterne, which is at a relatively lw and steady level, may then interact synergistically with the teststerne t prduce the behaviural effect. It is a well-established fact that the synergistic effect f prgesterne and estrgen is best manifested when the estrgen level is relatively lw (Masn, 1952; Lisk, 1971 ; Diakw, Pfaff & Kmisaruk, 1973). The finding that nne f the DEX-treated dves in the present study shwed 'sitting' behaviur within a 2-week perid is in favur f the hypthesis that hrmnal and nn-hrmnal (situatinal) cues are cmplementary t ne anther fr the inductin f incubatin behaviur in ring dves and cntrary t

9 Inductin f incubatin behaviur in male dves 275 f Silver and her c-wrkers. The effect in t the expectatins arused by the findings ptimal dse f DEX which is sufficient t achieve an ACTH-blcking ring dves but nt t strng t cause ther side effects has nt s far, hwever, been determined. Depending n the relative imprtance f hrmnal and situatinal cues in a given experimental situatin, there are fur cnditins which can be tested experimentally with ring dves t illustrate the cmplementary rôle f these cues. The cnditins are summarized in Table 3. The first three have been Table 3. Cmplementary rôle f hrmnal and situatinal cues in the inductin f male incubatin behaviur in ring dves Cnditins Hrmnal cues Situatinal cues Incubatin behaviur Experimental studies Max Min Min Max Min Max Min Max Yes Yes N Yes Max = maximized; Min = minimized. Lehrman et al. (1958, 1961), Stern et al. (1969, 1974) Silver et al. (1973, 1974) Present study Predictin discussed in the present paper. The utcme f the furth cnditin hardly and the seems in questin. Since we knw already frm Lehrman's study present findings that prgesterne injectins (maximized hrmnal cues) have the effect f shrtening the time it takes t induce incubatin behaviur in a shrt testing prcedure (minimized situatinal cues), it fllws that, in an extended testing prcedure (maximized situatinal cues), prgesterne injec tins shuld have the same effect n the inductin f incubatin behaviur. One interesting cnsideratin is the pssibility f cntrlling the inductin f incuba f these tw kinds f tin behaviur by manipulating the relative imprtance cues. The rôle f sexual experience in mdifying the relative imprtance f hr mnes in eliciting sexual behaviur has been demnstrated by Rsenblatt & Arnsn (1958) in their study f the cpulatry behaviur f castrated male cats. We hpe t examine the pssible rôle f such a factr in the cmplementary relatinships f hrmnal and situatinal cues in the inductin f the incuba tin behaviur f male ring dves. Finally, since weather, fd and predatrs are imprtant factrs influencing the incubatin behaviur f herring gulls in the field (Drent, 1967), it seems reasnable t assume that they are imprtant situatinal cues fr the incubatin behaviur f dves under natural cnditins. ACKNOWLEDGMENTS This paper is dedicated t the memry f the late Daniel S. Lehrman, Prfessr f Psychlgy and Directr fthe Institute fanimal Behavir, Rutgers Univer sity, Newark, New Jersey. Prfessr Lehrman was a spirited scientist and his students and clleagues were always encuraged t be critical f his wrks. 1

10 276 Mei-Fang Cheng thank Dr W. K. Cheng fr his critical reading f this manuscript and many suggestins. I als thank Miss Mabel My fr her assistance in behaviural bservatins. This wrk was supprted by USPHS Grant MH t D. S. Lehrman (deceased) and M.-F. Cheng, and by a grant frm Alfred P. Slan Fundatin. A preliminary reprt f the present study was presented by the authr at the Eastern Reginal Reprductive Cnference in Chicag n 31 May REFERENCES Diakw, C, Pfaff, D. & Kmisaruk, B. (1973) Sensry and hrmnal interactins in eliciting lrdsis. Fedn Prc. Fedn Am. Scs exp. Bil. 32, 214. Drent, R. H. (1967) Functinal aspects f incubatin in the herring gull (Larus argentatus Pnt.). Behaviur, Suppl. 17, Krenbrt, C. C, Schmberg, D. W. & Ericksn, C. J. (1974) Radiimmunassay f plasma estradil during the breeding cycle f ring dves (Streptpelia risria). Endcrinlgy, 94, Lehrman, D. S. (1958) Effect f female sex hrmnes n incubatin behavir in the ring dve (Strept pelia risria). J. cmp. physil. Psychl. 51, Lehrman, D. S. (1961) Hrmnal regulatin f parental behavir in birds and infra-human mammals. In Sex and Internal Secretins, pp Ed. W. C. Yung. Williams & Wilkins, Baltimre. Lehrman, D.S. (1965) Interactin between internal and external envirnments in the regulatin f the reprductive cycle f the ring dve. In Sex and Behavir, pp Ed. F. A. Beach. Wiley, New Yrk. Lehrman, D. S. & Brdy, P. (1961) Des prlactin induce incubatin behaviur in the ring dve? J. Endcr. 22, Lehrman, D. S., Brdy, P. & Wrtis, R. P. (1961) Gnadtrpin secretin in respnse t external stimuli f varying duratin in the ring dve (Streptpelia risria). Prc. Sc. exp. Bil. Med. 95, 373. Lisk, R. D. (1971) Oestrgen and prgesterne synergism and elicitatin f maternal nest-building in the muse (Mus musculus). Anim. Behav. 19, Masn, R. C. (1952) Synergistic and antagnistic effects f prgesterne in cmbinatin with estrgens n viduct weights. Endcrinlgy, 51, Rsenblatt, J. S. & Arnsn, L. R. (1958) The influence f experience n the behaviral effects f andrgen in prepuberally castrated male cats. J. Anim. Behav. 6, 171. Silver, R. & Buntin, J. (1973) Rle f adrenal hrmnes in incubatin behavir f male ring dves (Streptpelia risria). J. cmp. physil. Psychl. 84, 453. Silver, R. & Feder, H. H. (1973) Reprductive cycle f the male ring dve. II. Rle f gnadal hrmnes in incubatin behavir. J. cmp. physil. Psychl. 84, 464^171. Silver, R., Feder, H. H. & Lehrman, D. S. (1973) Situatinal and hrmnal determinants f curt ship, aggressive and incubatin behavir in male ring dves (Streptpelia risria). Hrm. & Behav. 4, Silver, R., Rebulleau, C, Lehrman, D. S. & Feder, H. H. (1974) Radiimmunassay f plasma prgesterne during the reprductive cycle f male and female ring dves (Streptpelia risria). Endcrinlgy, 94, 437^144. Stern, J. M. (1974) Estrgen and incubatin in male ring dve. J. cmp. physil. Psychl. (in press). Stern, J. M. & Lehrman, D. S. (1969) Rle f teststerne in prgesterne-induced incubatin behaviur in male ring dves (Streptpelia risria). J. Endcr. 44, 13. White, S. J. (1974) Effects f stimuli emanating frm the nest in the reprductive cycle in the ring dve (Streptpelia risria). II. Building during the pre-laying perid. Anim. Behav. (in press).