Vol.•94• •8] J NmzAND T• PZLKWYK,Enemy Recognition bySong Sparrow 195 ENEMY RECOGNITION BY THE SONG SPARROW BY MARGARET M. NICE AND JOOST TER PELKWYK Plate 8 IN connectionwith the study of inborn and learned behavior in the SongSparrow (Melospiza melodia) an attemptwas made to ex- periment on fear reactionsin hand-raisedbirds, particularlyon the questionas to what it is that constitutesan 'enemy'to thesebirds. The SongSparrow is a favorablesubject for testsbecause the num- ber of notes,either of 'alarm' or 'fear,' varieswith the degreeof ex- citement. In this we have an objectivecriterion of the degreeoœ fear. Hand-raisedGoldfinches (Spinus tristis), on the other hand, were either indifferentwhen tested,or flew wildly about the cage;it was easyto seewhat frightenedthem, but impossibleto make a com- parative study of the effectivenessof different stimuli. As stimuli in our tests we used live animals, mounted birds, and cardboard models. For the loan of the mounted birds we wish to thank Mr. E. R. Blake and Mr. Rudyerd Boulton of the Field Mu- seum of Natural History, Mr. Charles Rogers of Princeton Uni- versity,and Mr. Earl Wright of the ChicagoAcademy of Sciences. OBSERVATIONS BY OTHERS Severalexperimental approaches have recently been made to an analysisof the predator-preyrelation from the standpointof the predator (Tinbergen,1940); but often the assumptionseems to have been that the prey is passive.We know, however,that the prey has its specialmethods of defense,such as threatening,flight, hiding, or makinguse of protectivecoloration. Observationsand experiments on enemyrecognition are scattered. Bolles (1890) carrieda captive Barred Owl (Strix varia) into the woodsand recordedthe reactions of the birds towardit; the majorityof the birds "scolded"it, doing somore vigorously in summerthan in winter. Thomdike (1899)ex- perimentedon instinctivereactions of young chicks,finding no in- stinctivefear of cats. "There developsin the first month a general fear of novel objectsin motion." A tame Carrion Crow (Corvus corone)and Jackdaw(Corvus monedula) were noted by Hertz (1926) to reactto everynew object with fear,but assoon as the objectproved 196 N•c•AnD T•R P•LawYa,Enemy Recognition bySong Sparrow L[-Auk April to be harmless,the fear changedinto curiosityand after that to ag- gressiveness.Various creatures were put into a cagewith a "hungry chickensnake" by Kellogg (1931); fear was shownby wild adult EnglishSparrows (Passer domesticus), but none by an adult Canary, nor by chicksless than a week old. The fear of snakesis often assumedto be inborn. Experimentsby Antonius (1939)show, how- ever,that the well-knownsnake-fear in apesand monkeysis probably not inborn,but learnedfrom companions.No inborn fear of snakes wasfound by Rand (1937)in two hand-raisedBlue Jays (Cyanocitta cristata);a dogwas at first ignoredby the birds,but after one was38 daysold, it flew up out of the dog'sreach. Brfickner (1933) states that very young chickswere afraid only of loud noisesand of the lossof balance. Toward rabbits they behavedindifferently at first, but at the age of three weeksthey reactedwith distinct fear. There are a numberof experimentsusing birds of prey or models of the same. Lorenz (1935: 356) mentionsthe violent reactionof a hand-raised Passer domesticus to the first owl the bird ever saw; he statesthat the Magpie (Pica pica) instinctivelyrecognizes a preda- tory animal,but that the Jackdaw,that livesin flocks,does not. A mountedowl (Asio otus) and hawk (Accipiter)provoked fear in a tame Hooded Crow (Corvus cornix) and hand-raisedJackdaws (Strausz,1938). Plastermodels of the headsof thesebirds, painted or white, alsoprovoked fear when the headlooked in the direction of the Crow or Jackdaw. The birds were much lessdisturbed when the mountsand modelshad their backsturned. A mountedJack- daw arousedcuriosity or was ignored. Although the effectof the mountedowl and hawk was very great at first, after repeatedex- perimentsor if the objectswere left for sometime in the cage,the birds graduallybecame indifferent. Kr•itzig (1939)found in young of the Hazel Hen (Tetrastesbonasia rupestris) no signsof fear be- fore the ageof ten days;after that theyshowed marked fear reactions to dogsand hawks. Goethe(1937), Tinbergen (1939),Lorenz (1939) and Kr•itzig (1940)describe experiments in which cardboardmodels of variousshapes were movedthrough the air alongwires. Goethe noted a specificreaction in young Blackcocks(Lyrurus tetrix) to modelsof birds of prey; there was a sexualdifferentiation in chicks as young as twenty days, the femalesseeking cover, the males as- suminga defensiveattitude. The experimentsof Lorenz and Tin- bergenshowed that youngGrey Geese(Anser anser) react from about the eighth week on; the form of the model was not as important with thesebirds and with ducklingsas with youngTurkeys (Meleagris THE AUK, VOL. 58 PI,ATE }q Fro. I.--Attitu(les ()f' Song ."il)arrowin alarm. fcau and fright. From lef! to iigh! (Ul)l)el r(m-): I. miniarmed: '2. ale[t: 3. turning head to h)()k: I. 5. :illlB'in (l¾illg•,alld tail fill)peal): strong alnrm; 7. fear: 8. fright (panting). I Fit;. 2.--Cardl)oard models of oxvls. I"lom lett I{) right: I. model at half scale; 2, 'head' model: 3. 'l)csl' model; 4, 'head' model xxilhmtt c,xcs;5, 'outline' of 'head' model; 6. model with shading on the sides. Vol.194158'] .J NICEAND TER PELKWYK, Enemy Recognition bySong Sparrow 197 gallopavo)and Kr/itzig'sRock Ptarmigans(Lagopus mutus). With both thesespecies a modelwith a shortneck and long tail (Acci- piter) provokedstrong fear reactions,but the samemodel was largely ignoredwhen pulled overheadwith the long end forward (goose). Young hand-raisedptarmigans were frightenedby a live dog, but paid no attention to modelsof mammals. Kelso (1940) found that youngScreech Owls (Otus asio)showed fear at the sightof the skin of a Crow (Corvusbrachyrhynchos) when it wasmoved. In a letter Mrs. Amelia Laskeydescribes some observations made on a hand-raisedMockingbird (Mimus polyglottos):"Jan. 11, he fights everythingthat comeshis way including the dog, his shadow,his reflection,and other birds that I hold near him exceptinga dead ScreechOwl. To that he givesa pronouncedfear reaction,flying in frightened,fluttering manner as far back in his cageas possible when he seesthe owl. He attackeda SparrowHawk throughthe wire." On June 11, she wrote: "When I had the Saw-whetOwl (Cryptoglauxacadica), he showedfear of it. One eveningthe owl was free in the room and flew to a perch abovethe Mockingbird's cage. The Mockingbirdcraned his neck repeatedlyto watch the owl who wasfour feet abovehis cage,giving sharp staccato chi-chick callsrepeatedly. The owl bent its head a numberof timesto look at the Mockingbird,but showedno specialinterest even when the room lights were dimmed. After the owl was taken out of the room all lightswere switched off. In aboutten minutesthe Mockingbird beganto give the staccatocalls again. I went quicklyto the room, turned on bright lights and saw the Mockingbirdcrane his neck and turn his headsideways looking toward the spotwhere the owl had perched." A curiousphenomenon has been mentionedby the Heinroths (1924-32),namely, that somebirds are afraid of colors,some of blue, others of red. Among the former they cite one of a brood of five Red-backedShrikes (Lanius collurio), three of a broodof five Gray Wagtails (Motacillafiava), a Jackdaw,a Yellowhammer(Emberiza citrinella) and a Cockatoo. Tree Pipits (Anthus trivialis) were afraid of red. A pair of Goldfinches,taken from the nest at the age of two days by Wm. E. Schantzand later brought to Chicago, were afraid of a dark-bluebox top, flying wildly in the cagewhen- ever it was shown. They fearedsome other blue objects,but not miscellaneousobjects of other colors. Another pair raised by Mr. Schantz,showed fear only to black paper. In our experimentswith SongSparrows we did not observea fear for any color. 198 NInEa•D T•et• Pr_J•KW'VK, Enemy Recognition bySong Sparrow 1I-Auk April Bm•Av•oR oF XHE SONG S•'•ROW Three chiefstages of fear maybe distinguishedin the SongSparrow: Stage Note Postures tchunk Crest raised; tail raised and flipped; wingsflipped; restlesschange of location. tik Featherscompressed; neck elongated; body crouched. 'Fright' tik-tik-tik Flies and hides; flutters in attempt to escape;pants with open bill. These categoriesshow 'alarm,' 'fear' and 'fright' in their extreme form; in milder casessome of the characteristicsare not shown. In the first stageall characteristicsexcept the raisedcrest may be dis- playedseparately in situationsthat are obviouslynot concernedwith alarm. The note tchunk is the 'ordinary' note of the male Song Sparrowon his territory,and is seldomheard from the femaleex- ceptin the nestingseason; it is typicallygiven by her directlyafter shehas left the nestduring incubationand more vigorouslyin con- nection with the approachof an enemy to the nest. It often seems to have an element of 'protest' in it. Sometimesit seemsto be givenby the male as a matter of 'self-assertion.'(With the hand- raisedmales it is often given while bathing; here it might be inter- preted as vocal self-assertionwhile temporarilyhampered by wet feathers.) It appearsto be analogousto the 'rain-call'of the Chaf- finch (Fringilla coelebs),as describedby Sick (1939), which often expressesdiscomfort or anxiety,and alsoappears to be a specialex- pressionof territoryadvertising. Wing- and tail-flippingmay accompany'pleasurable' excitement, as when the pair hunt for a nestingsite. Raising the crestnearly alwaysappears to expresssome alarm or apprehension.It hasbeen characteristicof the underling male with the hand-raisedbirds. The rhythm with which the notesare givenand the speciesof note vary with the degreeof excitement.To illustratethis, three ex- ampleswill be givenwith wild SongSparrows in Massachusettsin 1940. June 12: the observerin searchingfor a nestwhich contained newlyhatched young came within a few metersof it; the female gave48 tchunksand five tiks in one minute. The observerleft, walked 50 metersand hid; the bird then gave 32 tchunksin a minute. Two days later when the nest was visited, the female 'gave56 tchunksin a minute;as soonas the observerwas out of sightshe gave 35 in a minute.