Mechanisms of avian egg recognition: Which egg parameters elicit responses by rejecter species?
- 113 Downloads
Some species of North American passerines nearly always reject nonmimetic eggs placed in their nests and have apparently evolved this behavior in response to brood parasitism. Experiments presented here examined the specific egg parameters to which ‘rejecter species’ respond, the relative tolerances rejecters show towards nonmimetic eggs and the degree to which rejection is limited to eggs of the brown-headed cowbird (Molothrus ater), the only parasitic bird widespread in North America.
Relative to cowbird eggs, American robin (Turdus migratorius) eggs are larger, blue rather than white and immaculate rather than spotted. Experiments using 10 egg models at 137 nests showed that robins respond to each of these differences (Figs. 2 and 3) but do not usually reject an egg that deviates from their own by only one difference. Eggs that differ in ant two of the three parameters are usually rejected. This built-in tolerance reduces the likelihood that robins will reject their own eggs if these are atypical in size or coloration.
Small egg size was the most important parameter eliciting rapid rejections (i.e. within 1 day), probably because differnces in size can be detected by both visual and tactile perception. By contrast, small egg size was the least important parameter determining whether eggs were eventually rejected (i.e. within 5 days, Tables 2 and 3). In terms of their eventual response, robins may be more sensitive to egg coloration than to size because the latter parameter is less reliable in distinguishing between robin and cowbird eggs.
Experiments were also carried out at 37 nests of the gray catbird (Dumetella carolinensis), whose immaculate blue-green egg is only slightly larger than a cowbird egg. Catbirds are much more responsive to white ground color than to maculation (Table 4), perhaps because color is more reliable in distinguishing between catbird and cowbird eggs.
Rejecter species exhibit degrees of tolerance towards foreign eggs that are proportional to the divergence between their eggs and those of the cowbird. Birds with eggs strongly divergent from cowbird eggs benefit from being relatively tolerant because they avoid rejecting their own eggs but still act against cowbird eggs. Species with cowbird-like eggs must be relatively intolerant to maximize the chances that cowbird eggs are rejected.
Experiments show that rejection is not specific to cowbird eggs. Thus, birds have apparently responded evolutionarily to brood parasitism by developing recognition of their own eggs, rather than by developing recognition and rejection specific to parasitic eggs.
KeywordsBrood Parasitism Tactile Perception American Robin Parasitic Bird Rapid Rejection
Unable to display preview. Download preview PDF.
- Alvarez F, Arias De Reyna L, Segura M (1976) Experimental brood parasitism of the magpie (Pica pica). Anim Behav 24:907–916Google Scholar
- Baerends GP (1959) The ethological analysis of incubation behaviour. Ibis 101:357–368Google Scholar
- Beach FA (1942) Analysis of the stimuli adequate to elicit mating behavior in the sexually inexperienced rat. J Comp Psychol 33:163–207Google Scholar
- Bent AC (1948) Life histories of North American nuthatches, wrens, thrashers and their allies. US Natl Mus Bull 195:1–475Google Scholar
- Bent AC (1949) Life histories of North American thrushes, kinglets, and their allies. US Natl Mus Bull 196:1–452Google Scholar
- Bent AC (1958) Life histories of North American blackbirds, orioles, tanagers, and allies. US Natl Mus Bull 211:1–549Google Scholar
- Bower TGR (1966) Heterogeneous summation in human infants. Anim Behav 14:395–398Google Scholar
- Curio E (1969) Funktionsweise und stammegeschichte des flugfeinderkennes einiger Darwinfinkin (Geospizinae). Z Tierpsychol 26:394–487Google Scholar
- Finney DJ (1952) Statistical method in biological assay. Griffin, LondonGoogle Scholar
- Friedmann H (1929) The cowbirds, a study in the biology of social parasitism. Thomas, Springfield, IllinoisGoogle Scholar
- Friedmann H (1963) Host relations of the parasitic cowbirds. US Natl Mus Bull 233:1–276Google Scholar
- Friedmann H, Kiff LF, Rothstein SI (1977) A further contribution to knowledge of the host relations of the parasitic cowbirds. Smithson Contrib Zool 235:1–75Google Scholar
- Munsell book of color, neighboring hues (1965) Munsell, Baltimore, MarylandGoogle Scholar
- Poulsen H (1953) A study of incubation responses and some other behaviour patterns in birds. Vidensk Medd Dan Naturhis Foren (Khobenhavn) 115:1–131Google Scholar
- Reed CA (1965) North American birds' eggs, revised edn. Dover, New YorkGoogle Scholar
- Romanoff AL, Romanoff AJ (1949) The avian egg. Wiley, New YorkGoogle Scholar
- Rothstein SI (1970) An experimental investigation of the defences of the hosts of the parasitic brown-headed cowbird (Molothrus ater). Ph D dissertation, Yale Univ, New Haven, ConnecticutGoogle Scholar
- Rothstein SI (1974) Mechanisms of avian egg recognition: possible learned and innate factors. Auk 91:796–807Google Scholar
- Rothstein SI (1975a) An experimental and teleonomic investigation of avian brood parasitism. Condor 77:250–271Google Scholar
- Rothstein SI (1975b) Evolutionary rates and host defenses against avian brood parasitism. Am Nat 109:161–176Google Scholar
- Rothstein SI (1975c) Mechanisms of avian egg recognition: Do birds know their own eggs? Anim Behav 23:268–278Google Scholar
- Rothstein SI (1976a) Cowbird parasitism of the cedar waxwing and its evolutionary implications. Auk 93:498–509Google Scholar
- Rothstein SI (1976b) Experiments on defenses cedar waxwings use against cowbird parasitism. Auk 93:675–691Google Scholar
- Rothstein SI (1977) Cowbird parasitism and egg recognition of the northern oriole. Wilson Bull 84:21–32Google Scholar
- Rothstein SI (1978) Mechanisms of avian egg recognition: additional evidence for learned components. Anim Behav 26:671–677Google Scholar
- Rothstein SI (1982) Successes and failures in avian egg and nestling recognition with comments on the utility of optimality reasoning. Am Zool 22:547–560Google Scholar
- Scott DM (1977) Cowbird parasitism on the gray catbird at London, Ontario Auk 94:18–27Google Scholar
- Seitz E (1942) Die paarbildung bei einigen cichliden. Z Tierpsychol 5:221–251Google Scholar
- Siegel S (1956) Nonparametric statistics for the behavioral sciences. McGraw-Hill, New YorkGoogle Scholar
- Tschanz B (1959) Zur Brutbiologie der Trottellumme (Uria aalge aalge). Behaviour 14:1–100Google Scholar
- Yates F (1965) Sampling methods for censuses and surveys, 3rd edn. Griffin, LondonGoogle Scholar