BIO 555/755
Behavioral Ecology

Cooperation & Helping

Cooperative Breeding in Vertebrates

    Higher vertebrates:

    Cooperative breeding:

Monadjem, A.  Cooperative breeding in southern African passerines and brood parasitism: Is there a relationship?  South African Journal of Science 92:295.

 In order for an obligate avian brood-parasitic species to lay eggs, the species must first locate the nest of the host species.  Tests have been done to see if cooperative breeders are more easily detected and attract brood parasites.

Results -- Out of 187 passerine species with 21 south African bird species as brood parasites:

Conclusion -- The detectability of the nest only plays a minor role in the passarine species.  Species with easily detectable nests but with good egg discrimination, are poor hosts to the brood parasite.  This may be the reason for the lack of association between breeding system and brood parasitism.

                                                                                                                                               Submitted by Andrea Pinkston

Do helpers really help? Is there any correlation between the presence of helpers and the production of young?

Silver-backed Jackal (Moehlman 1979)

White-fronted Bee-eater (Emlen 1981)

Helpers may contribute to increased survival of young by providing:

Silver-backed Jackal 
(feeding rate = no. of regurgitations and/or 'nurses' provided to litter of pups/hour)

White-fronted Bee-eater 
(feeding rate = total number of insects brought to young per hour when nestlings were 14 - 22 days old)

Experimental evidence - Brown et al. (1982):

Helpers DO help in babblers & in many other species, and breeders are the beneficiaries. But, what about the helpers? Do they also benefit or would they be better off leaving the group?

Why don't helpers breed on their own?

Types of constraining factors:

Test of the contraints model:

(Ecological constraint = log of total rainfall occurring in the month preceding breeding)

Why do helpers help?

Helping Behavior in Birds:

Trombino (1999) - Interspecific and intraspecific helping behavior within Sapsuckers (Sphyrapicus spp.)

Interspecific and intraspecific helping behavior have been previously recorded in birds, but are uncommon and rare (2.4% of bird species exhibit intraspecific helping behavior).


Conclusion:                                                                                                                                                         Contributed by Ben Sutter

Christman and Steven (1998) –  Adult Bridled Titmice (Baeolophus wollweberi) were assisted by individuals of the same species, which were hatching year and after hatching year birds.


Conclusion:                                                                                                                                                             Contributed by Ben Sutter

When do helpers become communal reproductives?

    Why do helpers not always reproduce communally within their groups?

Mendres, K A., and F.B. M. De Waal.  2000.  Capuchins do cooperate: the advantage of an intuitive task.  Animal Behaviour 60: 523-529.

Most studies have examined ultimate reasons for cooperation, these researchers looked at a proximate reason (cognitive mechanism) for cooperation in Capuchin monkeys (Cebus apella).  In the wild and captivity, these monkeys will share food with other individuals (both infants and adults).  So, they tested the Capuchin’s cooperation in acquiring food.


Results: Conclusions -- Capuchins communicate with each other (like glancing) and cooperate in order to acquire food – even if only one individual would get the food.  When an individual could acquire food alone, he/she would not solicit help from the partner.

                                                                                                                                                    Contributed by Heather Brace

Social factors determine cooperation in marmosets (Werdenich and  Huber 2002) --Marmosets (Callithrix jacchus) were trained to pull a handle to reach a food container.  In the first phase (dyadic training) each partner could solve the task alone, while the second phase (cooperation test) used a modified apparatus whose successful handling required the assignment of roles and synchrony of actions.  

   Each monkey was paired with both a cagemate of the same sex and of the opposite sex as well as with a dominant and subordinate partner.  Dyadic Training:  The “producer” was the individual who made the food accessible by pulling the string, whereas the “scrounger” needed only to grasp the reward.  Cooperation Test:  One partner had to pull the string while the second partner could easily obtain a piece of food by pushing away the lid as soon as the bowl was close to the wire mesh.
Results: Dyadic Training:  All subjects except one took different roles with different partners.  Fourteen of the 16 dyads showed a clear dominance relationship. 
Cooperation Ability:  All eight subjects showed successful cooperative behavior.

Factors Causing Cooperation:  The four dyads that were successful in the cooperation test were those in which the subordinate partner was the producer and the dominant partner was the scrounger in the dyadic training.  Dominant partners of cooperative dyads did not obtain more rewards than subordinate ones. 

                                        --- Contributed by Ryan Dunbar

Photo source:

Literature cited:

Brown, J.L. 1974. Alternate routes to sociality in jays - with a theory for the evolution of altruism and communal breeding. American Zoologist 14:63-80.

Brown, J.L., E.R. Brown, S.D. Brown, & D.D. Dow. 1982. Helpers: effects of experimental removal on reproductive success. Science 215:421-422.

Christman, B.J. and G. Steven. 1998. Unambiguous evidence of helping at the nest in Bridled Titmice. Wilson Bull. 110: 567-569.

Emlen, S.T. 1981. Altruism, kinship, and reciprocity in the White-fronted Bee-eater. Pp. 217-230 in Natural Selection and Social Behavior (R. D. Alexander and D. Tinkle, eds). Chiron Press.

Emlen, S.T. 1982. The evolution of helping. I. An ecological constraints model. American Naturalist 119:29-39.

Koenig, W.D. 1981. Reproductive success, group size, and the evolution of cooperative breeding in the Acorn Woodpecker. Am. Nat. 117:421-443.

Moehlman, P.D. 1979. Jackal helpers and pup survival. Nature 277:382-383.

Rood, J.P. 1980. Mating relationships and breeding suppression in Dwarf Mongoose. Anim. Behav. 28:143-150.

Trobino, T. 1999. Helping behavior within sapsuckers (Sphyrapicus spp.). Wilson Bull. 112: 273-275.

Vehrencamp, S.L. 1978. The adaptive significance of communal nesting in Groove-billed Anis (Crotophaga sulcirostris). Behav. Ecol. Sociobiol. 41:1-33.

Werdenich, D. and L. Huber. 2002. Social factors determine cooperation in marmosets. Animal Behaviour 64:771-781.

Woolfenden, G.E. and J.W. Fitzpatrick. 1984. The Florida Scrub Jay: demography of a cooperative-breeding bird. Princeton Univ. Press, Princeton, NJ.

Useful links:

Cooperative Breeding

Cooperative breeding in birds: a comparative test of the life history hypothesis

Evolution of Cooperation

Study Shows the Queen of Beasts Breeds Democratically

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