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The Evolution of Delayed Dispersal in Cooperative Breeders
The delayed-dispersal threshold model is proposed as a guide for organizing and evaluating the ecological factors potentially responsible for this phenomenon and it is concluded that no one factor by itself causes delayed dispersal and cooperative breeding.
Life and Death in the Fast Lane: Demographic Consequences of Road Mortality in the Florida Scrub‐Jay
Abstract: We examined the demographic consequences of road mortality in the cooperatively breeding Florida Scrub‐Jay (Aphelocoma coerulescens), a threatened species restricted to the oak scrub of
Reproductive endocrinology and mechanisms of breeding inhibition in cooperatively breeding Florida Scrub Jays Aphelocoma C. coerulescens)
The absence of high levels of corticosterone in nonbreeders suggests that this reproductive inhibition is not due to glucocorticoid-mediated stress imposed by dominant breeders, and suggests these individuals are reproductively incompetent.
Acorn Production by Oaks in Central Coastal California: Variation within and among Years
Observations did not support the hypotheses that production patterns track resource availability or that they have evolved to attract seed dispersers, but they are generally consistent with two additional hypotheses that masting in these wind-pollinated species evolved because of a proportional increase in fertilization and seed set during mast years.
Prolactin and helping behaviour in the cooperatively breeding Florida scrub-jay, Aphelocoma c. coerulescens
Prolactin levels were significantly correlated with the number of visits to the nest, as well as the amount of food delivered to the young, lending further support to the hypothesis that helping behaviours are mediated by prolactin.
Estimating acorn crops using visual surveys
We describe a visual survey technique for evaluating acorn production. In contrast with previously proposed methods, our technique yields ratio-level data on annual productivity that are analyzable
Delayed breeding in the cooperatively breeding Florida scrub-jay (Aphelocoma coerulescens): inhibition or the absence of stimulation?
The T, LH and GnRH challenge data indicate that nonbreeder males have functional hypothalamo-pituitary-gonadal (HPG) axes, and suggests that inbreeding avoidance may not be the primary factor leading to delayed breeding in females.
Reproductive competition in the communal acorn woodpecker: sisters destroy each other's eggs
An extreme example of reproductive interference between close relatives in the acorn woodpecker is reported, in which communally nesting sibling females in this species destroy their sister's eggs prior to laying their own.
Do helpers increase reproductive success?
  • R. Mumme
  • Biology
    Behavioral Ecology and Sociobiology
  • 1 November 1992
It is concluded that nonbreeders increase their indirect fitness by serving as helpers and that helping behavior in the Florida scrub jay is a trait that has current selective utility.