The Florida Scrub-Jay is a monogamous cooperative breeder in which both males and females display extensive structurally based blue plumage. Juveniles of this species exhibit blue tail and wing feathers that they begin growing as nestlings, and some of these feathers are retained throughout their first year. Although the birds appear to be sexually monochromatic, we assessed whether cryptic dichromatism exists in both the magnitude and pattern of coloration in tail feathers of juvenile Florida Scrub-Jays. We then determined whether variation in plumage coloration is associated with nutritional condition during molt. Tails of juvenile male Florida Scrub-Jays exhibit a greater proportion of UV reflectance than those of females. Mass at age 11 days and ptilochronology of the juvenile tail feathers were used as measures of individual nutritional condition during feather growth, and the latter was found to be positively associated with UV chroma. These data demonstrate that Florida Scrub-Jays are sexually dichromatic and suggest that variation in plumage color may be condition dependent, although we cannot rule out alternative explanations. Juvenile plumage coloration, therefore, has the potential to function as a signal of individual quality in both males and females.

Florida scrub-jays, Aphelocoma coerulescens, perform sentinel behavior in which individuals alternate bouts of watchfulness with little overlap. We examined how calls might facilitate sentinel coordination. Small soft calls labeled conversational gutturals were heard more often from sentinels than from foraging birds. Calls occurred infrequently throughout sentinel bouts but were more common later in bouts. The pattern of calling does not match predictions for a 'watchman's song' at regular intervals nor for a signal at the end of a sentinel bout. Thus, our quantitative assessment of calling by sentinels did not find support for either standard hypothesis. Although Florida scrub-jays clearly have information on each other's sentinel behavior, our results suggest that calls provide perhaps a fraction of this information.

We delineate the winter distributions of the five subspecies of Saltmarsh Sharp-tailed (Ammodramus caudacutus) and Nelson's Sharp-tailed (A. nelsoni) sparrows, and comment on patterns of migration. The two subspecies of A. caudacutus (A. c. caudacutus, A. c. diversus) have similar core winter ranges that extend along the Atlantic coast from North Carolina to northeastern Florida. They also occupy two isolated areas within peninsular Florida in Everglades National Park and on the northwest Gulf coast. Migration in A. caudacutus is mainly confined to the coast. The subspecies of A. nelsoni (A. n. nelsoni, A. n. alterus, A. n. subvirgatus) occupy different but overlapping winter ranges. A. n. nelsoni is the most widespread, occurring from North Carolina to Texas. Some birds migrate along the Atlantic coast southwards in fall, and others follow interior routes through the Mississippi River watershed in both fall and spring. We suggest A. n. nelsoni wintering along the Atlantic coast in spring fly directly inland towards their northern breeding areas. Some birds in fall also approach the southeastern coastline directly across the Appalachian Mountains. A. n. alterus mainly winters along the southeastern Atlantic coast to Florida, and in fewer numbers along the Gulf coast at least to Louisiana. Some A. n. alterus may migrate to the Gulf coast directly via inland routes west of the Appalachian Mountains. A. n. subvirgatus has the most limited wintering distribution, from South Carolina to northeast Florida, and is strictly a coastal migrant south of New England. Limited wintering ranges and narrow winter habitat requirements place continental populations of sharp-tailed sparrows at risk.

Florida scrub-jays are cooperative breeders that live in family groups consisting of a breeding pair, often with several non-breeding helpers. Florida scrub-jays cache food by scatter-hoarding items for later consumption. Within family groups, members have the opportunity to observe and pilfer the caches of other members. We observed jays harvesting experimentally provisioned peanuts alone and in the presence of other family members, to determine whether jays modify their food-handling behavior relative to social context. Non-breeding helpers were less likely to cache in the presence of the dominant male breeder than when alone and all jays tended to cache out of sight when observed by another jay. These changes in caching behavior are consistent with cache protection strategies employed by other species. However, the adaptive value of such cache protection within a sedentary cooperatively breeding family group on a year-round territory is unclear.

1. Using data on breeding birds from a 35-year study of Florida scrub-jays Aphelocoma coerulescens (Bosc 1795), we show that survival probabilities are structured by age, birth cohort, and maternal family, but not by sex. Using both accelerated failure time (AFT) and Cox proportional hazard models, the data are best described by models incorporating variation among birth cohorts and greater mortality hazard with increasing age. AFT models using Weibull distributions with the shape parameter > 1 were always the best-fitting models. 2. Shared frailty models allowing for family structure greatly reduce model deviance. The best-fitting models included a term for frailty shared by maternal families. 3. To ask how long a data set must be to reach qualitatively the same conclusions, we repeated the analyses for all possible truncated data sets of 2 years in length or greater. Length of the data set affects the parameter estimates, but not the qualitative conclusions. In all but three of 337 truncated data sets the best-fitting models pointed to same conclusions as the full data set. Shared frailty models appear to be quite robust. 4. The data are not adequate for testing hypotheses as to whether variation in frailty is heritable. 5. Substantial structured heterogeneity for survival exists in this population. Such structured heterogeneity has been shown to have substantial effects in reducing demographic stochasticity.

Sentinel coordination requires that individuals react to the sentinel behavior of others. Previous work showed that Florida scrub-jays are sentinels more often when given supplemental food. Here we measured how birds in pairs reacted when their mates were fed. Scrub-jays were sentinels less when their mates were fed, demonstrating compensation. Indirect evidence suggests that this compensatory decrease in sentinel behavior was smaller than the increase in sentinel behavior by their mates. In addition, males in newly established groups were sentinels less often.

Urbanization has broad and complex effects on ecological systems. Many of these effects are likely to influence nest success of birds, some positively and others negatively, thus complex interactions among effects are likely to exist that influence patterns of success. Nest success of Florida Scrub-Jays did not differ between a suburban and wildland population or across a human density gradient within the suburban population. Nesting success between egg and nestling stages did not differ in the wildland population, but nest success during the egg stage was high and success during the nestling stage low in the suburban population. As a consequence, nest contents survived longer during the nesting cycle in the suburban population than in the wildland population, even though overall rates of nest success did not differ. In the suburbs, nests with eggs were less likely to be deserted and nests with nestlings were more likely to be depredated or more likely for the nestling to starve than in the wildlands. In both habitats, nest success declined throughout the nesting season. Because suburban birds begin nesting earlier than wildland birds, nests are at a more advanced stage when nest failure rates increase. However, temporal differences in nesting are absent for second and third nest attempts, yet suburban nests still fail later in the nesting cycle. This suggests that site- specific differences exist in the predator community or the behavior of birds increasing their vulnerability to predators that affects timing of nest failure.

. We analyzed metal levels in the eggs of the endangered Florida scrub-jay ( Aphelocoma coerulescens ), an extremely sedentary and modestly long-lived passerine bird. Eggs were obtained as part of the long-term study of this species at the Archbold Biological Station, located in south central Florida. Following a brief and usually short dispersal, Florida scrub-jays remain in a permanent territory in their scrub oak habitat, where they feed mainly on insects and acorns. As they are low on the food chain and sedentary, we expected levels of contaminants to be comparatively low and to reflect the local environment. No significant yearly differences existed for any metal between eggs collected in 1997 (n = 11) and 1998 (n = 5). Arithmetic mean metal concentrations (whole egg, dry weight) were low for arsenic (34 ppb), cadmium (25 ppb), mercury (74 ppb), and lead (66 ppb), intermediate for chromium (226 ppb), and higher for selenium (1,470 ppb) and manganese (2,230 ppb). Except for the low mercury value, all these means were within the range of mean values reported for a wide range of nonpasserine species, including those at high trophic levels, but are lower than concentrations associated with abnormalities in birds. The three essential elements (chromium, selenium, and manganese) were approximately normally distributed, whereas arsenic, cadmium, lead, and mercury were highly skewed (arithmetic mean much higher than geometric mean).

Extensive behavioural and pedigree data on a colour-marked population of Florida scrub-jays (Aphelocoma coerulescens) suggested that this cooperatively breeding species is monogamous, with extremely rare exceptions in which males have two mates. We used multi-locus DNA fingerprinting to test these observations by determining genetic parentage. Despite restricted dispersal and high relatedness between behavioural parents and non-breeding members of the group, DNA fingerprints provided sufficient variability to determine parentage unambiguously in almost all cases. We found no evidence of extra-pair fertilisation of females or egg dumping, and confirmed a suspected case of polygyny in which a mother and daughter laid and incubated in the same nest. Our results confirm that detailed behavioural data allow accurate assignment of genetic parentage in this species. In Florida scrub-jays, large territory size may limit opportunities for cuckoldry, and persistent intense competition for limited breeding space may lead to low variance in the quality of established male breeders. These factors would reduce both the opportunity for, and benefits of engaging in extra-pair fertilisations. Delayed dispersal and cooperative breeding in this species have not evolved as avenues for direct reproduction by unpaired individuals.

Prebreeders of the Florida scrub-jay (Aphelocoma coerulescens) are less likely to be found on their natal territories with a same-sex stepparent than with parents or an opposite-sex stepparent. We tested two models that had been proposed to account for this sexual asymmetry. The dominance hypothesis states that stepparents perceive same-sex prebreeders as competitors, primarily for a mate, so behave aggressively toward them. The pair-formation hypothesis states that prebreeders remain home to pair eventually with the opposite-sex stepparent. Predictions from these two models were tested by analyses from a quarter-century of records on a study population at Archbold Biological Station and by new behavioral field observations at the Station. Results clearly rejected the latter and strongly supported the former hypothesis. No prediction from the pair-formation hypothesis was confirmed: no pairing by a prebreeder of either sex has ever occurred with a stepparent; remaining home was equally frequent in age-one males with stepmothers and genetic mothers, and in females with stepfathers and genetic fathers; and the same results were found in age-two prebreeders. By contrast, the data strongly supported the dominance hypothesis. Field data showed higher aggression rates by stepfathers to male prebreeders and stepmothers to female prebreeders than by parents to their same-sex genetic offspring. Fewer age-one males remained home with a stepfather than with the genetic father, and the same was found for age-one females with a stepmother and genetic mother; at age two, the effect occurred only in female prebreeders. The two hypotheses make different predictions about prebreeders with two stepparents versus with both parents, thus providing a critical test. The dominance hypothesis correctly predicted decreased duration at home by age-one males and females; data for age-two females were in the direction of predicted difference but not significant, and, as in other tests, no effect was found for age-two males. We propose that age-two male prebreeders remain home despite elevated aggression from stepfathers because these prebreeders retain the possibility of budding from or inheriting the natal territory.

We tested the hypothesis that animals caching acorns for future food use may preferentially cache acorns high in tannin content. We used a population of Florida scrub-jays (Aphelocoma coerulescens) that cache acorns from four oak species. Tannin activity in acorns was measured by protein precipitating ability (PPA). Logistic regression models accurately predicted frequency of acorn caching among the oak species, using frequency of usable acorns and PPA loss during burial as predictor variables. Among the four oak species, frequency of caching increased with both increasing frequency of undamaged acorns at peak harvest time, and increasing loss of PPA during burial. Other regression models accurately predicted frequency of undamaged acorns for each species, using green acorn PPA and buried acorn PPA as predictor variables. Among the four oak species, frequency of usable acorns tended to increase with increasing green acorn PPA, and decreased with buried acorn PPA. We suggest that a deterrent effect of tannins on insect larvae is responsible for the differences in frequency of acorns usable to jays among oak species, and that jays select acorns for burial by assessing insect damage. Species differences in PPA change during burial probably reinforce this pattern of scrub-jay caching behavior.

Abstract Two New World jays with different lifestyles, the Pinyon Jay (PJ) Gymnorhinus cyanocephalus and the Florida Scrub Jay (FSJ) Aphelocoma coerulescens (see drawing above), form long-term, monogamous breeding partnerships. PJ pairs.live in large flocks of breeders and prebreeders that roam widely over home ranges encompassing thousands of hectares, lack territories, and breed colonially (Marzluff and Balda 1992). FSJ pairs live alone, or with a few prebreeding offspring that act as helpers, in permanent territories, and individuals rarely move more than 1 or 2 km from their natal site during their entire lifetimes (Woolfenden and Fitzpatrick 1984, 1986). We discuss the establishment of long-term, socially monogamous pair bonds, the influence of mate fidelity on reproduction, and the factors that promote mate fidelity in these phylogenetically related, but ecologically dissimilar corvids. Although both species form long-term pair bonds, clear differences exist between many features of these partnerships. We conclude that the disparities result from marked differences in sociality, use of space and use of resources.