Demography of the everglade kite: Implications for population management

Nichols, James D.; Hensler, Gary L.; Sykes, P.W.

doi:10.1016/0304-3800(80)90018-6

Cited by 41 publications

(37 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The youngest was a female that laid a clutch at 10 mo of age. These data are contrary to estimates of 3 yr for age of first reproduction by Sykes (1979) and Nichols et al (1980). (Table 1).…”

Section: Introductioncontrasting

confidence: 84%

Demography, Environmental Uncertainty, and the Evolution of Mate Desertion in the Snail Kite

Beissinger¹

1986

Ecology

View full text Add to dashboard Cite

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.Wiley is collaborating with JSTOR to digitize, preserve and extend access to Ecology Abstract. The Snail Kite (Rostrhamus sociabilis), an endangered hawk, has a unique mating system in Florida (Beissinger and Snyder 1987): when food is abundant, males or females desert their mates at nearly equal frequency (ambisexual mate desertion) in the midst of a nesting cycle. I examined the demographic and environmental constraints selecting for a clutch size that permits one parent to desert, yet optimizes the number of offspring produced by each parent. Demographic studies, conducted from 1979-1983, indicated that kites have (1) a very high nest failure rate (X = 68%) due most often to unstable nest sites and predation, (2) a variable nesting season (5-10 mo/yr), (3) an early age of first reproduction for a bird this size (10 mo), (4) a high degree of iteroparity (double and potentially triple clutching within a season), and (5) unstable populations. Both nesting success and population size were directly related to Everglades water levels and resultant snail densities. Kites responded to large annual changes in food abundance, not by adjusting clutch size but by deserting their mates and presumably attempting to renest.Kite demographic traits appear to be adaptations to or results of an uncertain environment. Based on 67 yr of Everglades water levels, environmental predictability, measured by spectral analysis and Colwell's (1974) index, was low and influenced by water management regimes: (1) water levels were lowered, (2) annual variation in levels increased and annual cycles became stronger, (3) the period length of long-term drought-flood cycles shifted from 10 or more yr toward 5 yr, and (4) levels became a less predictive cue for favorable nesting conditions.A potential evolutionary pathway from biparental care to mate desertion in Snail Kites is proposed. It is unlikely that mate desertion evolved solely from a context of conflict between the sexes, because kite nesting success is so low that it is probably maladaptive for a parent to desert and jeopardize the survival of any of its first brood. Instead, mate desertion behavior probably evolved in response to a smaller average clutch size; this would allow females to be highly iteroparous and avoid the costs of overinvestment, and should be strongly favored in a highly uncertain environment. Analysis of clutches in museum collections suggests that an apparent decline in clutch size may have occurred in Florida during the past century. The potential for ambisexual mate desertion to occur in other vertebrates is examined.

show abstract

Section: Introductioncontrasting

confidence: 84%

Demography, Environmental Uncertainty, and the Evolution of Mate Desertion in the Snail Kite

Beissinger¹

1986

Ecology

View full text Add to dashboard Cite

show abstract

“…In this chapter, we present analyses of available demographic data on the California spotted owl, using life-history and demographic information in an approach similar to that of Mertz (1971), Nichols et al (1980), Noon and Biles (1990), and Thomas et al (1990, appendix L). Our objectives were (1) to characterize the life-history structure of the California spotted owl, (2) to estimate values of the demographic parameters needed to compute rates of population change, (3) to test the sensitivity of the rate of population change to each of the demographic parameters, (4) to infer which parameters may be most influenced by management decisions, and (5) to suggest future research priorities, as indicated by the demographic analyses.…”

Section: Estimates Of Demographic Parameters and Rates Of Population mentioning

confidence: 99%

The California spotted owl: a technical assessment of its current status

Verner¹,

McKelvey²,

Noon³

et al. 1992

140

106

View full text Add to dashboard Cite

“…Studies carried out with different raptor species (e.g. Hiraldo et al 1996;Real and Mañosa 1997) have shown that demographic models, and thus the predictions of population dynamics on which conservation strategies are based, are usually very sensitive to variations in the values of breeding parameters (Grier 1980;Nichols et al 1980). In that sense, estimates of breeding success and productivity are likely to be more meaningful when obtained across areas and years (Steenhof 1987).…”

Section: Introductionmentioning

confidence: 98%

A long-term large-scale study of the breeding biology of the Spanish imperial eagle (Aquila adalberti)

Margalida¹,

González

Sánchez³

et al. 2007

J Ornithol

View full text Add to dashboard Cite

We present data from a 17-year study of the population biology of a growing population of Spanish imperial eagles Aquila adalberti across most of its breeding range. The objective of this study was to analyse the effects of age, supplemental feeding and rabbit haemorrhagic disease (RHD) on several breeding parameters of this population of eagles. Average clutch size was 2.2 eggs per clutch, and the average incubation time was 41.7 days per clutch. Fledging occurred an average of 76.8 days after hatching, the length of the fledgling period was not correlated to clutch size. The annual average percentage of pairs laying eggs was 88%. A significant reduction in the percentage of pairs laying eggs in the period 1992-1994 (from 91 to 81%) coincided with most of the eagles' territories being affected by the rabbit epizootic disease, RHD, which reduced their food supply significantly.Average productivity was 1.23 chicks per monitored territory, average breeding success was 1.40 chicks in a clutch per territory and the average fledging rate was 1.69 chicks per territory with hatching success. The main known causes of breeding failure during incubation were nest collapse and human disturbance. During chick-rearing, total or partial chick losses were mainly caused by siblicide, disease, malnutrition or nest collapse. In 26.2% of the 1372 monitored breeding attempts, at least one of the breeding birds was a subadult (the male in 56.1% of the cases, the female in 15.5% and both sexes in 28.4% of cases). In cases of mixed-aged pairs (n = 205), 70.7% were the result of a substitution, and 29.3% were the result of the forming of a new pair. Egg laying took place significantly earlier and breeding success was higher in territories occupied by adults than in those occupied by subadults. Breeding parameters were higher in high-quality (rabbit-rich) territories than in low-quality (rabbit-poor) territories, but only for those territories occupied by adults. The values obtained in the territories occupied by adults were only significantly higher than in those of the subadults in highquality territories. Age and territory quality thus simultaneously affected reproductive output.

show abstract

Demography of the everglade kite: Implications for population management

Cited by 41 publications

References 23 publications

Demography, Environmental Uncertainty, and the Evolution of Mate Desertion in the Snail Kite

Demography, Environmental Uncertainty, and the Evolution of Mate Desertion in the Snail Kite

The California spotted owl: a technical assessment of its current status

A long-term large-scale study of the breeding biology of the Spanish imperial eagle (Aquila adalberti)

Contact Info

Product

Resources

About