Local Reproductive Success Research Articles

Attendance off breeders and prospectors reflects the quality off colonies in the Kittiwake Rissa tridactyla

Attendance of breeders and prospectors (prebreeders, failed breeders and non‐breeding adults) was studied from the time of hatching to the end of the breeding season in parts of two neighbouring Kittiwake Rissa tridactyla colonies in Brittany (France). Many clutches in one subcolony had been predated by a Carrion Crow Corvus corone, leading to a lower breeding success. Attendance of breeders and prospecting activity were greater in the more successful colony, and the number of breeding pairs increased in the following year in this colony only. Local reproductive success and social behaviour contributed to the attraction exerted by a colony. The demographic trend was explained by a performance‐based conspecific attraction mechanism, acting through the effect of local reproductive success on recruitment, non‐breeding and fidelity. Study of breeding success and prospecting activity allowed both evaluation of the quality of a colony and prediction of local demographic trends for the following year.

Evaluation of Waterfowl Conservation under the North American Waterfowl Management Plan

In 1986, the North American Waterfowl Management Plan (Plan) was signed by the U.S. Secretary of the Interior and the Canadian Minister of the Environment, with a goal of restoring waterfowl populations to levels of the 1970s via habitat conservation. Central to the Plan is a set of ambitious continental population goals and habitat objectives to be met through broad-based public-private partnerships. Inadequate attention has been paid to evaluation of the Plan, despite the fact that Plan delivery can be enhanced via improved understanding of the effects of habitat conservation on waterfowl population dynamics. Several factors confound the effort to evaluate the Plan at regional and continental levels, including difficulties in accounting for national land-use policies. To date, evaluation has proceeded along 2 avenues of investigation: (1) the study of conservation actions at local-regional levels, and (2) statistical assessment of Plan assumptions. Among other things, results thus far indicate duck production from the U.S. Northern Great Plains has increased in recent years, and intensive treatments such as planted cover have had positive effects on local reproductive success. Many duck species currently exceed Plan population goals; however, population levels of some species, most notably northern pintail (Anas acuta), remain below expectations based on historic relationships with precipitation Management implications include the need for ongoing and more carefully prioritized conservation efforts, broader partnerships, and improved understanding of the linkages between habitats and biological processes. Delivery of the Plan must involve collaboration among the Continental Evaluation Team, joint venture partners, the Adaptive Management and Assessment Team of the U.S. Fish and Wildlife Service, and other conservation groups. Although the challenges and projected costs of Plan conservation efforts are considerable, the long-term potential benefits to waterfowl conservation are great.

CONSPECIFIC REPRODUCTIVE SUCCESS AND BREEDING HABITAT SELECTION: IMPLICATIONS FOR THE STUDY OF COLONIALITY

Habitat selection is a crucial process in the life cycle of animals because it can affect most components of fitness. It has been proposed that some animals cue on the reproductive success of conspecifics to select breeding habitats. We tested this hypothesis with demographic and behavioral data from a 17-yr study of the Black-legged Kittiwake (Rissa tridactyla), a cliff-nesting seabird. As the hypothesis assumes, the Black-legged Kittiwake nesting environment was patchy, and the relative quality of the different patches (i.e., breeding cliffs) varied in time. The average reproductive success of the breeders of a given cliff was predictable from one year to the next, but this predictability faded after several years. The dynamic nature of cliff quality in the long term is partly explained by the autocorrelation of the prevalence of an ectoparasite that influences reproductive success. As predicted by the performance-based conspecific attraction hypothesis, the reproductive success of current breeders on a given cliff was predictive of the reproductive success of new recruits on the cliff in the following year. Breeders tended to recruit to the previous year’s most productive cliffs and to emigrate from the least productive ones. Consequently, the dynamics of breeder numbers on the cliffs were explained by local reproductive success on a year-to-year basis. Because, on average, young Black-legged Kittiwakes first breed when 4 yr old, such a relationship probably results from individual choices based on the assessment of previous-year local quality. When breeders changed breeding cliffs between years, they selected cliffs of per capita higher reproductive success. Furthermore, after accounting for the potential effects of age and sex as well as between-year variations, the effect of individual breeding performance on breeding dispersal was strongly influenced by the average reproductive success of other breeders on the same cliff. Individual breeding performance did not appear to influence the probability of dispersing for birds breeding on cliffs with high local reproductive success, whereas individual breeding performance did have a strong effect on dispersal for birds that bred on cliffs with lower local reproductive success. This suggests that the reproductive success of locally breeding conspecifics may be sufficient to override an individual’s own breeding experience when deciding whether to emigrate. These results, which are supported by behavioral observations of the role of prospecting in recruitment, suggest that both first breeders and adults rely on the reproductive success of conspecifics as “public information” to assess their own chances of breeding successfully in a given patch and to make settling decisions. A corollary prediction is that individuals should attempt to breed near successful conspecifics (a form of social attraction) in order to benefit from the same favorable local environmental conditions. Such a performance-based conspecific attraction mechanism can thus lead to an aggregative distribution of nests and may have played a role in the evolution of coloniality.

Conspecific Reproductive Success and Breeding Habitat Selection: Implications for the Study of Coloniality

Habitat selection is a crucial process in the life cycle of animals because it can affect most components of fitness. It has been proposed that some animals cue on the reproductive success of conspecifics to select breeding habitats. We tested this hypothesis with demographic and behavioral data from a 17-yr study of the Black-legged Kittiwake (Rissa tridactyla), a cliff-nesting seabird. As the hypothesis assumes, the Black-legged Kittiwake nesting environment was patchy, and the relative quality of the different patches (i.e., breeding cliffs) varied in time. The average reproductive success of the breeders of a given cliff was predictable from one year to the next, but this predictability faded after several years. The dynamic nature of cliff quality in the long term is partly explained by the autocorrelation of the prevalence of an ectoparasite that influences reproductive success. As predicted by the performance-based conspecific attraction hypothesis, the reproductive success of current breeders on a given cliff was predictive of the reproductive success of new recruits on the cliff in the following year. Breeders tended to recruit to the previous year’s most productive cliffs and to emigrate from the least productive ones. Consequently, the dynamics of breeder numbers on the cliffs were explained by local reproductive success on a year-to-year basis. Because, on average, young Black-legged Kittiwakes first breed when 4 yr old, such a relationship probably results from individual choices based on the assessment of previous-year local quality. When breeders changed breeding cliffs between years, they selected cliffs of per capita higher reproductive success. Furthermore, after accounting for the potential effects of age and sex as well as between-year variations, the effect of individual breeding performance on breeding dispersal was strongly influenced by the average reproductive success of other breeders on the same cliff. Individual breeding performance did not appear to influence the probability of dispersing for birds breeding on cliffs with high local reproductive success, whereas individual breeding performance did have a strong effect on dispersal for birds that bred on cliffs with lower local reproductive success. This suggests that the reproductive success of locally breeding conspecifics may be sufficient to override an individual’s own breeding experience when deciding whether to emigrate. These results, which are supported by behavioral observations of the role of prospecting in recruitment, suggest that both first breeders and adults rely on the reproductive success of conspecifics as “public information” to assess their own chances of breeding successfully in a given patch and to make settling decisions. A corollary prediction is that individuals should attempt to breed near successful conspecifics (a form of social attraction) in order to benefit from the same favorable local environmental conditions. Such a performance-based conspecific attraction mechanism can thus lead to an aggregative distribution of nests and may have played a role in the evolution of coloniality.

The evolution of coloniality: does commodity selection explain it all? Reply to Tella, Hiraldo and Donázar

We are pleased with Tella et al.'s comment that `commodity selection' offers a promising new approach for understanding some unresolved aspects of coloniality. Our review implies that animals may not be selected to breed colonially, but rather to choose commodities like breeding habitats and mates, which secondarily may have produced breeding aggregations. Tella et al.'s main argument is that commodity selection is a complement to the orthodox economic approach of measuring costs and benefits of high density breeding, rather than a substitute for it.Our general response is to reiterate that the economic approach has failed to provide a general explanation of colony evolution, largely because the wrong questions have been asked. Indeed, when investigating the evolution of coloniality, we do not want to know whether it is better for an individual to breed in a bigger or smaller colony, but we want to understand the processes (rather than the benefits) that lead to breeding aggregations.The estimation of the lifetime reproductive success (LRS) of individuals in a variety of colony sizes may produce information on colonial breeding[1xSee all References[1], but this method cannot reveal the mechanisms of colony formation. If, for example, certain individuals choose small colonies that subsequently expand around them (both in the current and next seasons), then knowledge of their LRS in relation to their `choice' colony size will not elucidate the processes of colony formation. Furthermore, LRS is unlikely to be the right measure of fitness, particularly in this context[2xDanchin, E, Gonzales-Davila, G, and Lebreton, J.D. J. Av. Biol. 1995; 26: 67–75CrossrefSee all References[2].Our main point about reproductive success (RS) is that it is a cue that conspecifics can appraise to aid them in selecting breeding habitats and mates. Their ultimate and proximate processes meet: patterns of spatiotemporal variability of the environment (including the distribution of mates of heterogeneous quality) may have led to the evolution of habitat selection strategies that produce dynamic aggregations of breeding individuals[3xBoulinier, T and Danchin, E. Evol. Ecol. 1997; 11: 505–517CrossrefSee all References[3]. Individuals that prospect for a breeding site for the next season may not need to know the actual causes of local reproductive failure or success (predation, etc.) this season. They only require information on the breeding performance of local breeders in a given year.The discussion on predation underlines a classic problem when studying adaptation: current impact may be misleading, and a comparative study of coloniality showed that coloniality is positively associated with exposure of nests to predation[4xSee all References[4]. But, the high current levels of predation cannot be used to argue that predation played a role in the evolution of coloniality. It may well be that some advantages of coloniality secondarily allowed species to nest in exposed situations[4xSee all References[4]. Similarly, low frequencies of extra-pair paternity in colonial species cannot be used to argue that sexual selection plays a secondary role in the evolution of coloniality. The sexual selection (or `hidden lek') hypothesis[5xSee all References[5]predicts that the frequency of extra-pair copulation is the more direct variable explaining nesting aggregation. In support of this prediction, frequency of extra-pair copulations[6xMoller, A.P and Birkhead, T.R. Am. Nat. 1993; 142: 118–140Crossref | PubMed | Scopus (119)See all References[6]was found to be higher in colonial species.In this context, it is clear that long-term studies are important in allowing to relate the fate of individuals and their breeding distribution to the patterns of spatiotemporal variation of habitat quality, and of factors affecting it (e.g. Ref. [7xSee all References[7]). Experimental approaches are nevertheless necessary to demonstrate causality. The commodity selection framework prescribes the design of much-needed experiments to test predictions of habitat and mate selection in relation to aggregation (e.g. Refs [3xBoulinier, T and Danchin, E. Evol. Ecol. 1997; 11: 505–517CrossrefSee all References, 7xSee all References], Table 1 in Ref. [8xDanchin, E and Wagner, R.H. Trends Ecol. Evol. 1997; 12: 342–347Abstract | Full Text PDF | PubMed | Scopus (241)See all References[8]).

Timing of Prospecting and the Value of Information in a Colonial Breeding Bird

We investigated if one category of birds, prospectors, i.e. those likely to seek future breeding sites, attempt to gather information on the local reproductive success of their conspecifics. If prospecting is an important information-gathering process, it should occur when reliable estimation of the local reproductive success can be made. We tested this prediction in a colonial seabird, the Kittiwake Rissa tridactyla, by monitoring the number of prospectors and the value of the information available on local reproductive success in a series of breeding cliffs during two breeding seasons. We found that the bulk of prospecting occurred when the best information on local reproductive success was available. The pattern was very similar in the two study years (1985 and 1992); prospecting occurred late in the season, as reported for most bird species. This result is consistent with the potential use of conspecific reproductive success as a proximate cue for habitat selection.

Population trends in Kittiwake Rissa tridactyla colonies in relation to tick infestation

Parasite and disease transmission has long been considered one of the main costs of group living, but there is still little empirical evidence. Most seabird species breed in dense colonies and occupy the same breeding sites for many years and thus could be exposed to deleterious levels of haematophagous ectoparasite infestations. The aims of this study were to provide information on the epidemiology of the tickIxodes uriaeand to investigate the relationship between KittiwakeRissa tridactylacolony population trends and local levels of tick infestation in chicks. It is based on a cross‐sectional survey of a large sample of British Kittiwake colonies (22 colonies more than 30 years old and situated on natural cliffs).Ixodes uriaewas by far the most common ectoparasite detected and was found in all colonies examined. Ticks were aggregated between nests, but not between siblings. Very young and old chicks were far less parasitized than chicks of intermediate age and were excluded from the analysis. Among colonies for which we had good data on population trends in Kittiwakes, those decreasing in number had a higher prevalence and density of ticks than those which were increasing. We suggest that this correlation reveals a cause‐and‐effect relationship. By influencing the local reproductive success, ectoparasites can affect the recruitment of new breeders and the breeders' site fidelity in the following year, thus influencing the local trend of numbers. This causal link highlights the potential effect of parasites on their host population and thus needs to be investigated further.

Female Choice in Humans: A Conditional Mate Selection Strategy of the Krummhörn Women (Germany, 1720–1874)

AbstractThe suitors' ownership of land influenced the marriage age of the women in the Krummhörn population (Germany, 1720–1874). This led to a characteristic distribution of the categories of land ownership of husbands by the wife's age at marriage: the younger the brides, the higher was the percentage of high‐status males among their bridegrooms. But the natal status of brides did not exert any significant influence on their age at marriage. Moreover, socially hypergamous women married younger than those whose marriage meant a social drop. We have interpreted these findings as the expression of a conditional female choice strategy with age‐dependent decrease in demands on a marriage partner: “If you are young, be very choosy and marry only a high‐quality mate; the older you become, the more you must reduce your initial standards!” On the average this strategy was adaptive, because in this population land ownership correlated with the local reproductive success of a family.

Fish habitat association in an Ozark stream

Associations of fishes in physically distinct habitats (riffles, inlets and pools) of Flint Creek were studied to evaluate critically the habitat-guild concept — the notion that fishes associate with patches of stream habitat in discrete groups. There was little evidence of significant interspecific association at the habitat level. Most fishes were very generalized in their habitat-use patterns. Faunal similarity between habitats was unrelated to physical-habitat similarity. Assemblages from physically distinct habitats were little different from those from physically similar habitats. The structure of the associations (constancy within groups of commonly occurring species) varied seasonally and from site to site. There were constant associations in pools from summer through fall and this coincided with conditions of high fish density and low food availability, suggesting that the pattern resulted from past or present interaction between species. However, the timing also coincided with recruitment of young. Pools were the favored habitats of young-of-year fishes which dominated assemblages in these areas during summer and fall months. This apparently adaptive pattern of habitat association, operating in tandem with local reproductive success could have been responsible for the constancy observed in pools. Most of the species considered here made use of a variety of habitat conditions over the course of their life histories. Individual patches of habitat satisfied the needs of few fish, and thus, seemed too small a scale for the study of community-assembly mechanisms. There was better evidence of interspecies association at the scale of two or more of these habitat areas combined.

Sources, Sinks, and Population Regulation

Animal and plant populations often occupy a variety of local areas and may experience different local birth and death rates in different areas. When this occurs, reproductive surpluses from productive source habitats may maintain populations in sink habitats, where local reproductive success fails to keep pace with local mortality. For animals with active habitat selection, an equilibrium with both source and sink habitats occupied can be both ecologically and evolutionarily stable. If the surplus population of the source is large and the per capita deficit in the sink is small, only a small fraction of the total population will occur in areas where local reproduction is sufficient to compensate for local mortality. In this sense, the realized niche may be larger than the fundamental niche. Consequently, the particular species assemblage occupying any local study site may consist of a mixture of source and sink populations and may be as much or more influenced by the type and proximity of other habitats a...

RESOURCE ALLOCATION AND REPRODUCTION IN POPULATIONS OF AMPHICARPUM PURSHII (GRAMINEAE)

Five New Jersey populations of Amphicarpum purshii (an annual panicoid grass) were investigated as to total allocation of biomass to reproduction and its distribution between aerial chasmogamous and subterranean cleistogamous inflorescences. Germination of both types of seed was documented, for the first time, in not only the field but under three laboratory temperature regimes. Overall, approximately 29 % of the shoot biomass was allocated to reproduction. On a population basis, subterranean inflorescences accounted for 37–100 % of the reproductive biomass, and these seed (5 × heavier but fewer in number) were the source of most surviving seedlings. Subterranean spikelets contained caryopses significantly more frequently than aerial spikelets. The ratio of the number of viable aerial seed to the number of viable subterranean seed increased from 0/4 to 4/2 with recentness and/or frequency of disturbance. As a pioneer species in secondary succession, Amphicarpum purshii produces a larger subterranean propagule, with greater seedling vigor and a higher probability of local reproductive success, and also a smaller aerial propagule in larger numbers with potentially greater genetic variability.