Conspecific attraction and nest site selection in a nomadic species, the zebra finch

Conspecific nesting density affects many aspects of breeding biology, as well as habitat selection decisions. However, the large variations in breeding density observed in many species are yet to be fully explained. Here, we investigated the settlement patterns in a colonial species with variable breeding density and where resource distribution could be manipulated. The zebra finch, Taeniopygia guttata, is a classic avian model in evolutionary biology but we know surprisingly very little about nest site selection strategies and nesting densities in this species, and in fact, in nomadic species in general. Yet, important determinants of habitat selection strategies, including temporal predictability and breeding synchrony, are likely to be different in nomadic species than in the non-nomadic species studied to date. Here, we manipulated the distribution of nesting sites (by providing nest boxes) and food patches (feeders) to test four non-exclusive habitat selection hypotheses that could lead to nest aggregation: 1) attraction to resources, 2) attraction to breeding conspecifics, and 3) attraction to successful conspecifics and 4) use of private information (i.e. own reproductive success on a site). We found that wild zebra finches used conspecific presence and possibly reproductive success, to make decisions over where to locate their nests, but did not aggregate around water or food within the study areas. Moreover, there was a high degree of inter-individual variation in nesting density preference. We discuss the significance of our results for habitat selection strategy in nomadic species and with respect to the differential selection pressures that individuals breeding at different densities may experience.

O efeito do regime hidrológico do semiárido na composição de espécies durante dominância de cianobactérias em um reservatório tropical

The potentially toxic cyanobacterial blooms in water bodies are spread across the globe, resulting in the loss of water quality and adverse effects on human health. In arid and semiarid regions, the hydrologic regime characterized by an annual cycle of drought and rain, change the volume and the retention time of the reservoir. Such changes affect the limnological characteristics and causing changes in composition and biomass community of cyanobacteria. The reservoir Cruzeta (Zmax = 8.7 m) is a eutrophic water supply source located in the semiarid tropical (Northeast Brazil). Raised the hypothesis that the hydrological regime of semi-arid tropical is a determining factor in the availability of resources in eutrophic water sources, which influences the composition of dominant species of cyanobacteria. The aim of this study was to analyze the changes in biomass and species composition of cyanobacteria for two annual hydrological cycles and evaluate factors drivers. The study was divided into five distinct periods (dry 2010, rain 2011, dry 2011, rain 2012, dry 2012). The dominant group found in all periods was Cyanobacteria (99% of total biomass), which contributed to the low diversity. The filamentous species Cylindrospermopsis raciborskii was present at both points in almost every study. The colonial species Microcystis panniformis and Sphaerocavum brasiliensis dominated only in periods with lower volumes of water. The diatoms contribute more to the biomass during the period of severe drought. The point near the dam (P1) had phytoplankton biomass larger than the point near the tributary (P2). The dominant species of colonial cyanobacteria lasted until the overflow in P1, and P2 this dominance was until the first rains. The redundancy analysis indicated that physical factors such as light availability and water level were the main factors driving the seasonal succession of phytoplankton. The composition of phytoplankton in spring was alternated by species of filamentous cyanobacteria in conditions of poor stability of the water column, such as Cylindrospermopsis raciborskii, and colonial species under conditions of high stability of the water column, such as Microcystis panniformis and Sphaerocavum brasiliensis. The extremes of torrential rains and severe droughts, governed by the hydrological regime of the semi-arid region led to the availability of resources in the watershed, directing the spatial and temporal dynamics of phytoplankton in the reservoir Cruzeta

Influence of habitat on nest location and reproductive output of Montagu’s Harriers breeding in natural vegetation

We examined distribution and breeding success of semi-colonial Montagu’s Harriers (Circus pygargus) in relation to habitat in Castellón province (eastern Spain). Breeding areas used by harriers at a 1-km2 scale were characterised by having intermediate percentages of scrub cover, their nesting habitat, and also had intermediate coverage of herbaceous crops and non-irrigated orchards. Out of all habitat variables considered, only the percentage of herbaceous crops within 500 m from individual nests had a positive and significant effect on breeding output of the species, suggesting that this habitat may be efficiently used by harriers to forage. Breeding output was also related to laying date and number of breeding neighbours within 500 m around nests, with pairs laying later and having a higher number of breeding neighbours showing lower fledged brood sizes. Number of neighbours (but not laying date) was positively related to scrub cover within 500 m and to cover of herbaceous crops within 2,000 m. Conservation actions for Montagu’s Harrier in the study area should be aimed at preserving areas of scrub with nearby presence of herbaceous crops or natural grasslands. However, habitat improvement for semi-colonial species such as Montagu’s Harrier may not result in a change of species distribution area, and good habitat areas may remain unoccupied, as social factors like presence of conspecifics play an important role in breeding area selection for these species.

(Tables 1,2) Site characteristics and phenotypic attributes of King Penguins (Aptenodytes patagonicus) on Possession Island

In colonial species, it is often assumed that locations in the center of the colony are of highest quality and provide highest breeding success. We tested this prediction, known as the "central-periphery model," in a King Penguin colony in the subantarctic Crozet Archipelago. Breeding activity and survival of 150 penguins, fitted with transponder tags, were monitored over an entire breeding season. Among these 150 birds, 50 bred on the slope at the upper periphery of the colony, where the rates of predation and parasitism by ticks were high. Fifty birds bred in the center of the colony, where rates of predation and tick parasitism were low, and 50 bred at the lower end of the colony, where the rate of tick parasitism was low but predation and flooding were important risks. We predicted that the center of the colony should provide the safest breeding place and consequently be characterized by the highest breeding success and be used by the highest-quality individuals. Yet we found that penguins breeding in the center of the colony had the same breeding success as those at both peripheral locations. In addition, penguins breeding on the upper slope had a higher survival rate than penguins breeding at the center or bottom of the slope and were likely of higher quality. Our study does not support the central-periphery model and emphasizes the complexity behind the relationships among breeding site, breeding success, and individual quality.

An integrated assessment of the continued spread and potential impacts of the colonial ascidian, Didemnum sp. A, in U.S. waters

Didemnum sp. A is a colonial ascidian or “sea squirt” of unknown geographic origin. Colonies of Didemnum sp. A were first documented in U.S. waters in 1993 at Damariscotta River, Maine and San Francisco Bay, California. An alarming number of colonies have since been found at several locations in New England and along the West Coast of the contiguous continental United States. Originally believed to be restricted to artificial structures in nearshore habitats, such as ports and marinas, colonies of Didemnum sp. A have also been discovered on a gravel-pavement habitat on Georges Bank at depths of 40-65m. The wide distribution of Didemnum sp. A, the presence of colonies on an important offshore fishing ground, and the negative economic impacts that other species of noninidigenous ascidians have had on aquaculture operations have raised concerns about the potential impacts of Didemnum sp. A. We reviewed the available information on the biology and ecology of Didemnum sp. A and potentially closely related species to examine the environmental and socioeconomic factors that may have influenced the introduction, establishment and spread of Didemnum sp. A in U.S. waters, the potential impacts of this colonial ascidian on other organisms, aquaculture, and marine fisheries, and the possibility that it will spread to other U.S. waters. In addition, we present and discuss potential management objectives for minimizing the impacts and spread of Didemnum sp. A. Concern over the potential for Didemnum sp. A to become invasive stems from ecological traits that it shares with other invasive species, including the ability to overgrow benthic organisms, high reproductive and population growth rates, ability to spread by colony fragmentation, tolerance to a wide range of environmental conditions, apparent scarcity of predators, and the ability to survive in human dominated habitats. At relatively small spatial scales, species of Didemnum and other nonindigenous ascidians have been shown to alter the abundance and composition of benthic assemblages. In addition, the Canadian aquaculture industry has reported that heavy infestations of nonindigenous ascidians result in increased handling and processing costs. Offshore fisheries may also suffer where high densities of Didemnum sp. A may alter the access of commercially important fish species to critical spawning grounds, prey items, and refugia. Because colonial ascidian larvae remain viable for only 12–24hrs, the introduction and spread of Didemnum sp. A across large distances is thought to be predominantly human mediated; hull fouling, aquaculture, and ballast water. Recent studies suggest that colony growth rates decline when temperatures exceed 21 ºC for 7 consecutive days. Similarly, water temperatures above 8 to 10 ºC are necessary for colony growth; however, colonies can survive extended periods of time below this temperature threshold as an unidentified overwintering form. A qualitative analysis of monthly mean nearshore water temperatures suggest that new colonies of Didemnum will continue to be found in the Northeast U.S., California Current, and Gulf of Alaska LMEs. In contrast, water temperatures become less favorable for colony establishment in subarctic, subtropical, and tropical areas to the north and south of Didemnum’s current distribution in cool temperate habitats. We recommend that the Aquatic Nuisance Species Task Force serve as the central management authority to coordinate State and Federal management activities. Five objectives for a Didemnum sp. A management and control program focusing on preventing the spread of Didemnum sp. A to new areas and limiting the impacts of existing populations are discussed. Given the difficulty of eradicating large populations of Didemnum sp. A, developing strategies for limiting the access of Didemnum sp. A to transport vectors and locating newly established colonies are emphasized. (PDF contains 70 pages)

Trends in fish prey capture by common terns following zebra mussel invasion : do terns track fish species abundance? /

The Common Tern (Sterna hirundo) is a ground nesting colonial seabird. Terns rely primarily on small prey fishes which they obtain through plunge diving for their survival as well as the survival of their offspring during the breeding season. The zebra mussel (Dreissena polymorpha) is a small bivalve mollusk that invaded North American waters in the late 1980's. Through its suspension feeding, the zebra mussel has the ability to alter the entire aquatic ecosystem, ultimately leading to a reduction in pelagic organisms including small prey fish. The objective of the study was to determine what (if any) indirect effects the invasion of the zebra mussel has had on fish prey captured by terns. The study took place in two separate two-year periods, 1990-91 and 1995-96 on a concrete breakwall off the north shore of Lake Erie near Port Colborne, Ontario. Daily nest checks revealed clutch initiation dates, egg-laying chronology, hatching success and morphological egg characteristics (length and breadth). Behavioural observations included time each sex spent in attendance with its brood, the frequency of feeding chicks and the prey species composition and size fed to chicks as well as to females (courtship feeding). Egg sizes did not differ between study periods, nor did feeding rates to chicks, suggesting that food was not a limiting resource. Terns spent less time with their broods (more time foraging) in the 1995-96 period. However, they also had significantly larger broods and fledged more offspring. The time of each individual foraging trip decreased, suggesting that fish were easier to obtain in 1995 and 1996. Lastly, kleptoparasitism rates decreased, suggesting that the costs of foraging (time, energy) actually decreased as fewer birds adopted this strategy to compensate for what I assumed to be a lack of available food (fish). The only significant difference between the periods of 1990, 1991 and 1995, 1996 was a change in diet. Terns delivered significantly fewer rainbow smelt and more emerald shiner in 1995 and 1996. However, the average size of fish delivered did not change. Thus, there was little impact on prey captured by Common Terns in Lake Erie since the invasion of the zebra mussel.

Species-specific characteristics and individual variation of the bark call produced by male Australian fur seals (Arctocephalus pusillus doriferus)

Australian fur seals Arctocephalus pusillus doriferus are colonial breeding animals forming dense social groups during the breeding season. During this time, males establish and defend territories through physical conflicts, stereotyped posturing and vocalisations. While vocalisations are suggested to play an important role in male recognition systems, it has received little attention. Recordings of nine adult male Australian fur seals were made during the 2000 and 2001 breeding seasons at Kanowna Island (39° 10’S, 146° 18' E), Bass Strait, Australia. The in-air bark vocalisations of territory-holding males were used to characterise the Bark Call and to determine whether males produce individually distinct calls, which could be used as a basis for vocal recognition. Seventeen frequency and temporal variables were measured from a total of 162 barks from nine individual males. The Bark Series was more reliably classified (83%) to the correct caller compared to the Bark Unit. This was assigned with less certainty (68%), although the classification was still relatively high. Findings from this study indicate that there is sufficient stereotypy within individual calls, and sufficient variation between them, to enable vocal recognition in male Australian fur seals.

Intense predation of non-colonial, ground-nesting bird eggs by corvid and mammalian predators

Context Loss of eggs to predators is a major cause of reproductive failure among birds. It is especially pronounced among ground-nesting birds because their eggs are accessible to a wide range of predators. Few studies document the main causes of clutch fate of ground-nesting birds. Aims The main objective of the present study was to identify the major egg predator of red-capped plovers (Charadrius ruficapillus). We also investigated the effectiveness of the following two primary strategies available to the plovers to avoid egg predation: (1) the placement of clutches under vegetative cover and (2) avoiding predators by nesting outside the peak season of predator occurrence. Methods Remote-sensing cameras were deployed on plover nests to identify egg predators and nests were monitored over four breeding seasons to document reproductive success and fate. An experiment using false clutches with model eggs investigated the influence of nest cover on the risk of egg predation throughout the year. Line-transect surveys were conducted to estimate the abundance of egg predators in and around the wetlands. Key results The little raven (Corvus mellori) was the major egg predator identified in 78.6% of red-capped plover clutches and in 92.4% of false clutches that were camera-monitored. The hatching success of plover eggs was not influenced by nest cover (P≤0.36), but model egg survival in false clutches improved significantly with the presence of nest cover (P≤0.02). The abundance of little ravens increased during the plover breeding season and was highly negatively correlated with false clutch survival (rpearson≤-0.768, P≤0.005). Conclusions Little ravens were the major predator of red-capped plover eggs and their abundance increased significantly during the plover breeding season. Any influence of nest cover on hatching success of eggs may have been masked by the extremely high rate of egg loss associated with the increased little raven abundance during the plover breeding season. Implications The high rate of egg predation is likely to have negative consequences on the local red-capped plover population, suggesting management is warranted. Little raven populations have expanded and, thus, their impact as egg predators needs to be investigated especially on threatened species. Journal compilation

Nesting habits and colonial productivity of Polistes canadensis canadensis (L.) (Hymenoptera-Vespidae) in a Caatinga area, Bahia State Brazil

The paper aims at increasing the knowledge on the ecology of Polistes canadensis canadensis colonies in a Caatinga region. We studied some aspects of P.c. canadensis nesting habitats and colonial productivity. In the environmental conditions studied, this species nests on several types of substrata, particulary on thorny plants and in caves. The colony productivity and the cell reoccupation rate varies from one colony to another. In some colonies, we found cells with one, two and, more rarely, three reoccupations, this is upto four individuals produced in one cell only. The rate of the first reoccupation was 2.88-34.78%, with na average rate of 15.96%. The number of adults produced by the colonies of Flc, canadensis varied from 10 to 576 individuals. Productivity, given by the relationship between the number of born adults and the number of cell existing in the nest, varied from 31.25 to 123.19% and presented an average of 88.50%.

Variação morfofisiológica das castas da vespa enxameante neotropical Polybia (Trichothorax) ignobilis durante sua ontogenia colonial (Hymenoptera, Vespidae, Epiponini)

Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

Aeromonas no processamento de queijos tipos Minas Frescal e Colonial na região Noroeste do Rio Grande do Sul

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Variação morfofisiológica das castas em algumas espécies de vespas enxameantes neotropicais (Vespidae: Epiponini) ao longo do ciclo colonial

Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

The Cuticular Hydrocarbons Profiles in the Colonial Recognition of the Neotropical Eusocial Wasp, Mischocyttarus cassununga (Hymenoptera: Vespidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)