Seasonality in foraging behaviour of Constrictotermes cyphergaster (Termitidae, Nasutitermitinae) in the Caatinga of Northeastern Brazil

The foraging activity of Constrictotermes cyphergaster was investigated in the Caatinga of Northeast Brazil. Eight colonies were monitored for seven days, during both dry and wet seasons. Foraging activity occurred in exposed columns at night, generally between 22:00 and 05:00 h. During the wet season, foraging activity was significantly higher, with one bout every 1.6 ± 0.2 days, than the dry season, when foraging bouts were performed every 1.9 ± 0.3 days. Foraging activity throughout the study colonies presented high temporal synchronization. In both seasons, foraging was negatively correlated with air temperature and positively correlated with humidity. The foraging trails were often re-utilized and ranged from 1 to 18.5 meters in length. No difference between seasons in the area potentially utilized by the study colonies was observed. Approximately 51000 individuals participated in the foraging bout during the dry season, whereas some 87000 individuals participated in the foraging bout during the wet season. This corresponds to 43 and 74% of the estimated total nest population for the dry and wet seasons respectively. The average ratio soldiers:workers during foraging was 1:1.2 in the dry season and 1:2 in the wet season. The higher frequency and number of individuals foraging during the wet season in the present study are likely to be a strategy from C. cyphergaster to store energy reserves to be utilized during the dry season. Received 28 November 2005; revised 29 May 2006 and 16 August 2006; accepted 1 September 2006.     

Spatial distribution, size and density of nests of Myrmicaria opaciventris Emery (Formicidae, Myrmicinae)

Summary: We recorded over the course of one year the location of nests of Myrmicaria opaciventris on five sites in the region surrounding Yaoundé (Cameroon). On these sites, the colonies are polydomous and polygynous. The size of the largest colony, which was made up of 27 nests, was evaluated at 216,575 - 24,750 individuals of which 147,230 - 15,336 were workers. The nests are interconnected by trails that the workers dig during the rainy season. They consist of trenches that are slowly closed to form tunnels. Thanks to these tunnels, the workers are sheltered from their predators when going from one nest to another. They also have easy access to food sources far from the nests. We noted a seasonal variation in the location of the nests. It consists of a kind of budding. Depending on the case, the initial nest might survive or end up by being abandoned during the main rainy season or early in the dry season. The spatial distribution of the nests in the field is, in general, random and the density is lower during the dry season (from 6.2 to 26.4 nests/ha) than during the rainy season (from 12.1 to 50 nests/ha).     

Colony Populations and Biomass in Nests of the Amazonian Forest Termite Anoplotermes banksi Emerson (Isoptera: Termitidae)

The arboreal nests of the termite Anoplotermes banksi are abundant in Central Amazonian primary rain forests. Colony size of 7 nests (weight 92–6891 g) varied between 2,593 and 39,256 individuals/nest (1.5 – 22.1 g termites/nest). Average body fresh weight was 0.9 mg for workers and 2.1 mg for alates. Queens weighed 10–30 mg. No relationship between nest weight and maturity was detected, as the ratio of workers to larvae was 1:1, independent of nest size, and alates were found in nests weighing less than 200 g. Nests of A. banksi (12–18 ha -1) accounted for 12–15% of the nest density of all Isopteran species, but the calculated fresh weight of the termites of this species (15–23 mg/m 2) represented only 0.2–0.4% of the total termite biomass in the study area.     

Testing the importance of nest concealment: does timing matter?

ABSTRACT.   Nest concealment by vegetation is considered an important factor affecting predation rates for many passerines and, therefore, is frequently measured in studies examining nest predation. However, the time when concealment measurements are made may affect the results of such studies, particularly in highly seasonal ecosystems where characteristics of the vegetation later in the breeding period may differ considerably from those at the time of nest-site selection. We used artificial nests baited with quail ( Coturnix sp.) eggs in a highly seasonal tropical dry forest in Jalisco, western Mexico, to test the effects of seasonal change in concealment on nest predation. We placed 40 open-cup, artificial nests in shrubs at the end of the dry season and again at the beginning of the rainy season in 2007, and monitored the fate of the nests and the degree of concealment by vegetation during both periods. Nest concealment was significantly greater during the wet season than during the dry season. The percentage of nests predated was marginally higher during the dry (100%) than the wet (72.5%) season, and daily nest survival was lower during the dry than the wet season. Our results suggest that, in highly seasonal environments such as tropical dry forests, delayed measurement of nest concealment after nest completion rather than during nesting may constitute a significant source of error.     

Nesting Behavior of <Emphasis Type="Italic">Gorilla gorilla diehli</Emphasis> at Kagwene Mountain,Cameroon: Implications for Assessing Group Size and Density

We recorded nesting data at 569 fresh night nest sites, comprising 7032 individual nests, of Cross River gorillas inhabiting the Kagwene Mountain in western Cameroon. The mean night nest group size was 12.4. Overall, 55% of night nests were constructed on the ground and 45% in trees. Significantly more arboreal nests were constructed in the wet season (69%), vs. the dry season (19%). Day nest construction was common at Kagwene (n = 260 nest sites, mean nest group size = 5.98) and we encountered significantly more day nest sites in the wet season. Nest site reuse was also common (35%), though not related to season. Our results of nesting habits concur with those from other western gorilla studies, in which rainfall influences arboreal nesting. However, we encountered wet season arboreal nesting, day nest construction, and overall nest site reuse more frequently than reported for other sites. Our observations have considerable implications when estimating group size and density using traditional nest count data. The gorillas at Kagwene inhabit the highest altitudinal range of all Cross River gorilla subpopulations and rainfall is also high; therefore other subpopulations may demonstrate different nesting characteristics. However, one should consider our findings when attempting to estimate Cross River gorilla density at other localities through nest site data.     

Nest thermoregulation in Polybia scutellaris (White) (Hymenoptera: Vespidae)

Polybia scutellaris (White) builds large nests characterized by numerous spiny projections on the surface. In order to determine whether or not the nest temperature is maintained because of homeothermic conditions of the nest individuals or otherwise, we investigated the thermal conditions within the nests built by P. scutellaris. We measured the temperature within active and abandoned nests. The temperature in the active nest was almost stable at 27°C during data collection, whereas the temperature in the abandoned nest varied with changes in ambient temperature. These results suggest that nest temperature was maintained by the thermogenesis of the individuals of the colony. This is the first report of nest incubation caused by thermogenesis of species of Polybia wasps.     

Diurnal and seasonal fluctuations in wood ant (Formica polyctena) nest temperature in two geographically distant populations along a south – north gradient

Temperature changes were recorded continuously in eleven nests of Formica polyctena located in Southern Finland and the Czech Republic. Nest temperatures were recorded in the Czech site from 2003 to 2005 and in Finland during 2004 – 2005. Seasonal changes in nest temperature were very similar in both locations. During summer, the ants maintained a relatively high and constant temperature in their nest in both locations. Summer nest temperatures in Finland were higher than those in Czech during 2004 –2005 but did not differ from those in Czech during 2003– 2004. This indicated that the geographical differences were less important than difference between seasons. Nest temperature peaked in June. During summer, daily temperature fluctuations were significantly lower in Finland than in Czechia probably due to shorter nights in Finland. Apparent differences in daily temperature patterns were found in nests with different moisture in both locations. In dry nests, temperature peaked in the evening and decreased overnight, whereas the apparent increase was delayed to the night in wet nests. The spring increase in temperature in wet nests was much steeper that that in the dry ones when whole spring period is considered. During one day, temperatures fluctuated much more in dry nests than in wet ones. These differences seem to be caused by differences in thermal capacity between dry and wet nests. Received 24 July 2006; revised 19 February 2007; accepted 19 May 2007.     

Individual and group characteristics affecting nest building in sea lamprey (Petromyzon marinus L. 1758)

Nest building relates to reproductive effort, sexual selection, intersexual conflict and cooperation and may be linked to individual phenotype and interindividual interactions. In particular, larger individuals having more energy reserves are expected to build more, larger nests, without having to trade intrasexual competition for cooperative nest building. Capture–mark–recapture and nest survey of sea lamprey (Petromyzon marinus L. 1758) were combined to assess the relationship between individuals and nesting activity on a spawning ground, throughout a breeding season, during which 202 nests were observed and 114 individuals were captured. On average, males and females stayed 8.33 ± 1.02 and 3.57 ± 1.04 days on the spawning ground, visited 2.26 ± 1.72 and 1.67 ± 1.17 nests and encountered 2.33 ± 2.13 mates for males and 2.29 ± 1.32 mates for females, respectively, and the number of mates encountered increased with the number of nests visited. Body size had no effect on the duration of presence on spawning ground, number of nests visited, number of individuals per nest and sex ratio on nest or nest volume. Bigger nests were found at the end of the season and were not necessarily built by more individuals. This work brings insights on the mating system and cooperative nest building in sea lamprey and may inform managers who want to estimate sea lamprey populations via nest surveys.     

Intra-caste size differences between two social forms of the southern yellowjacket, Vespula squamosa (Hymenoptera, Vespidae)

Summary: Changes in intraspecific social organization are of particular interest to sociobiologists, because an understanding of the genetic and ecological determinants of different social forms bears on the origins of sociality and mating isolation. The Southern Yellowjacket, Vespula squamosa (Drury), occurs as both polygyne and single queen nests. This study examined intra-caste size differences between both social forms of nests. Four polygyne and 13 single queen nests were collected from counties in Florida and Georgia. All single queen nests were one season old, whereas polygyne nests were at least 2 years old. The latter had significantly more workers per nest (p < 0.005), but mean values varied by over 50-fold. Workers and gynes from each social form were compared for six measures of body size: weight, wing length, femur length, thorax length, thorax width and head width. Correlation coefficients for pairs of all traits were highest between head width and both measures of thorax size (r > 0.72), whereas the lowest positive correlations were obtained between weight and all other measures of size (r < 0.64). Gynes of both social forms differed significantly in weight (p < 0.001) and thorax length (p < 0.04), whereas workers differed significantly for all six measures of size (p < 0.04 to p < 0.001).     

Colony size,density and distribution of the leaf-cutting ant,Acromyrmex octospinosus (Reich) in cultivated fields

• 1 Fields of citrus, cacao and rubber in Trinidad were surveyed to measure the number and density of nests of Acromyrmex octospinosus. The greatest density (=153 nests/ha) was in an undisturbed field of young cacao; in established crops density ranged from 3–36 nests/ha.
• 2 Mounds of new nests appeared throughout the year, but most often 4–10 months after the main nuptial flights. Nests reached maximum size, with up to 17 holes, about three years after foundation.
• 3 The ratio of workers to brood was between 5 and 9: 1 for most of the year but it increased to 27: 1 as the sexuals developed. A medium-large colony produced 200–300 queens and males/year; the largest single nest contained about 14,000 individuals.
• 4 The average intake of leaf fragments into laboratory nests was 1 fragment/6.5 individuals. It increased to 1 fragment/2.1 individuals when sexuals were present. Foragers collecting from fields of established cacao preferred flowers to leaves.
• 5 In fields with crops planted on cambered beds, nests were concentrated on the dry edges of drains in the dry season, but they were moved to drier ground in the wet season. Nests were aggregated in 13 of the 16 fields examined, the remaining three fields were exceptionally well drained.
• 6 In newly planted cacao an estimated 6—17% of plants were defoliated and destroyed. In established cacao ants collected about 3000 flowers/ha each day. Laboratory data suggest that ants could defoliate about 25 three-year old citrus trees in a year.

     

Orientation and foraging movements in a patchy environment by the ant Serrastruma lujae (formicidae-myrmicinae)

Serrastruma lujae ants individually search for collembolans in the leaf litter of humid tropical forests. During the dry season, collembolans aggregate in wet patches randomly scattered in the dry litter where numerous single workers come hunting from their nest. We simulated this situation in the laboratory, and observed that workers seem to be able to use the humidity gradient direction to efficiently orient themselves towards a wet patch. Once the patch has been reached, they exhibit area-concentrated searching,consisting, in particular, of adopting a high sinuosity and a low speed. After capturing a collembolan, the ants return to their nest along nearly straight paths. This ability may rely on a spatial memory of the nest location by means of a path-integration process. In the absence of prey, however, various behaviours were observed after an unsuccessful search. Comparisons between these data and the results obtained with a homogeneously wet environment simulating the rainy season situation showed that these ants do not simply respond to the humidity level but are also sensitive to the degree of patchiness of their environment. They can therefore be said to be able to adapt suitably to the considerable climatic changes they encounter during the year.     

Nesting biology and nest re-use ofEulaema nigrita (Hymenoptera: Apidae,Euglossini)

Summary The nesting behavior of the euglossine beeEulaema nigrita was observed in the laboratory after being transferred from three nests to observation boxes. Nests were re-used by successive generations with more than one female working in each re-use process. Associated females were always of the same generation. All females that shared a nest foraged for construction materials (mud, excrement and resin) and each constructed, provisioned and oviposited in her own cells. The number of cells constructed by each female ranged from one to 23. Females stayed in the nests for periods ranging from 15 to 59 days during the hot and wet season and from five to 78 days during the cool and dry season. The egg-to-adult period was related to climatic conditions, and in all re-use processes it was longer than the time of residence of the females in the nests. The meloid beetleMeloetyphlus attacephalus was the only nest parasite. Due to the attack method employed by this parasite, the presence of more than one female in the nest did not result in improved nest defense.     

The seasonal pattern and distribution of green turtle (Chelonia mydas) nesting activity on Aldabra Atoll, Indian Ocean

Green turtles nest all year round on Aldabra, but nesting activity was found to be concentrated during the monsoon season (late November-April) rather than the dry season as previously reported. More trial nests and emergences were made during the dry season. This was considered to be the result of difficulties in nesting during this time of the year rather than to more females attempting to nest, because fewer nests were dug during this season. The number of beaches being used by the turtles has apparently increased but no clear reason could be provided for the varying levels of use of different beaches.     

Colony structure and nest characteristics of European wasps, Vespula germanica (F.) (Hymenoptera: Vespidae), in Victoria, Australia

Abstract European wasps, Vespula germanica , are common across southern and south-eastern Australia and have a negative impact upon urban areas, primary industries, and natural ecosystems. Aspects of colony structure and nest characteristics are examined for nests located in the ground and collected from urban and rural sites in Victoria during two summer−autumn field seasons (1996 and 2001). On average, nests were located 28 cm beneath the surface (range 5−58 cm). The average number of combs in the nest and the total area of the nests increased from early February to late May. In addition, the proportion of cells used to produce workers and different life stages (larvae, pupae) also varied throughout the season; being consistent with studies from New Zealand. No differences in colony structure or nest character­istics were detected between urban and rural nests.     

Comparative aspects of the biology of five Auplopus species (Hymenoptera; Pompilidae; Pepsinae) from Brazil

This study was carried out at the Parque Municipal das Araucárias, in the municipality of Guarapuava, state of Paraná, southern Brazil, from December 2001 to December 2004. Sixty nests belonging to five Auplopus species were collected using trap-nests. The nest cells of all species were built with mud and shaped like a barrel or cylinder, mostly in linear arrangement. Differences between species lie in the colour of the mud and the way in which they organize the mud pellets during the construction of the cells. Few vestibular and intercalary cells were built. The number of cells varied according to the species, never surpassing six cells per nest. We observed a great variation between the five species related to sex ratio and the number of generations per year. Some species presented a delayed life cycle with juveniles entering diapause, others presented an additional short life cycle with no diapause.     

THE BREEDING SEASON IN S.W. ECUADOR

The breeding season on the Santa Elena peninsula in S.W. Ecuador is described on the basis of 1761 nests found in the four years 1955 to 1958. The environment and climate are outlined—a cool, dry season from about May to November and a warm, variable wet season from December to April, when alone rain may fall. It is shown that each year the general breeding season is closely correlated with the rainfall. The peak of breeding varies from year to year by at least a month and its length from about six weeks to three and a half months.
Although all species for which there are enough data, are stimulated to breed after important falls of rain, most of those species of small land-birds which are completely resident, attempt to nest before the rain and often continue for some time afterwards. Some specific differences, between seed- and insect-eating finches, seem to be adaptations to food supply and the availability of nest sites and building material. Such evidence as there is suggests that raptors, waders and waterfowl also nest in the wet season (often late), rather than in the dry season. (Unfortunately herons and sea-birds do not nest in the area.)
Annual differences in the amount of breeding by the same species are thought not to be entirely due to differences in weather between years.
It is suggested that the late (August-September) breeding in the Galápagos Islands described by Lack (1950) and the apparent dry-season nesting of raptors, waders and waterfowl there might be found to be linked with variable or abnormally wet weather, if records of rainfall from the islands were available.     

Spatial patterns, temporal variability, and the role of multi-nest colonies in a monogynous Spanish desert ant

Abstract 1. The colonies of the Spanish desert ant Cataglyphis iberica are polydomous. This study describes the temporal and spatial patterns of the polydomy in this species at two different sites, and presents analyses of its role in reducing the attacks of the queen over sexual brood, and in allowing better habitat exploitation.
2. The spatial distribution of nests was clumped while colonies were distributed randomly. Mean nearest neighbour distance ranged from 3.4 to 7.0 m for nests and from 12.3 to 14.1 m for colonies. Distance of foragers searching for food varied among nests: mean values were between 6.1 and 12.6 m.
3. At both sites, the maximum number of nests per colony occurred in summer, during the maximum activity period of the species. Colonies regrouped at the end of this period but overwintered in several nests.
4. Nest renewal in C. iberica colonies was high and showed great temporal variability: nests changed (open, close, re-open) continuously through the activity season and/or among years. The lifetime of up to 55% of nests was only 1–3 months.
5. Polydomy in C. iberica might decrease the interactions between the queen and the sexual brood. In all colonies excavated just before the mating period, the nest containing the queen did not contain any virgin female. Females were in the queenless nests of the colony.
6. The results also suggest that polydomous C. iberica colonies may enhance habitat exploitation because foraging activity per colony increases with nest number. The relationship between total prey input and foraging efficiency and number of nests per colony attains a plateau or even decreases after a certain colony size (four to six nests). This value agrees with the observed mean number of nests per colony in C. iberica .     

Determinants of reproductive success and offspring sex in a turtle with environmental sex determination

Despite the importance of maternal effects in evolution, and knowledge of links among nest site choice, timing of nesting, offspring sex, and reproductive success in animals with environmental sex determination, these attributes have not been rigorously studied in a combined and natural context. To address this need we studied the relationships between three maternal traits (nest site choice, lay date, and nest depth) and two fitness‐related attributes of offspring (hatchling sex and embryonic survival) in the riverine turtle Carettochelys insculpta, a species with temperature‐dependent sex determination, for four years. Predation and flooding were the major sources of embryonic mortality in 191 nests. Embryonic survival was influenced by both lay date and nest site choice: in one year when nesting began later than average, nests laid later and at lower elevations were destroyed by early wet season river rises. In other years early nesting precluded flood mortality. However, turtles did not nest at the highest available elevations, and a field experiment confirmed that turtles were constrained to nest at lower elevations where they could construct a nest chamber. The principal determinant of hatchling sex in 140 nests was lay date, which in turn was apparently related to the magnitude of the previous wet season(s). Clutches laid earlier in the season (a female's first clutch) produced mainly males, while later clutches (her second clutch) yielded mostly females, due to seasonal increases in air temperatures. Accordingly, later nesting produced female‐biased hatchling sex ratios in 1996, while earlier nesting resulted in sex ratios near unity in the other years. However, all‐female nests were more likely to be flooded than mixed‐sex or all‐male nests in years when nesting was late. In conclusion, we found evidence that the position of two maternal trait distributions (elevation of the nest site and lay date), associated with the reproductive strategy of C. insculpta, reflect a combination of natural selection, physical constraints, and phenotypic plasticity. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81 , 1–16.     

The effect of nest moisture on daily temperature regime in the nests of Formica polyctena wood ants

Summary: Relations between nest moisture and daily temperature regime were studied. Two extreme situations were distinguished among the variable patterns of daily temperature regime found. The first one was characterized by increasing temperature during the day and decreasing temperature during the night and was typical for dry nests exposed to sun. The second one was characterized by a lower temperature during the day that increased rapidly during the night. This pattern occurred in moist shaded nests and was less frequent than the first one.¶Patterns of surface nest temperature, which closely correspond with thermal loss, differ between dry and wet nests as well. In dry nests, the temperature decreased during the night on the whole surface in a similar way. In moist nests, the top parts constantly had a high temperature. The average surface temperature during the night was significantly higher in moist than in dry nests, which implies a higher thermal loss in moist nests. Microbial respiration of nest material strongly correlated with nest moisture, which implies a higher microbial heat production in moist nests.¶The results indicated two mechanisms for the maintenance of internal nest temperature. The first one, used in dry nests, is based on a combination of ant metabolic heat production and the isolation properties of a dry nest. The second one, used in moist nests, is based on the metabolic heat production provided by both the ants and the microorganisms in the nest material. These two strategies differ in the pattern of daily temperature fluctuation.     

黄鼬的产仔环境和鼬巢密度调查

长江中下游平原及华北平原是黄鼬(Mustela Sibirica)的主要产区,在黄土高原地区的数量则较为稀少。为了掌握黄鼬对繁殖环境的选择和各地资源状况,达到合理利用黄鼬资源的目的,我们选择长江流域的崇明岛,淮河流域的宿县,黄河流域的衡水县及黄土高原的太原、交城进行调查。调查期间,得到上海市畜产公司、山西省和太原市畜产公司、衡水地区畜产公司及宿县地区畜产站的热情支持。