Microclimate of American crocodile nests in Banco Chinchorro biosphere reserve, Mexico: Effect on incubation length, embryos survival and hatchlings sex

Crocodilians have temperature-dependent sex determination (TSD) in which incubation temperature determines sex of embryo. Global warming is expected to alter hatchling sex ratio, leading to the extinction of small populations. Regional climate influence on crocodile nest microclimate and hatchlings' characteristics is poorly known. Here, microclimate in natural nests of American crocodile (Crocodylus acutus) and its relation with incubation length, hatchling sex and nesting success was studied in Banco Chinchorro Biosphere Reserve (Mexico) from 2007 to 2010. Temperature and relative humidity in different locations within and outside the nests were registered by data loggers. Incident solar radiation above nest was calculated from hemispheric photographs. Incubation length, proportion of hatchling reaching complete development and hatchling sex were determined at hatching. Nest temperatures exhibited a cyclic daily fluctuation due to solar radiation, which is the major heat source for nests. Clutch temperature was relatively stable and its daily amplitude was negatively correlated with clutch depth and size. Rainfall was the major source of clutch temperature decrease. Clutch and metabolic temperatures increased significantly during incubation. A small sample size failed to demonstrate a statistical relationship between length of incubation and mean clutch temperature. Proportion of embryos reaching complete development depended on maximum and minimum clutch temperature, maximum daily amplitude of clutch temperature and maximum decrease in clutch temperature on a period ≤4 day. Results confirmed a Female-Male-Female TSD pattern for C. acutus, with 31 and 32.5 °C as possible pivotal temperatures. Population and hatchling sex ratios were male-biased and fate of crocodiles of Banco Chinchorro could depend on the magnitude of temperature increase in the future.     

Nest preference of laying hens (Gallus gallus domesticus) and their motivation to exert themselves to gain nest access

In connection with the development of a test method for the attractiveness and appropriateness of nests for laying hens, we carried out an investigation by using a preference test and motivation measuring with the help of push doors. Hens were offered two different nest sites either consisting of a tray filled with wood shavings (litter tray) or a wooden nest box plus wood shavings (nest box). Hens were individually housed in pens (2.0 m × 2.0 m) and had free access to the nest sites until they laid their 15th egg. From that day the hens had to overcome a push door to reach the nest sites. Resistance for entrance was also increased stepwise at the door leading to the hens’ nest. The experiment ended when a hen stopped to lay in her usual nest site for four consecutive days (postexperimental period). The behaviour during the last hour before oviposition was video taped at a level of resistance of 3.5, 6.0, 7.5 and 10.0 N.The hens were categorized into nest and litter layers depending on nest choice. All but one hen pushed maximum resistances between 11.5 and 18.0 N with no differences between nest and litter layers. Behaviour did not significantly change with increasing levels of resistance, but there were significant differences between nest and litter layers. Nest layers spent more time nesting than litter layers while the latter showed a strong tendency to more exploring behaviour. For litter layers, more entries through the push door leading to their nest site and more unsuccessful pushes were detected than for nest layers. According to our results, two types of layers could be distinguished whereas the two were equally motivated to access their nest site.     

Nest-moving by the polydomous ant <Emphasis Type="Italic">Cataglyphis iberica</Emphasis>

In this paper we analyze emigration from nests by the polydomous ant Cataglyphis iberica. Social carrying of workers of this species between different nests of the colony is frequent. In Bellaterra (Barcelona, NE Spain), we monitored field emigration of C. iberica by noting for each nest the migratory behavior of C. iberica workers and, when the nests were attacked by another ant species, Camponotus foreli, we noted the number of C. foreli workers involved in the attacks. Emigration of C. iberica from nests was highly variable. We suggest the main factor determining emigration by this species was attack by workers of C. foreli, so emigration from C. iberica nests was much faster when harassment by C. foreli increased. The system of multiple nests of C. iberica enables this species to abandon attacked nests and to reinstall their population in other nests of the same colony. This reduces risk to the colonies because the route between the different nests is well known by transporter workers.     

The value of a tree species (Caryocar brasiliense) for a stingless bee Melipona quadrifasciata quadrifasciata

The expansion of crop lands and increased logging for charcoal production in the Brazilian savannahs (cerrados) has reduced richness and abundance of Meliponini bees. This may be a consequence of limitation in the availability of potential nesting substrate. The role of a cerrado-tree (Caryocar brasiliense) in providing nesting substrate for Melipona quadrifasciata quadrifasciata was evaluated. Tree (p= 0.006) and branch (p= 0.001) diameters, number of suitable branches (n= 513), height of the trees and availability of trees suitable for bee nesting were all important to the conservation of M. quadrifasciata. However, the high availability of nesting substrate did not seem to limit nest density nor cause the clumped pattern of nest distributions found for the study site. Nests (n= 48) were found mainly in individuals of C. brasiliense (n= 46) suggesting an active tree selection. In addition, nests located on the highest branches (mean = 4.6 m, sd = 1 m, n= 46) had lower probability of being extirpated by human honey collectors.     

黄腹角雉的巢址选择

１９９１￣１９９３年，在浙江省乌岩岭自然保护区对黄腹角雉的巢址选择进行了研究。野外工作共发现黄腹角雉巢１５个，其中８０％位于人工柳杉林中，营果树以柳杉为主，占７３．３％。主成分分析表明，影响黄腹角雉巢址选择的主要因素有４种，依次为：营巢树因素（包括营巢树的高度、胸径、巢位高度和巢上方的植被盖度）、地形因素（包括坡向和坡度）、海拔因素和位置因素。     

Effect of biologically active plants used as netst material and the derived benefit to starling nestlings

Summary The European starling Sturnus vulgaris preferentially incorporates fresh sprigs of particular plant species for use as nesting material. Chemicals found in these plants may act to reduce pathogen and ectoparasite populations normally found in nest environments. The present experiments were performed to test this Nest Protection Hypothesis. In the fild, we experimentally determined that wild carrot Daucus carota, a plant species preferred as nest material, effectively reduced the number of hematophagous mites found within nests relative to control nests without green vegetation. Chicks from nests containing wild carrot had higher levels of blood hemoglobin than chicks from control nests. However, there were no differences in weight or feather development. In the laboratory, we found that wild carrot and fleabane, Erigeron philadelphicus, (also preferred by starlings as nest material) substantially reduced the emergence of feeding instars of mites, while garlic mustard, Alliaria officinalis, (commonly available but not preferred) had little effect on the emergence of mites. We infer that preferred plant material may act to inhibit feeding or otherwise delay reproduction of mites, thereby reducing risk of anemia to developing nestlings.     

Laying sequence,diploid males,and nest usurpation in the leafcutter bee,Megachile rotundata (Hymenoptera: Megachilidae)

Variations from the normal female-male sequence of eggs in nests of the leafcutter bee,Megachile rotundata, were examined. Three alternatives were considered: Out-of-sequence males (i) were diploids, (ii) were the result of supersedure of nests or intraspecific brood parasitism, or (iii) were the result of females occasionally laying a male-female sequence. Electrophoretic data provided definitive evidence of diploid males and of multiple females laying in 7 of 18 nests. In the others, the remaining explanation is that females occasionally lay male eggs before female eggs in a nest.     

Dispersion distance of queens from natal sites in the two haplometrotic paper waspsPolistes riparius andP. snelleni (Hymenoptera: Vespidae)

Dispersion capabilities of new queens were studied in the two haplometrotic paper wasps Polistes riparius and P. snelleni. New queens were marked on the nests in the late summer and located in the next spring. Dispersion distances greatly varied among queens: although a large part of recovered queens nested in close proximity to their natal sites, some did disperse over 100–300 m. This suggests that queens' emigration from and immigration into the censused areas occurred to a substantial extent. On the whole, these species exhibited a weaker “philopatric” tendency than those so far studied for dispersion distance, and seem to have the potential for a long-distance dispersion.     

Termination of parental care due to small clutch size in the temperate damselfish,Chromis notata

Synopsis Reproductive behavior of the temperate damselfish, Chromis notata, was investigated on the island of Mukaishima, Japan, almost daily during the breeding season in 1982. Both males and females repeated reproductive cycles many times during the breeding season. Females had a strong tendency to spawn a whole clutch on one nest during a few hours. The average number of eggs which a male gained per reproductive cycle was estimated at 38560 (480–131100 eggs). Males ordinarily cared for eggs until just prior to hatching, but abandoned more than half of the nests with the eggs numbering less than 11568. Contribution 207 from the Mukaishima Marine Biological Station.