Seasonal acoustic behavior of blue whales (Balaenoptera musculus) in the Gulf of California,Mexico

Six years of passive acoustic monitoring data from the Gulf of California reveal seasonality and movements for the northeastern Pacific blue whales. Three sites were studied, one from the southern (Punta Pescadero) and two from the northern (Isla Tiburon and Canal de Ballenas) regions. A total of 4,953 h were analyzed, and 15,539 blue whale calls were detected, of which 2,723 (18%) were A calls, 11,249 were B calls (72%), and 1,567 were D calls (10%). A and B calls were produced both as song units (2,524) or AB singular calls (2,026). The high rate of songs and their seasonality suggest that the GC is a winter‐breeding ground. A shift from AB call predominance in winter, to D calls in spring and early summer, especially at the entrance of the GC, suggests the importance of this area for reproduction and foraging. Analysis of calling frequency suggests a clear movement of blue whales from the southern region (Punta Pescadero) to the northern regions (Canal de Ballenas and Isla Tiburon), with subsequent southern movement in March. The seasonality and mobility of blue whales in the Gulf of California, inferred from their calling, contributes to the ecological understanding of this population.     

Kori bustard (Ardeotis kori struthiunculus) occurrence in the Serengeti grass plains,northern Tanzania

The kori bustard (Ardeotis kori struthiunculus) is indigenous to grasslands and lightly wooded savannahs of southern and eastern Africa. The species is categorized as near threatened in its entire range due to anthropogenic factors and low reproductive rates. The aim of this study was to analyse the impact of grass colour, grass height, season and location on the density/occurrence of this bird species in the Serengeti grass plains, Tanzania. Data were collected from January 2014 to June 2015 using transect counts in four seasons: (i) short dry, (ii) long rain, (iii) long dry and (iv) short rain seasons, respectively. The mean density of kori bustard in the grass plains was 0.25 ± 1.01 per 0.2 km² with near‐significant differences among the study sites. The occurrence of kori bustard was high in the medium height (11–30 cm) during the long rain and short dry seasons. The kori bustard density is relatively low, and the distribution varies with grass height and season. We suggest that conservation efforts should be directed at preventing its local extinction by protecting the habitat from excessive human activities, such as livestock grazing and illegal offtake.     

Possible mechanisms mitigating reproductive interference supposed between Xylena fumosa (Butler) and X. formosa (Butler) (Lepidoptera: Noctuidae: Xyleninae), both by-captured in a commercial pheromone trap for Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae: Heliothinae)

As differences in sex pheromones usually act as a barrier against interspecific mating, the fact that the closely related moths Xylena fumosa (Butler) and X. formosa (Butler) (Lepidoptera: Noctuidae: Xyleninae) are commonly attracted to the sex pheromone lure for Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae: Heliothinae) seems unlikely, suggesting that some mechanisms exist between them to mitigate a potential reproductive interference in pheromone communications. Thus, we examined the overlaps in ecological niches of the two species, and their attractiveness to commercial pheromone lures for other moths, through pheromone trap surveys and published reports. Long-term field surveys using traps baited with five to six types of artificial sex pheromone lures including those designed for H. armigera, and information in published works revealed that there was a nonnegligible overlap between the two species in terms of seasonal timing of captures, geographic habitats and host plants. These factors, therefore, did not appear to provide conclusive evidence mitigating reproductive interference. However, there was a slight but significant difference between them in the trends of attraction to different artificial pheromone lures; X. formosa was attracted albeit in a small number to the lures for Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), whereas X. fumosa was only attracted to those for H. armigera. This suggests that differences in pheromone composition, rather than differences in temporal and spatial distributions, between the two species could play a more significant role in premating reproductive isolations.     

Seasonality regulates the effects of resource addition on plant diversity and ecosystem functioning in semi-arid grassland

季节性调控资源添加对半干旱草原物种多样性与生态系统功能的影响 在资源富集的条件下，物种丰富度、群落地上生产力以及群落稳定性的季节变化通常被忽视。本研究致力于探究在干旱区草原，资源添加如何在生长季的不同月份影响物种丰富度、群落地上生产力及其稳定性。我们在内蒙古草原设置了为期3年的资源添加(氮添加-N、水添加-W以及水、氮共同添加-NW)实验，利用季节性取样的方法，去检验资源添加(水、 氮)对物种丰富度、群落地上生产力及其稳定性的影响，并通过构建结构方程模型分析资源添加调控不同月份与整个生长季群落稳定性的内在机制及其相对重要性。研究结果表明，资源添加在整体上未改变5与6月的群落地上生产力，而氮与水氮共同添加显著提高了7与8月的群落地上生产力。资源添加在整体上未改变物种丰富度、物种异步性与群落稳定性。氮添加与水氮共同添加提高了7与8月的群落地上生产力，主要源于其增加了多年生丛生禾草的地上生产力。结构方程模型分析表明：在生长季前期与整个生长季，物种异步性是决定群落稳定性的主要机制；在生长季后期，多年生丛生禾草的稳定性是驱动群落稳定性的主要因子。我们的研究证明：在半干旱草原，季节与资源的有效性可以交互影响群落地上生产力及其稳定性。这些发现对于半干旱草原的季节性可持续管理具有重要意义，以期减轻土地利用与全球变化带来的影响。     

Plant size and season of burn affect flowering and fruiting of the grasstree Xanthorrhoea preissii

Flowering and fruiting were assessed on 14 populations of the grasstree, Xanthorrhoea preissii Endl., occurring in the Darling Range near Perth, Western Australia. Independent of site, season of burn or year of flowering, there was a strong relationship between plant height, which varied from 0.1 to over 2 m, and the incidence of postfire flowering, which varied from 1% (winter burn) to 75% (summer burn) of grasstrees present. There was no relationship between inflorescence dimensions, or flower or fruit production on a spike basis, and plant size/age (height). When standardized for height, spring‐burnt populations produced 40% as many inflorescences as autumn‐burnt populations and 20% as many as summer‐burnt populations. Inflorescences produced by spring‐burnt plants were moderately smaller than those by summer–autumn‐burnt plants. Fruit density per spike in autumn‐burnt plants was 80% of that in spring–summer‐burnt plants. The net effect was an average of 70 000 fruits produced per 100 summer‐burnt plants, 22 000 in autumn‐burnt plants, and 14 000 in spring‐burnt plants. Ecophysiological explanations of these results and their implications for population dynamics have yet to be explored.     

Predators and the breeding bird: behavioral and reproductive flexibility under the risk of predation

A growing body of work suggests that breeding birds have a significant capacity to assess and respond, over ecological time, to changes in the risk of predation to both themselves and their eggs or nestlings. This review investigates the nature of this flexibility in the face of predation from both behavioural and reproductive perspectives, and also explores several directions for future research. Most available work addresses different aspects of nest predation. A substantial change in breeding location is perhaps the best documented response to nest predation, but such changes are not always observed and not necessarily the best strategy. Changes in nesting microhabitat (to more concealed locations) following predation are known to occur. Surprisingly little work addresses the proactive avoidance of areas with many nest predators, but such avoidance is probably widespread. Individual birds could conceivably adopt anti‐predator strategies based on the nest predators actually present in an area, but such effects have yet to be demonstrated. In fact, the ways in which birds assess the risk of nest predation is unclear. Nest defence in birds has historically received much attention, but little is known about how it interacts with other aspects of decision‐making by parents. Other studies concentrate on predation risk to adults. Some findings suggest that risk to adults themselves influences territory location, especially relative to raptor nests. An almost completely unexplored area concerns the sorts of social protection from predators that might exist during the breeding season. Flocking typical of the non‐breeding season appears unusual while breeding, but a mated pair may sometimes act as a “flock of two”. Opportunistic heterospecific sociality may exist, with heterospecific protector species associations more prevalent than currently appreciated. The dynamics of singing during the breeding season may also respond to variation in predation risk, but empirical research on this subject is limited. Furthermore, a few theoretical and empirical studies suggest that changes in predation risk also influence the behaviour of lekking males. The major influence of predators on avian life histories is undoubtedly expressed at a broad phylogenetic scale, but several studies hint at much flexibility on an ecological time scale. Some species may forgo breeding completely if the risk of nest predation is too high, and a few studies document smaller clutch sizes in response to an increase in nest predation. Recent evidence suggests that a female may produce smaller eggs rather than smaller clutches following an increase in nest predation risk. Such an increase may also influence decisions about intraspecific brood parasitism. There are no clear examples of changes in clutch/egg size with changes in risk experienced by adults, but parental responses to predators have clear consequences for offspring fitness. Changes in risk to adults may also influence body mass changes across the breeding season, although research here is sparse. The topics highlighted herein are all in need more empirical attention, and more experimental field work whenever feasible.     

Spring phenology rather than climate dominates the trends in peak of growing season in the Northern Hemisphere

Shifts in plant phenology regulate ecosystem structure and function, which feeds back to the climate system. However, drivers for the peak of growing season (POS) in seasonal dynamics of terrestrial ecosystems remain unclear. Here, spatial–temporal patterns of POS dynamics were analyzed by solar-induced chlorophyll fluorescence (SIF) and vegetation index in the Northern Hemisphere over the past two decades from 2001 to 2020. Overall, a slow advanced POS was observed in the Northern Hemisphere, while a delayed POS distributed mainly in northeastern North America. Trends of POS were driven by the start of growing season (SOS) rather than pre-POS climate both at hemisphere and biome scale. The effect of SOS on the trends in POS was the strongest in shrublands while the weakest in evergreen broad-leaved forest. These findings highlight the crucial role of biological rhythms rather than climatic factors in exploring seasonal carbon dynamics and global carbon balance.     

Effects of lighting programs on onset of the ovulatory season in mares

Using 240 pony mares, lighting regimens were tested for their efficiency in hastening the onset of the ovulatory season. The mean number of days from January 1 to first ovulation was used as the end point. No advantage was gained by beginning a fixed lighting regimen ($\text{15.5L}\text{8.5D}$, hours light/hours dark) November 1 (66 ±8) versus December 1 (65 ±9), but beginning on January 1 was less efficient (98 ±8; controls, 132 ±5; P<0.05). In another experiment, daily three-hour interruptions of either the light phase (67 ±10) or the dark phase (71 ±11) did not significantly retard the effectiveness of a fixed regimen of $\text{15L}\text{9D}$ (54 ±5; controls, 142 ±6). A $\text{15L}\text{9D}$ regimen every other day (natural day length on alternate days) resulted in an interval (85 ±7) that was shorter (P<0.05) than for the controls and longer (not significant) than for the daily $\text{15L}\text{9D}$ regimen. When used with natural day length, a one-hour pulse of light in the evening (15 hours after sunrise) was not effective (141 ±6); a one-hour pulse in the morning 9.5 hours after sunset) was only partially effective (117 ±6). In another experiment, the interval was reduced (P<0.05) in a group with one hour of light fixed at 4:00 a.m. with natural day length (85 ±8; $\text{15L}\text{9D}$, 75 ±7; controls, 126 ±9). Results indicated that a fixed one-hour pulse of light at 4 a.m., used with natural day length, may provide an acceptable level of stimulation.     

The solar wind and hallucinations--a possible relation due to magnetic disturbances

Data from the 19th century on hallucinations and magnetic disturbances were found to exhibit a direct and statistically significant correlation. The aa magnetic index over the period 1868-89 and concurrent visual hallucinatory activity were found to co-vary (Spearman coefficient = .64; P less than .05). Magnetic influences on the pineal hormone, melatonin, are suggested as a possible source of variation.     

Internal embryonic brooding and development in the southern Australian micro-snail Tricolia rosea (Angas, 1867) (Vetigastropoda: Phasianellidae: Tricoliinae)*

ABSTRACT

Internal embryonic brooding has been suggested as an adaptation to enhance reproductive success in minute gastropods. It is rare in vetigastropods, previously known in only two species of Spectamen Iredale, 1924 (Solariellidae) from South Africa. Herein it is confirmed in the temperate Australian micro-snail Tricolia rosea (Angas, 1867), with up to 46 embryos observed within a gravid female. Embryos are brooded to an advanced stage, possessing a translucent, calcified shell and a calcified operculum. The initial protoconch is colourless, spirally sculptured and delineated by a consistent axial demarcation at the 0.75 whorl mark, when it measures 320?µm across. Beyond this, the second part of the protoconch is tinted pink, the strong spiral sculpture continues but the ribs and interstices are broader, with smoother surface microsculpture. At the 1.1 to 1.125 whorl mark the protoconch measures 400?µm across when transition to smooth teleoconch sculpture occurs. No brooded embryos possessed teleoconch sculpture. The potential relationship of protoconch morphology to embryonic development, hatching, feeding and release are considered. The mechanism of fertilisation is unknown, but embryos in a brood are at the same developmental stage. Unanswered questions in embryonic development and problems with protoconch terminologies in vetigastropods are also discussed.