Dhole pack size variation: Assessing the effect of Prey availability and Apex predator

The two mammalian carnivores, puma (Puma concolor) and South American grey fox (Lycalopex griseus) were studied, in a remote area located in the humid temperate forest of the coastal range of southern Chile. A total of six locations were selected in three landscapes: pre-mountain range, mountain range, and coast. The chosen study locations are relevant because they correspond to threatened areas with different levels of human intervention., so they offer the ideal setting for studying how different species of carnivores respond to both human presence and activities. A dataset was collected for 24 months during 2016–2018 through photo-trapping (13 camera traps placed along 50 photo-trap stations). Wes estimated the apparent occurrence and relative abundance index (RAI) of the fauna registered, by means of generalized linear models to contrast those of an apex predator, such as the puma and a sympatric mesopredator, the South American grey fox, across the three landscapes. The ecological variables assessed were the RAI of the other carnivore considered, exotic carnivores such as dogs and cats, human intervention, farmland effect, prey availability, and habitat quality. The primary hypothesis was that the apparent occurrence and RAI of puma and fox would be positively associated with the RAI of prey and livestock and negatively with human intervention. On the other hand, the secondary hypothesis dealt with the interactions between puma and fox faced with different degrees of human intervention. The results showed that the apparent occurrence of the puma was statistically explained by location only, and it was highest at the mountain range. The apparent occurrence of foxes was explained by both puma apparent occurrence and relative integrated anthropization index (INRA), being highest in the pre-mountain range. Concerning the RAI of pumas, high values were yielded by location and fox RAI. For the RAI of foxes, they were location, puma RAI, and INRA. It can be suggested that eucalyptus plantations from the pre-mountain range could offer an adequate habitat for the puma and the fox, but not the coastal range, as the mountain range could be acting as a biological barrier. Due to the nature of the data, it was not possible to detect any relevant effect between the two carnivores’ considered, between their respective preys, or the very abundant presence of dogs.

Download Full-text

Elevated nest predation risk promotes offspring size variation in birds with prolonged parental care.

10.32942/osf.io/h2mpw ◽

2019 ◽

Author(s):

Gretchen F. Wagner ◽

Emeline Mourocq ◽

Michael Griesser

Keyword(s):

Predation Risk ◽

Reproductive Cycle ◽

Perceived Risk ◽

Nest Predation ◽

Bird Species ◽

Size Variation ◽

Egg Laying ◽

Offspring Size ◽

Natural Predation ◽

Risk Spreading

Predation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging.

Download Full-text

Interannual variation in larval abundance and growth in snapper Chrysophrys auratus (Sparidae) is related to prey availability and temperature

Marine Ecology Progress Series ◽

10.3354/meps10388 ◽

2013 ◽

Vol 487 ◽

pp. 151-162 ◽

Cited By ~ 19

Author(s):

HM Murphy ◽

GP Jenkins ◽

PA Hamer ◽

SE Swearer

Keyword(s):

Interannual Variation ◽

Prey Availability ◽

Larval Abundance

Download Full-text

Climate-associated changes in prey availability drive reproductive dynamics of the North Atlantic right whale population

Marine Ecology Progress Series ◽

10.3354/meps11372 ◽

2015 ◽

Vol 535 ◽

pp. 243-258 ◽

Cited By ~ 23

Author(s):

EL Meyer-Gutbrod ◽

CH Greene ◽

PJ Sullivan ◽

AJ Pershing

Keyword(s):

North Atlantic ◽

Prey Availability ◽

North Atlantic Right Whale ◽

Right Whale ◽

The North ◽

The North Atlantic

Download Full-text

High-Temperature Synthesis of CdSe-Based Core/Shell, Core/Shell/Shell, and Core/Graded-Shell Nanoplatelets for Stable and Efficient Narrowband Emitters

10.26434/chemrxiv.8335262 ◽

2019 ◽

Author(s):

Aurelio A. Rossinelli ◽

Henar Rojo ◽

Aniket S. Mule ◽

Marianne Aellen ◽

Ario Cocina ◽

...

Keyword(s):

Quantum Dots ◽

High Temperature ◽

Equilibrium Shape ◽

Size Variation ◽

Crystal Defects ◽

Atomic Scale ◽

Quantum Yields ◽

Core Shell ◽

Compositional Gradient ◽

High Quality

<div>Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, which are well known to improve the performance of quantum dots. <br></div><div>Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.</div>

Download Full-text

Pregnancy Cravings: Visitation at a Food-Provisioning Site is Driven by the Reproductive Status of Bottlenose Dolphins

Tourism in Marine Environments ◽

10.3727/154427320x15943283422072 ◽

2020 ◽

Vol 15 (3) ◽

pp. 237-248

Author(s):

Valeria Senigaglia ◽

Lars Bejder

Keyword(s):

Prey Availability ◽

Southern Oscillation ◽

Bottlenose Dolphins ◽

Reproductive Status ◽

Food Provisioning ◽

Human Interactions ◽

Increase Risk ◽

Lactating Females ◽

Tourism Attractions ◽

Marine Wildlife

Marine wildlife tourism attractions often use food rewards to ensure close-up encounters with freeranging animals. In Bunbury, Western Australia, the Dolphin Discovery Centre (DDC) conducts a foodprovision program where bottlenose dolphins (N = 22; between 2000 and 2018) are offered food rewards to encourage their visitation at a beach in front of the DDC. We used historical records on individual beach visits by adult female dolphins collected by the DDC from 2000 to 2018 to develop generalized mixed effects models (GLMM) to test whether the frequency of beach visitation was influenced by their reproductive status (pregnant, lactating, nonreproductive) or climatic events (El Niño-Southern Oscillation phases) that could affect prey availability. We also quantified the behavioral budget of dolphins during food-provisioning sessions and documented intra- and interspecific aggressive behaviors using individual focal follows collected in 2017–2018. Provisioned females spend most of the time resting within the interaction area (66.3%) and aggressive interactions arise as a consequence of dominance behavior over food access. Visitation rates were most influenced by reproductive status with pregnant and lactating females visiting the provisioning area more frequently (z = 2.085, p = 0.037 and z = 2.437, p = 0.014, respectively). Females that frequently visit the provisioning area expose their dependent calves to regular human interactions at an early age when they are more susceptible to behavioral conditioning. Such experiences could cause the loss of awareness towards humans and promote maladaptive behaviors such as begging that increase risk of entanglement in fishing gear, boat strikes, and propeller injuries.

Download Full-text