Rapid increase in Adelie penguin populations in the Lutzow-Holm Bay area since the mid 1990s

The Adelie penguin, Pygoscelis adeliae, an important component of the Antarctic marine ecosystem, is closely associated with sea ice. Ten breeding populations along the Soya Coast of Lutzow-Holm Bay have been monitored since the 1960s by the Japanese Antarctic Research Expedition and shown to be increasing. In most colonies, small peaks of population increase were observed in the late 1980s with a rapid increase from the mid 1990s. Frequent sea ice break-ups in Lutzow-Holm Bay in the mid 1980s and since the late 1990s are thought to have induced the population increase through increased subadult survival and preferred prey availability. Population monitoring therefore needs to be continued carefully in relation to the environmental changes

Are stomach temperature recorders a useful tool for determining feeding activity?

Despite a number of limitations, stomach temperature recorders are still commonly used to determine feeding activity in free-ranging marine predators. In this regard, it is important to improve the detection rate of these systems by, for instance, increasing the probability that a cold prey touches the sensors. In the present study, we compared the detection rates and mass estimations of water and fish prey ingested by captive king penguins using a two-point temperature recorder (STL) and a single, but large, point recorder (SICUP). Prey items were of different masses (5-45 g) and delivered at different frequencies (high vs. low). Ingestions were recorded as precipitous drop followed by an exponential rise (PDER). Overall, 57.9, 56.0 and 70.0% of the ingestions were detected by the SICUP and the upper and lower sensors of the STL, respectively. Our study confirmed that employing two sensors improves the detection of prey ingestion, but the detection of very small prey items remains insufficient and prey items swallowed at short intervals are detected as cumulative ingestion events. Nonetheless, the total mass of food ingested can be estimated with more than 70% confidence

Subjectivity in bio-logging science: do logged data mislead?

Logging of data using animal-attached archival units (bio-logging) involves potential sources of subjectivity that are reviewed in the present paper. Subjectivity may be the result of technical limitations of which the selection of the correct sampling frequency is particularly critical. Mistakes or aberrant data can also result from transitory defaults in the loggers functioning. Similarly, the use of purpose-written software to pre-process logged data before analysis is another step during which substantial modification of the raw data can occur. Apart from technical limitations, bio-logging devices are also known to modify the behaviour of the animal studied. Finally, arbitrary conclusions can eventually be drawn out from the \u27visual\u27 analysis of logged-data. The second part of this review proposes a non-exhaustive list of precautions so as to enhance objectivity in bio-logging approach. Among these precautions, assessment of the impact that data-logger may have on the animal, appropriate calibrations (for example for transformation of the raw measurements into useable variables) and multi-data sampling are useful steps in bio-logging utilization

Diving angle of great cormorants

Seabirds can maximize the relative time spent at depths where prey occur by minimizing the commuting time taken to reach these depths. One way to achieve this goal is to modify dive angle, but there are few measures of dive-angle in free-foraging seabirds. In 2003, we monitored simultaneously the swimming speeds and diving depths of great cormorants (Phalacrocorax carbo) foraging off the Greenland coast, and used these data to reconstruct their descent angle. Both males and females dived on average 12 m. We suggest that birds are able to reduce their descent time for dives beyond this depth by performing pre-dive leaps that allow them to use the momentum of the fall to descend almost vertically and at great speeds. Such pre-dive leaps in shallower dives would be unsuitable because of the proximity of the seabed and the risk of startling prey. Finally, in contrast with deeper divers, descent angles were not steeper when undulations were observed in the depth profile of the previous dive, probably because birds feed on dispersed prey

Efecto de las micro-osteoperforaciones en el movimiento dentario ortodóncico en ratas adultas

Tesis (Cirujano Dentista)Objetivo: Determinar el efecto de MOPs en la aceleración del movimiento dentario ortodóncico en ratas adultas. Materiales y Métodos: Un total de 16 ratas Sprague-Dawley machos adultas de 32 semanas de edad fueron analizados en esta investigación. En cada rata se instalaron aparatos ortodóncicos en el maxilar superior. La fuerza se aplicó por medio de un coil de Nitilol ubicado entre el 1º molar superior e incisivo central superior, utilizando una fuerza de 25 gr. El lado izquierdo fue sometido a MDO + MOPs, la cual fue analizada y comparada con el lado derecho, que fue sometido solo a MDO. Las 16 ratas fueron agrupadas según día de experimentación en días 7, 14, 21 y 28. Resultados: El lado MOP fue el que tuvo mayor movimiento y velocidad las primeras dos semanas, pero a partir del día 21 el lado experimental tuvo una desaceleración, mientras que el lado control tuvo mayor movimiento y velocidad. Ninguno de los cambios fue estadísticamente significativo. Conclusiones: El tratamiento de MOPs es capaz de aumentar la velocidad del MDO en ratas adultas en las tres primeras semanas de aplicar el estímulo, pero no es estadísticamente significativo en períodos cortos de tiempo. Se hace necesaria la intervención periódica de perforaciones para reactivar el Fenómeno Aceleratorio Regional.Objective: To determine the effect of MOPs on the acceleration of orthodontic tooth movement in adult rats. Materials and Methods: A total of 16 Adult Sprague-Dawley rats of 32 weeks of age were analyzed in this investigation. In each rat orthodontic appliances were installed in the upper jaw. The force was applied by means of a coil of Nitilol located between the upper 1 molar and upper central incisor, using a force of 25 gr. The left side was subjected to ODM + MOPs, which was analyzed and compared with the right side, which was only subjected to ODM. The 16 rats were grouped according to day of experimentation on days 7, 14, 21 and 28. Results: The MOP side was the one that had the most movement and speed during the first two weeks, but from day 21 the experimental side had a deceleration, while the control side had more movement and speed. None of the changes was statistically significant. Conclusions: The treatment of MOPs is able to increase the speed of the ODM in adult rats in the first two weeks of applying the stimulus, but it is not statistically significant in short periods of time. Periodic intervention of perforations is necessary to reactivate the Regional Accelerator Phenomenon

Bio-logging science: sensing beyond the boundaries

Bio-logging has emerged as a tool in animal biology much as genomics has emerged as a tool in the study of cellular and organ function. Bio-logging is certain to increase in its importance and to influence the way we study events and processes that are beyond the usual boundaries of perception and that are remote from the observer. It is providing insights into the behaviour and function of organisms in environments that are hostile to the observer and in natural situations. In terms of the way that data are collected it has much in common with remote sensing and Earth observation. This includes post hoc analysis and interpretation of extensive data sets involving a low diversity of measured variables. Owing to the sparseness of data sets, practitioners need to develop better methods of applying the data to models of the organisms being studied. Although increasing technological sophistication is leading to collection of a greater diversity of variables, this also brings complications of interpreting multi-dimension data sets. Although it appears that technology currently constrains the type of biological questions that can be addressed, there is a danger that technological advancement could result in a loss of focus on hypothesis testing. There is evidence that the discipline of bio-logging is developing a substructure within which specialist teams of modellers, theoretical and field biologists, and engineers collaborate to address complex biological questions

Finding the balance: the effect of the position of external devices on little penguins

Many studies on the foraging behaviour of penguins rely on data collected with back-mounted data recorders, which can greatly affect the drag of swimming birds. In recent years, the size of devices has been minimised to reduce drag. In addition, devices have been positioned on the lower back of penguins to reduce the effect of the flow separation caused by the device on the penguinユs body. Nevertheless, a device placed on the lower back of penguins is further away from the centre of gravity which may make balancing and swimming difficult. In this study, we used accelerometers to measure and test quantitatively whether the heaving and surging acceleration (as a measure of imbalance) of penguins swimming through a winding channel was different when an external accelerometer was positioned on the lower back compared to the middle of the back (closer to the centre of gravity).Heaving acceleration was different only for two of the seven penguins when a device was placed on the lower back rather than the middle of the back. While the difference was statistically significant, it was too small (less than 1 m/s2) to indicate a difference in the swimming behaviour. Although surging acceleration was consistently different in all seven penguins, we suspect this measurement indicated differences in acceleration between two parts of the body (tail and middle back) rather than an effect in balance. Overall, it seems that the balance of little penguins is not greatly affect by positioning of a device. Nevertheless, further experiments with free-ranging penguins are needed to evaluate fully whether the positioning of a device can affect balance of a penguin swimming on the water surface or its buoyancy when diving in the water