Breeding success and traits of equal and unequal pairs of little penguins (Eudyptula minor) on Phillip Island during 2001-2008

According to life-history theory, individuals optimize their decisions in order to maximize their fitness. This raises a conflict between parents, which need to cooperate to ensure the propagation of their genes but at the same time need to minimize the associated costs. Trading-off between benefits and costs of a reproduction is one of the major forces driving demographic trends and has shaped several different parental care strategies. Using little penguins (Eudyptula minor) as a model, we investigated whether individuals of a pair provide equal parental effort when raising offspring and whether their behavior was consistent over 8 years of contrasting resource availability. Using an automated identification system, we found that 72% of little penguin pairs exhibited unforced (i.e., that did not result from desertion of 1 parent) unequal partnership through the postguard stage. This proportion was lower in favorable years. Although being an equal pair appeared to be a better strategy, it was nonetheless the least often observed. Individuals that contributed less than their partner were not less experienced (measured by age), and gender did not explain differences between partners. Furthermore, birds that contributed little or that contributed a lot tended to be consistent in their level of contribution across years. We suggest that unequal effort during breeding may reflect differences in individual quality, and we encourage future studies on parental care to consider this consistent low and high contributor behavior when investigating differences in pair investment into its offspring. Key words: attendance patterns, individual quality, meal size, parental care, reproductive costs, seabirds.

Satellite tracking derived insights into migration and foraging strategies of male loggerhead turtles in the eastern Atlantic

[EN] In recent years, information about the movements and timing of migration by male sea turtles has begun to be unraveled. Here, we present the first satellite tracking of male loggerhead sea turtles (Caretta caretta) in the eastern Atlantic. Satellite linked transmitters were attached to five adult males, captured in the near shore waters off Boavista, Republic of Cape Verde. This archipelago hosts the single most important breeding site of loggerhead turtles in the eastern Atlantic.

A Triple-Isotope Approach to Predict the Breeding Origins of European Bats

Despite a commitment by the European Union to protect its migratory bat populations, conservation efforts are hindered by a poor understanding of bat migratory strategies and connectivity between breeding and wintering grounds. Traditional methods like mark-recapture are ineffective to study broad-scale bat migratory patterns. Stable hydrogen isotopes (delta D) have been proven useful in establishing spatial migratory connectivity of animal populations. Before applying this tool, the method was calibrated using bat samples of known origin. Here we established the potential of delta D as a robust geographical tracer of breeding origins of European bats by measuring delta D in hair of five sedentary bat species from 45 locations throughout Europe. The delta D of bat hair strongly correlated with well-established spatial isotopic patterns in mean annual precipitation in Europe, and therefore was highly correlated with latitude. We calculated a linear mixed-effects model, with species as random effect, linking delta D of bat hair to precipitation delta D of the areas of hair growth. This model can be used to predict breeding origins of European migrating bats. We used delta C-13 and delta N-15 to discriminate among potential origins of bats, and found that these isotopes can be used as variables to further refine origin predictions. A triple-isotope approach could thereby pinpoint populations or subpopulations that have distinct origins. Our results further corroborated stable isotope analysis as a powerful method to delineate animal migrations in Europe.

Early post-fledgling survival in a fragmented population of a tropical cooperative breeding passerine

During the last years tropical forest has been a target of intense study especially due to its recent big scale destruction. Although a lot still needs to be explored, we start realizing how negative can the impact of our actions be for the ecosystem. Subsequently, the living community have been developing strategies to overcome this problem avoiding bottlenecks or even extinctions. Cooperative breeding (CB) has been recently pointed out as one of those strategies. CB is a breeding system where more than two individuals raise one brood. In most of the cases, extra individuals are offspring that delay their dispersal and independent breeding what allows them to help their parents raising their siblings in the subsequent breeding season. Such behavior is believed to be due, per example, to the lack of mates or breeding territories (ecological constraints hypothesis), a consequence of habitat fragmentation and/or disturbance. From this point, CB is easily promoted by a higher reproductive success of group vs pairs or single individuals. Accordingly, during this thesis I explore the early post-fledging survival of a cooperative breeding passerine, namely the impact of individual/habitat quality in its survival probability during the dependence period of the chicks. Our study species is the Cabanis’s greenbul (Phyllastrephus cabanisi), a medium-sized, brownish passerine, classified within the Pycnonotidae family. It is found over part of Central Africa in countries such as Angola, Democratic Republic of the Congo, Mozambique and Kenya, inhabiting primary and secondary forests, as well as woodland of various types up to 2700m of altitude. Previous studies have concluded that PC is a facultative cooperative breeder. This study was conducted in Taita Hills (TH) at the Eastern Arc Mountains (EAM), a chain of mountains running from Southeast Kenya to the South of Tanzania. TH comprises an area of 430 ha and has been suffering intense deforestation reflecting 98% forest reduction over the last 200 years. Nowadays its forest is divided in fragments and our study was based in 5of those fragments. We access the post-fledging survival through radio-telemetry. The juvenile survey was done through the breeding females in which transmitters were placed with a leg-loop technique. Ptilochronology is consider to be the study of feather growth bars and has been used to study the nutritional state of a bird. This technique considers that the feather growth rate is positively proportional to the individual capability of ingesting food and to the food availability. This technique is therefore used to infer for individual/habitat quality. Survival was lowest during the first 5 days post-fledging representing 53.3%. During the next 15 days, risk of predation decreased with only 14.3% more deceased individuals. This represents a total of only 33% survived individuals in the end of the 50 days. Our results showed yet a significant positive relationship between flock size and post-fledging survival as well as between ptilochronology values and post-fledgling survival. In practice, these imply that on this population, as bigger the flock, as greater the post fledging survival and that good habitat quality or good BF quality, will lead to a higher juvenile survival rate. We believe that CB is therefore an adaptive behaviour to the lack of mates/breeding territory originated from the mass forest destruction and disturbance. Such results confirms the critical importance of habitat quality in the post-fledging survival and, for the first time, demonstrates how flock size influences the living probability of the juveniles and therefore how it impacts the (local) population dynamics of this species. In my opinion, future research should be focus in disentangle individual and habitat quality from each other and verify which relationship exist between them. Such study will allow us to understand which factor has a stronger influence in the post-fledging survival and therefore redirect our studies in that direction. In order to confirm the negative impact of human disturbance and forest fragmentation, it would be of major relevance to compare the reproductive strategies and reproductive success of populations living in intact forests and disturbed patches.

Influence of climate variability and stocking strategies on greenhouse gas emissions (GHGE), production and profit of a northern Queensland beef cattle herd

Previous studies of greenhouse gas emissions (GHGE) from beef production systems in northern Australia have been based on models of ‘steady-state’ herd structures that do not take into account the considerable inter-annual variation in liveweight gain, reproduction and mortality rates that occurs due to seasonal conditions. Nor do they consider the implications of flexible stocking strategies designed to adapt these production systems to the highly variable climate. The aim of the present study was to quantify the variation in total GHGE (t CO2e) and GHGE intensity (t CO2e/t liveweight sold) for the beef industry in northern Australia when variability in these factors was considered. A combined GRASP–Enterprise modelling platform was used to simulate a breeding–finishing beef cattle property in the Burdekin River region of northern Queensland, using historical climate data from 1982–2011. GHGE was calculated using the method of Australian National Greenhouse Gas Inventory. Five different stocking-rate strategies were simulated with fixed stocking strategies at moderate and high rates, and three flexible stocking strategies where the stocking rate was adjusted annually by up to 5%, 10% or 20%, according to pasture available at the end of the growing season. Variation in total annual GHGE was lowest in the ‘fixed moderate’ (~9.5 ha/adult equivalent (AE)) stocking strategy, ranging from 3799 to 4471 t CO2e, and highest in the ‘fixed high’ strategy (~5.9 ha/AE), which ranged from 3771 to 7636 t CO2e. The ‘fixed moderate’ strategy had the least variation in GHGE intensity (15.7–19.4 t CO2e/t liveweight sold), while the ‘flexible 20’ strategy (up to 20% annual change in AE) had the largest range (10.5–40.8 t CO2e/t liveweight sold). Across the five stocking strategies, the ‘fixed moderate’ stocking-rate strategy had the highest simulated perennial grass percentage and pasture growth, highest average rate of liveweight gain (121 kg/steer), highest average branding percentage (74%) and lowest average breeding-cow mortality rate (3.9%), resulting in the lowest average GHGE intensity (16.9 t CO2e/t liveweight sold). The ‘fixed high’ stocking rate strategy (~5.9 ha/AE) performed the poorest in each of these measures, while the three flexible stocking strategies were intermediate. The ‘fixed moderate’ stocking strategy also yielded the highest average gross margin per AE carried and per hectare. These results highlight the importance of considering the influence of climate variability on stocking-rate management strategies and herd performance when estimating GHGE. The results also support a body of previous work that has recommended the adoption of moderate stocking strategies to enhance the profitability and ecological stability of beef production systems in northern Australia.