Climate Change

In our paper, "Climate change impacts on seabirds and marine mammals: The importance of study duration, thermal tolerance and generation time" we conduct a systematic review of seabirds and marine mammals in response to climate change and variability. This assessment includes mapping the global distribution of climate studies on these species, identifying the required study duration to detect climate change impacts, assessing species vulnerability based on thermal ranges and age at first breeding, and providing recommendations for future assessments of climate change impacts on marine vertebrates.

In recent decades, the world's oceans have played a central role in climate regulation, absorbing a significant portion of the extra heat and carbon dioxide generated by the greenhouse effect. This has led to considerable temperature increases in marine systems globally, with potential implications for marine biodiversity. However, the extent and direction of these changes vary across regions, and the underlying natural patterns of climatic variability are complex, making it challenging to attribute biological responses to long-term climate change.

Marine top predators, including seabirds and marine mammals, serve as vital sentinels of ecosystem change due to their long lifespans and large-scale mobility. They integrate information from the entire marine food web, providing valuable signals of climate change through demographic, distributional, behavioural, dietary, and phenological traits. These predators also exert significant top-down effects on marine food webs and ecosystem functioning. With the feasibility of population monitoring, many multi-decadal studies have been conducted, offering insights into the indirect and, in some cases, direct effects of climate on these species.

Quantitative research syntheses on endothermic marine predators are relatively rare, but essential. Seabirds, for example, have shown global-scale responses to climate through demographic, distributional, and phenological shifts, though some responses remain inconsistent. Long-term studies are often deemed necessary to observe biodiversity responses to climate change, and defining temporal thresholds can be challenging, especially in diverse ecosystems with varying rates of change. Additionally, different species exhibit varying exposure and vulnerability to changing environmental conditions, influenced by factors such as movement patterns, life history characteristics, and thermal ranges.

Ontogeny

Ontogeny, the developmental process of an individual organism from its earliest stages through maturity, plays a crucial role in ecology, particularly in understanding animal behavior and population dynamics. My interest in this field was sparked during my PhD, where I focused on the ontogeny of diving and foraging behavior in penguins and seals. 

By utilizing ARGOS relayed Time-Depth Recorders (TDRs) and accelerometers to closely monitor the behaviors of young king penguins, emperor penguins, and southern elephant seals. These devices enabled us to track the juveniles’ extensive dispersion across the Southern Ocean, their adaptation to local currents and frontal zones, and their spatial segregation from adults. Notably, these juveniles displayed rapid development in diving capabilities, yet they didn't fully match adult efficiency even after a year.

This research revealed the complex nature of the ontogeny of foraging behavior, highlighting the interplay between innate behavior, individual traits, and environmental factors. The insights from these studies have enhanced our comprehension of marine predators' behavior and drawn attention to the crucial first year at sea, a period noted for notable mortality in the three species examined (see a Shiny app below).

Movement Ecology

Movement ecology is a field focused on understanding how organisms move through space and time, specifically looking at the patterns, mechanisms, and consequences of their movements. This discipline is particularly critical in studying animals' habitat selection processes, migration paths, and overall spatial behavior. Tracking devices like ARGOS and GPS, which rely on satellite technology, are instrumental in this field, providing fine-scale location data. These devices allow us to gather detailed, continuous data on individual movements, significantly enhancing our understanding of animal behavior in their natural habitats.

Such tools have revolutionized our understanding of juvenile movement and habitat selection. My interest in this field was particularly piqued by research on juvenile king penguins, as outlined in the article "Exploration during early life: distribution, habitat, and orientation preferences in juvenile king penguins." In this study we tracked juvenile penguins using satellite relay tags, revealing their innate and learned skills in navigating to foraging areas. The research underscored the criticality of the first year at sea for long-lived species and provided unprecedented insights into their distribution, habitat preferences, and orientation. Read a nice summary of this article made by a student for the general public here (in French).

Similarly, in the study "Spatial segregation in a sexually dimorphic central place forager: Competitive exclusion or niche divergence?" involving wandering albatrosses, we used GPS loggers to investigate spatial segregation based on sex. This research delved into the relative importance of intra- and inter-population competition in influencing sex-specific distribution and habitat preferences. The study's results suggested that historical intra-population competition might have led to sexual dimorphism and niche specialization, thus favoring the 'niche divergence' hypothesis.

These studies primarily challenge our understanding of the development of distribution and segregation patterns based on age and sex. Grasping the timing and process of their emergence offers deep insights into the evolutionary dynamics involved, suggesting a combination of spatial memory and inherited migration programs as driving factors. Such findings underscore the significance of investigating behavioral development to better understand complex eco-evolutionary processes.

Dispersal Ecology

Dispersal ecology is a crucial aspect of understanding population dynamics and species distribution. It focuses on the movement of organisms from their birthplace or current location to new breeding habitats. New tracking technologies have the potential to revolutionize this field, allowing for detailed and continuous tracking of individuals over extended periods. Such advancements are vital for longitudinal studies, enabling the observation of the settlement process during natal dispersal with unprecedented precision.

The article "Shift in habitat selection during natal dispersal in a long-lived raptor species" exemplifies the potential of such technologies. By deploying solar-powered GPS-GSM transmitters on nestlings, we could continuously track red kites for up to six years, from fledging to settlement. This long-term tracking allowed for the application of habitat selection functions, revealing how habitat preferences change from the prospecting phase (A, see plot below) of natal dispersal to the more selective settlement phase (B). 

This shift is crucial for conservation efforts, as it reveals the varying environmental constraints and habitat needs at different life stages. Moreover, this indicates that long-term data on habitat selection and natal dispersal can shed light on how populations may expand or relocate in response to environmental changes and anthropogenic pressures.

Continuing our exploration of dispersal ecology in red kites, our subsequent study published in Scientific Reports titled "Imprinted habitat selection varies across dispersal phases in a raptor species" further examines the potential influences of Natal Habitat Preference Induction (NHPI). Utilizing integrated step selection functions, this research investigates how early-life experiences across different natal habitats influence the spatial behavior of these birds from independence to settlement. The findings underscore that red kites initially exhibit a strong preference for habitats resembling their natal environments during the prospecting phase. However, as they transition to the settlement phase, these preferences notably diverge depending on the natal habitat type. Birds from high-altitude or urban settings often avoid similar environments in favor of those that differ—indicative of negative NHPI—while those from regions dominated by farmlands or pastures exhibit a clear preference for similar settings, reflecting positive NHPI. These insights are crucial for understanding how individual variability in habitat preference could affect broader population spatial dynamics and conservation strategies in the face of changing environmental conditions.