Kevin A. Wood

Conservation Conflicts: Future Research Challenges

It has been long known that wildlife management is often more about working with people than with wildlife (Gilbert 1971). Much of this people management occurs as top down conservation measures codified in rules, regulations, and laws. When such measures are enforced, or when there is an absence thereof, both people and wildlife can be affected; this has the potential to give rise to conflict about these measures to conserve wildlife. Such conservation conflicts have the potential to be as widespread as they are varied, and have proven difficult to resolve. It is also clear that conservation conflicts that involve wildlife will escalate both in number and intensity in the future because of rising human population and resource use (Redpath et al. 2015).

Plants in aquatic ecosystems: current trends and future directions

Aquatic plants fulfil a wide range of ecological roles, and make a substantial contribution to the structure, function and service provision of aquatic ecosystems. Given their well-documented importance in aquatic ecosystems, research into aquatic plants continues to blossom. The 14th International Symposium on Aquatic Plants, held in Edinburgh in September 2015, brought together 120 delegates from 28 countries and six continents. This special issue of Hydrobiologia includes a select number of papers on aspects of aquatic plants, covering a wide range of species, systems and issues. In this paper, we present an overview of current trends and future directions in aquatic plant research in the early twenty first century. Our understanding of aquatic plant biology, the range of scientific issues being addressed and the range of techniques available to researchers have all arguably never been greater; however, substantial challenges exist to the conservation and management of both aquatic plants and the ecosystems in which they are found. The range of countries and continents represented by conference delegates and authors of papers in the special issue illustrates the global relevance of aquatic plant research in the early twenty first century but also the many challenges that this burgeoning scientific discipline must address.

Understanding intrinsic and extrinsic drivers of aggressive behaviour in waterbird assemblages: a meta-analysis

Aggressive behavioural interactions between animals are widespread in nature, with ecological and evolutionary consequences of such interactions reported for both individuals giving and receiving aggression. Yet despite the importance of aggressive interactions in determining social dominance and conferring fitness benefits to successful individuals, we lack a general understanding of the conditions that influence the variation in agonistic behaviours among individuals and species. We conducted a global meta-analysis of published time–activity budgets, using a data set comprising 555 values from 88 studies, to determine variation in the time that waterbirds engaged in aggressive interactions. The meanxa0±xa0SD percentage of time devoted to aggression was 2.0xa0±xa03.6%, with a range of 0.0–35.0%. We used our data set to test four predictions regarding avian aggression, based on the findings of earlier site-based studies. We predicted that the time spent on aggression would be influenced by four factors: (1) age class, (2) sex, (3) seasonal timing and (4) functional feeding group. A comparison of linear mixed-effects models using an information theoretic approach indicated that the proportion of time waterbirds spent engaged in aggressive interactions was best explained by the age class and sex of the focal waterbird species. More time was spent on aggression by males than females, and by adults than juveniles. We found no evidence that the time spent on aggressive behaviours varied across latitudes or body mass, with seasonal timing, sexual dimorphism, migration or breeding strategies, or between different functional feeding groups. Our findings highlight the high levels of variation in the time devoted to aggression across species, feeding groups, latitudes and seasons. Furthermore, our study demonstrates the utility of the numerous published time–activity budget studies that are available as a valuable source of data that can be used to answer broad-scale questions regarding animal behaviour.

Has winter body condition varied with population size in a long-distance migrant, the Bewick’s Swan (Cygnus columbianus bewickii)?

Assessments of body condition can provide useful information on changes in the state of individuals within a population, which may in turn help to inform conservation efforts. For example, decreases in body condition over time can indicate reduced food resources. Mass and skull length measures recorded for 195 adult and 467 first winter (cygnets) Bewick’s Swans (Cygnus columbianus bewickii) at wintering sites in the UK between winters 1966/1967 and 2017/2018 therefore were analysed to determine whether a ca. 40% decline in numbers in the Northwest European Bewick’s Swan population between 1995 and 2010 corresponded with poorer body condition from the mid-1990s onwards. Parents and siblings were known for all individuals, allowing us to account for shared genetic factors and rearing environment in our analysis. We used linear mixed-effects models and an information-theoretic approach to test different models of temporal variation in scaled body mass index (SBMI). Within our study population, although SBMI values varied both within and between years, we found no evidence of any directional trends in body condition. Of our competing time models of swan SBMI, a model in which age-specific body condition was constant over time received the greatest support in the data. Body condition was greater for adults than cygnets, but did not vary between sexes or wintering sites. Our findings suggest no connection between the recent declines in population size and body condition. Population decline is therefore unlikely to be caused by inadequate food supplies.