ABSTRACT
Harmonious coexistence between humans, other animals and ecosystem services they support is a complex issue, typically impacted by landscape change, which affects animal distribution and abundance. In the last 30 years, afforestation on grasslands across Great Britain has been increasing, motivated by socio-economic reasons and climate change mitigation. Beyond expected benefits, an obvious question is what are the consequences for wider biodiversity of this scale of landscape change. Here, we explore the impact of such change on the expanding population of common buzzards Buteo buteo, a raptor with a history of human-induced setbacks. Using Resource-Area-Dependence Analysis (RADA), with which we estimated individuals' resource needs using 10-day radio-tracking sessions and the 1990s Land Cover Map of GB, and agent-based modelling, we predict that buzzards in our study area in lowland UK had fully recovered (to 2.2 ind km-2) by 1995. We also anticipate that the conversion of 30%, 60% and 90% of economically viable meadow into woodland would reduce buzzard abundance nonlinearly by 15%, 38% and 74%, respectively. The same approach used here could allow for cost-effective anticipation of other animals' population patterns in changing landscapes, thus helping to harmonize economy, landscape change and biodiversity.
Subject(s)
Biodiversity , Ecosystem , Animals , Climate Change , Conservation of Natural Resources , Forests , Humans , United KingdomABSTRACT
An animal's home-range can be expected to encompass the resources it requires for surviving or reproducing. Thus, animals inhabiting a heterogeneous landscape, where resource patches vary in size, shape and distribution, will naturally have home-ranges of varied sizes, so that each home-range encompasses a minimum required amount of a resource. Home-range size can be estimated from telemetry data, and often key resources, or proxies for them such as the areas of important habitat types, can be mapped. We propose a new method, Resource-Area-Dependence Analysis (RADA), which uses a sample of tracked animals and a categorical map to i) infer in which map categories important resources are accessible, ii) within which home range cores they are found, and iii) estimate the mean minimum areas of these map categories required for such resource provision. We provide three examples of applying RADA to datasets of radio-tracked animals from southern England: 15 red squirrels Sciurus vulgaris, 17 gray squirrels S. carolinensis and 114 common buzzards Buteo buteo. The analyses showed that each red squirrel required a mean (95% CL) of 0.48 ha (0.24--0.97) of pine wood within the outermost home-range, each gray squirrel needed 0.34 ha (0.11-1.12) ha of mature deciduous woodland and 0.035-0.046 ha of wheat, also within the outermost home-range, while each buzzard required 0.54 ha (0.35-0.82) of rough ground close to the home-range center and 14 ha (11-17) of meadow within an intermediate core, with 52% of them also relying on 0.41 ha (0.29-0.59) of suburban land near the home-range center. RADA thus provides a useful tool to infer key animal resource requirements during studies of animal movement and habitat use.
Subject(s)
Birds/physiology , Homing Behavior , Sciuridae/physiology , Animal Distribution , Animals , Ecosystem , England , Population Dynamics , TelemetryABSTRACT
The song of the Brazilian population of the Humpback Whale Megaptera novaeangliae was studied in its breeding and calving ground, the Abrolhos Bank, Bahia, Brazil, from July to November 2000. Aural and spectral analyses of digital recordings were completed for approximately 20 song cycles, totaling 5 hours of song from 10 different recording events. We identified 24 note types, organized in five themes. All songs presented the same themes and the order in which they were sung did not vary. We registered the appearance of a note type and the disappearance of a phrase ending, which indicate that the song changed as the season progressed. Moreover, we detected individual variation in the way singers performed certain complex note types. As songs are transmitted culturally, it is likely that singers have different abilities to compose and/or learn new notes. If, as it has been previously suggested, 'new' songs are preferred to 'old' ones, these more able singers will be sending out information about their learning abilities that could be used by other whales to decide whether or not to interact with them.
Subject(s)
Vocalization, Animal/classification , Whales/physiology , Animals , Brazil , Learning , Seasons , Sound Spectrography , Vocalization, Animal/physiologyABSTRACT
Estudamos o canto da população brasileira de Baleia-jubarte Megaptera novaeangliae em sua área de reprodução - a região do Banco dos Abrolhos, Bahia - de julho a novembro do ano 2000. Completamos análises auditiva e espectral de aproximadamente 20 ciclos de canto, em um total de 5 horas de gravaçäes provenientes de 10 ocasiäes diferentes. Identificamos 24 tipos de notas, organizadas em cinco temas. Todos os cantos são formados pelos mesmos temas e não houve variação na ordem na qual foram cantados. Registramos o aparecimento de um tipo de nota e o desaparecimento de uma terminação de frase, o que indica que o canto mudou ao longo da temporada de reprodução. Mais ainda, detectamos variação individual na forma como os cantores emitiam certos tipos de notas mais complexos. Uma vez que o canto é transmitido culturalmente, é provável que os cantores tenham habilidades diferentes para compor e aprender novas notas. Se, como já foi sugerido anteriormente, cantos 'novos' são preferidos a cantos 'antigos', cantores mais capazes estariam mandando informação sobre suas habilidades de compor e aprender que pode ser usada por outros indivíduos para decidir quanto a interagir ou não com eles.
