I am pleased to announce the publication of the following two papers focusing on the behavioural response of minke whales towards whalewatching boats on a feeding ground in Iceland.

 

 

Paper 1:

 

Christiansen, F., Rasmussen, M. & Lusseau, D. 2013. Whalewatching boats disrupt the foraging activities of Minke whales in Faxaflói bay, Iceland. Marine Ecology Progress Series 478: 239-251.

 

Abstract:

Human disturbances of wildlife, such as tourism, can alter the activities of targeted individuals. Repeated behavioural disruptions can have long-term consequences for individual vital rates (survival and reproduction). To manage these sub-lethal impacts, we need to understand how activity disruptions can influence bioenergetics and ultimately individual vital rates. Empirical studies of the mechanistic links between whale-watching boat exposure and behavioural variation and vital rates are currently lacking for baleen whales (mysticetes). We compared minke whale Balaenoptera acutorostrata behaviour on a feeding ground in the presence and absence of whale-watching boats. Effects on activity states were inferred from changes in movement metric data as well as the occurrence of surface feeding events. Linear mixed effects models and generalised estimation equations were used to investigate the effect of whale-watching boat interactions. Measurement errors were quantified, and their effects on model parameter estimates were investigated using resampling methods. Minke whales responded to whale-watching boats by performing shorter dives and increased sinuous movement. A reduction in the probability of observing longer inter-breath intervals during sinuous movement showed that whale-watching boat interactions reduced foraging activity. Further, the probability of observing surface feeding events also decreased during interactions with whale-watching boats. This indicates that whalewatching boats disrupted the feeding activities of minke whales. Since minke whales are capital breeders, a decrease in feeding success on the feeding grounds due to whale-watching boats could lead to a decrease in energy available for foetus development and nursing on the breeding grounds. Such impact could therefore alter the calving success of this species.

 

 

 

Paper 2:

 

Christiansen, F., Rasmussen, M. & Lusseau, D. 2013. Inferring activity budgets in wild animals to estimate the consequences of disturbances: Effects of whalewatching boat interactions on minke whales. Behavioural Ecology 24(6): 1415-1425. doi: 10.1093/beheco/art086

 

Abstract:

Activity budgets can provide a direct link to an animal’s bioenergetic budget and is thus a valuable unit of measure when assessing human induced nonlethal effects on wildlife conservation status. However, activity budget inference can be challenging for species that are difficult to observe and require multiple observational variables. Here, we assessed whether whalewatching boat interactions could affect the activity budgets of minke whales (Balaenoptera acutorostrata). We used a stepwise modeling approach to quantitatively record, identify, and assign activity states to continuous behavioral time series data, to estimate activity budgets. First, we used multiple behavioral variables, recorded from continuous visual observations of individual animals, to quantitatively identify and define behavioral types. Activity states were then assigned to each sampling unit, using a combination of hidden and observed states. Three activity states were identified: nonfeeding, foraging, and surface feeding (SF). From the resulting time series of activity states, transition probability matrices were estimated using first-order Markov chains. We then simulated time series of activity states, using Monte Carlo methods based on the transition probability matrices, to obtain activity budgets, accounting for heterogeneity in state duration. Whalewatching interactions reduced the time whales spend foraging and SF, potentially resulting in an overall decrease in energy intake of 42%. This modeling approach thus provides a means to link short-term behavioral changes resulting from human disturbance to potential long-term bioenergetic consequences in animals. It also provides an analytical framework applicable to other species when direct observations of activity states are not possible.

 

Please contact me by email for a copy of these articles if you are interested: f.christiansen@live.se. I will also be attending the SMM conference next week in New Zealand, and present some of these results on Wednesday Dec 11 at 09:00 in Castle 2.

 

Best regards,

 

Fredrik Christiansen

 

Research fellow

Centre for Integrative Ecology

School of Life and Environmental Sciences
Deakin University

Warrnambool Campus, PO Box 423, Warrnambool, VIC 3280
Phone: +61 3 55633080

Email: f.christiansen@deakin.edu.au, f.christiansen@live.se

Publications: http://scholar.google.com.au/citations?user=vkA5Y3EAAAAJ&hl=en&oi=sra