Humpback whales interfering when mammal-eating killer whales attack other species: mobbing behavior and interspecific altruism?

Humpback whales (Megaptera novaeangliae) are known to interfere with attacking killer whales (Orcinus orca). To investigate why, we reviewed accounts of 115 interactions between them. Humpbacks initiated the majority of interactions (57% vs. 43%; n=72), although the killer whales were almost exclusively mammal-eating forms (MEKWs, 95%) vs. fish-eaters (5%; n=108). When MEKWs approached humpbacks (n=27), they attacked 85% of the time and targeted only calves. When humpbacks approached killer whales (n=41), 93% were MEKWs, and >87% of them were attacking or feeding on prey at the time. When humpbacks interacted with attacking MEKWs, 11% of the prey were humpbacks and 89% comprised 10 other species, including 3 cetaceans, 6 pinnipeds, and 1 teleost fish. Approaching humpbacks often harassed attacking MEKWs (>55% of 56 interactions), regardless of the prey species, which we argue was mobbing behavior. Humpback mobbing sometimes allowed MEKW prey, including nonhumpbacks, to escape. We suggest that humpbacks initially responded to vocalizations of attacking MEKWs without knowing the prey species targeted. Although reciprocity or kin selection might explain communal defense of conspecific calves, there was no apparent benefit to humpbacks continuing to interfere when other species were being attacked. Interspecific altruism, even if unintentional, could not be ruled out

Predator Influences on Behavioral Ecology of Dusky Dolphins

I developed a spatially explicit individual-based model (IBM) to capture the dynamic behavioral interaction between a fierce predator (killer whale, Orcinus orca) and a clever prey (dusky dolphin, Lagenorhynchus obscurus), and to answer the ultimate question of costs vs. benefits for dusky dolphins when making anti-predator decisions. Specifically, I was interested in calculating time/distance budgets for dusky dolphins in the presence/absence of killer whales and the presence/absence of movement and behavioral rules, which presumably evolved in response to spatial and temporal variations in predation risk. Results reveal that dusky dolphins rest less, travel more and have reduced foraging time when killer whales are present. These effects are more pronounced with increased presence of killer whales. The model suggests that a strong reason favoring the adoption of short and long-term anti-predator mechanisms is increased survival resulting from decreased encounters with killer whales. Further, a mother with calf rests less and travels more when killer whales are present relative to a dolphin without calf. However, a mother with calf on average, flee shorter distances and have fewer encounters with killer whales than a dolphin without calf. Thus, despite ecological costs, it makes evolutionary sense for dusky dolphins to adopt anti-predator rules. Bioenergetic consequences for dusky dolphins with and without calf were estimated as total energetic costs and foraging calories lost due to low/high presence of killer whales. I calculated total energy costs as: Foraging costs (FC) Locomotor costs (LC) (Travel) or LC (Travel) LC (Flee) based on the absence, as well as low/high presence of killer whales. Foraging costs contributed significantly to total energetic costs estimated. Travel costs are minimal owing to proximity to deep waters. The total energy costs were not significantly higher from low or high presence of killer whales for mother with calf, but increases by about 90 kcal/day for a dusky without calf. However, I estimate foraging calories lost due to increased killer whale presence is almost 5 times more for mother with calf. Therefore, it might be important to consider indirect predation risk effects by social type in future studies on animal bioenergetics

Using non-systematic surveys to investigate effects of regional climate variability on Australasian gannets in the Hauraki Gulf, New Zealand

Few studies have investigated regional and natural climate variability on seabird populations using ocean reanalysis datasets (e.g. Simple Ocean Data Assimilation (SODA)) that integrate atmospheric information to supplement ocean observations and provide improved estimates of ocean conditions. Herein we use a non-systematic dataset on Australasian gannets (Morus serrator) from 2001 to 2009 to identify potential connections between Gannet Sightings Per Unit Effort (GSPUE) and climate and oceanographic variability in a region of known importance for breeding seabirds, the Hauraki Gulf (HG), New Zealand. While no statistically significant relationships between GSPUE and global climate indices were determined, there was a significant correlation between GSPUE and regional SST anomaly for HG. Also, there appears to be a strong link between global climate indices and regional climate in the HG. Further, based on cross-correlation function coefficients and lagged multiple regression models, we identified potential leading and lagging climate variables, and climate variables but with limited predictive capacity in forecasting future GSPUE. Despite significant inter-annual variability and marginally cooler SSTs since 2001, gannet sightings appear to be increasing. We hypothesize that at present underlying physical changes in the marine ecosystem may be insufficient to affect supply of preferred gannet main prey (pilchard Sardinops spp.), which tolerate a wide thermal range. Our study showcases the potential scientific value of lengthy non-systematic data streams and when designed properly (i.e., contain abundance, flock size, and spatial data), can yield useful information in climate impact studies on seabirds and other marine fauna. Such information can be invaluable for enhancing conservation measures for protected species in fiscally constrained research environments.Fil: Srinivasan, Mridula. National Marine Fisheries Service; Estados UnidosFil: Dassis, Mariela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Benn, Emily. University of Sydney; AustraliaFil: Stockin, Karen A.. Massey University; Nueva ZelandaFil: Martinez, Emmanuelle. Massey University; Nueva Zelanda. Pacific Whale Foundation; Estados UnidosFil: Machovsky Capuska, Gabriel E.. Massey University; Nueva Zelanda. University of Sydney; Australi

Marine Mammal Mass Strandings

The folder provides additional reference materials and resources about dealing with marine mammal mass strandings

Euthanasia

The document is a guideline. It is imperative that expert help and advice and permissions obtained before any decision is taken.This is a primer on factors to consider if employing euthanasia for stranded animals

Pinniped Stranding Response Resources

The folder provides additional resources for pinniped stranding response training (both live and dead

Stranding Response Forms

The folder provides sample stranding response forms for data collection from cetaceans and pinnipeds. Forms can be modified to suit regional purposes

Marine Mammal Stranding Response Introductory Resources

This folder contains introductory information on why stranding response activities are important for marine mammal research and conservation. Additional introductory species information for pinnipeds is also provided

Mass Marine Mammal Stranding Response

This is a primer on mass cetacean strandings and provides an overview of the various factors to be considered in dealing with mass-stranded animals