About This Project

Humpback whales that summer in California make their way to Central America each winter, and many find their way to calving waters off the coast of Costa Rica. Using a growing fluke catalog of the California whales, I'll be identifying specific animals at specific times during their winter stay in Costa Rica. And I'll be conducting some behavioral studies of mothers and calves to see how their choices compare with other humpback populations.

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What is the context of this research?

Several years ago I joined ongoing studies of Hawaii’s humpback population. One of our recent observations was that whale habitat choices in the Au’Au channel seem to be changing, and responding to their environment (Cartwright, Gillespie, et al., 2012). In those waters, the humpbacks seem to avoid regions of intense boat traffic, suggesting that they are sensitive human contact, especially boat-traffic. Do the Drake Bay humpbacks display similar habitat preferences? Do their choices vary over the breeding season?

As well, in the Hawaiian population calf age has been correlated both to the furling of their dorsal fin and calf swim/rest behavior (Cartwright, et al., 2009). In the Au’Au channel, calves have been observed rest more as they mature, diving more often and deeper, and traveling less. We will determine whether these observables correlate similarly in Costa Rican waters. If these behaviors are stimulated by developmental changes in the calf, then similar behavioral profiles are expected, regardless of nursery area. Do calf dorsal furls correlate to breathing patterns in Drake Bay, as they do elsewhere?

Fluke comparisons are a standard tool for monitoring movement of whales among feeding and breeding waters (Seton, et al., 2002. As efforts at understanding the California population of humpbacks grow, it is increasingly critical to map the nursery habitat usage of those animals. While observations linking animals in California and Drake Bay have been made (ref), no comprehensive effort has been made to collect and correlate fluke images from these regions. How many California whales can we map to Drake Bay?

This project is being undertaken in conjunction with Fundación Keto, Costa Rica's premiere nonprofit dedicated to marine and costal resource management. We will leverage the skills and local experience of Keto's personnel, to ensure we work efficiently and with utmost respect for Costa Rican ecology, and ecological sciences.

What is the significance of this project?

Humpback whale populations are recovering from the commercial whaling era of the 19th and 20th centuries. Though the North Pacific population is being considered for delisting from under the Endangered Species Act, their migration between habitats makes humpback management complex. Our work seeks to directly link monitoring efforts of the California group of whales to their nursery waters in Costa Rica.

Building a fluke catalog of this population - both for our own research purposes and for inclusion in general monitoring efforts – is part of establishing migration and family histories for this sub-group of whales. As the Californian subpopulation continues to rebound, our studies will help provide baseline data and perhaps allow interpretation of changes in population/behavior over time.

A map of whale distribution in their nursery waters means we can begin to understand what kinds of habitat humpbacks prefer. Do females with calves choose different spots that solitary whales or groups? It has been suggested that this is the case for some populations; our work will help show whether habitat selectivity is a general feature of humpback populations. As well, understanding the factors that govern humpback habitat choice may help us improve conservation efforts.

What are the goals of the project?

• Fluke comparisons
• Social stratification
• Behavior & calf- age
• Changes over the season

Flukes
We want to know exactly which whales are making their way to Drake Bay, so we’ll be taking high-quality photographs of whale flukes. By comparing these to flukes in existing catalogs, we will be able to identify these animals, and begin building a history of their travels.

Distribution
We will map the location of all our observations in the waters between Drake Bay and Isla Caño. Using a combination of systematic, transect-based surveys and opportunity-based sightings, we will observe how this population is distributed across the region.

Behavior and calf-age
We will conduct focal follows to monitor the behavior of animals across all types of humpback social groups. We will correlate these observations with calf age, to determine whether behavioral patterns and developmental switches compare with humpbacks’ behavior in their Hawaiian nursery.

Seasonal variation
Since we’ll be monitoring the population over an extended period (Feb-June), we can also observe how population, distribution, and behavior change over the whole breeding season.