data viz

Landscape of a Year by Michael Johns

Animals tend to be fairly predictable in their reproductive timing and migration patterns. The figure above depicts a series of density curves, with peaks and troughs corresponding to the average timing of key biological events for a select number of marine species that are monitored on or from Southeast Farallon Island.

Pinnipeds, a taxonomic group that includes seals and sea lions, are found hauled out on the island year round, with peak pupping events occurring in the summer. Northern fur seals, which have made an astounding recovery on the Farallones following the days of the Russian Fur Trade, remain at sea for several months of the year and are only seen in force from summer to late fall. Whales are also visible from the island year round. Gray whale numbers peak in January as they migrate south to their breeding grounds off Baja California Mexico, and again in March during a northward migration back to their feeding grounds in Alaska. Humpback and blue whales are most abundant in the productive summer months, where they are seen gorging themselves on krill and schooling fish. For seabirds, breeding occurs only in the summer months, with the exception of the ashy storm-petrel which extends chick rearing well into October. Three distinct peaks represent the timing of egg laying, hatching, and chick fledging. 

The study of seasonal life-history patterns is called phenology, and it can tell us a lot about the stability of a system. As I mentioned, animals tend to be fairly predictable in their phenology. Individuals cue in on environment and biological signals, so shifts in the timing of reproduction or migration can indicate changes in environmental condition, food availability, or the health of a population. For species found on the Farallones, the major cause for concern in the face of a warming ocean is the availability of key prey items, namely krill, which sustain the rich biodiversity in this region. A mismatch between the timing of krill and the timing of reproduction for seabirds can lead to major declines in breeding success, and subsequent declines in population numbers. 

Data courtesy of a partnership between Point Blue Conservation Science and the USFWS. The plot was created in R with the ggplot2 and ggridges packages. 

Relative Size by Michael Johns

Probably the most important question in the conservation work that we do, and the most popular question people have about the Farallones, is the population size of the various seabird species on the island. The answer, such as roughly 250,000 murres, 20,000 auklets, and 500 puffins, may not be fully appreciated when taken at face value. The figure above is an attempt to put these numbers into context by representing each population as a collection of boxes, where the area of each box is scaled in proportion to the other boxes. With this visualization, you can see just how abundant Common Murres are in relation to Pigeon Guillemots or Tufted Puffins. With continued monitoring and management, hopefully all of these boxes will continue to grow in size.

Data courtesy of a partnership between Point Blue Conservation Science and the USFWS. The plot is called a "Treemap", created in R with the ggplot2 and treemapify packages. 

50 Years of Bands by Michael Johns

It's been 50 years since scientists from Point Blue Conservation Science (then Point Reyes Birds Observatory) began a continuous monitoring effort on SE Farallon Island. Some of this work includes banding certain species of seabirds to learn more about their movement patterns, survival and mortality rates, population status, and individual breeding behavior and success; all important information guiding management decisions and tracking the potential effects of climate change. Point Blue has amassed an impressive sample of banded birds since work first started in 1967, totaling nearly 125,000 individuals as of 2016. The graphic below illustrates the total bands put out by year and cumulatively since 1967 for 8 target species.