Northern elephant seals Mirounga angustirostris were extirpated from California in the 19th century, and only in recent decades have they recolonized. A key demographic parameter underlying population viability is the survival of pups, from birth to weaning. We evaluated local factors acting directly on pup survival prior to weaning and basin-wide factors reflecting oceanic conditions which may impact maternal condition and behavior, using a 37 yr time series from 2 adjacent islands off central California: Southeast Farallon Island (SEFI) and West End Island (WEI). Mixed-effects logistic regression indicated that annual pup survival decreased with increasing frequency of extreme waves during January and February, which may inundate haulout locations when pups are present, and increased with the North Pacific Gyre Oscillation (NPGO) index, reflecting increased primary productivity. Moreover, the impact of extreme waves was manifest only for WEI, which may reflect a greater risk of inundation compared to SEFI. Annual pup survival was most highly correlated with NPGO values during the 6 mo period preceding and including arrival and the pupping period (fall and winter). Our findings suggest that favorable foraging conditions for females during the 4 mo prior to hauling out led to better maternal condition, which improved pup survival. Impacts of storm surges on pup survival is of concern since the frequency and severity of storms is expected to increase in the future. To support population recovery, we recommend studies consider demographic parameters such as recruitment of females to the Farallon breeding population and to adjacent coastal California colonies.

Offspring growth rates impact fitness and can be influenced by maternal effects. Despite efforts to understand the influence of maternal traits (e.g. age, size, body condition) on reproductive effort, much less is known about how maternal traits and environment influence the behaviour of offspring and ultimately, how offspring behaviour may influence the efficiency of the translation of maternal investment into offspring growth. Offspring of capital breeders, such as the northern elephant seal, Mirounga angustirostris, are nursed exclusively from maternal body reserves and investment is limited by the resources acquired prior to parturition. Combined new and previously published milk energy intake and offspring storage data (N= 38) suggest impacts of maternal age on growth efficiency that are independent of rates of energy delivery. To determine the mechanisms underlying this effect of maternal age, behavioural data were collected from pups of 46 known-age females, from parturition to weaning, across 6 years and three different sites along the central California coast, representing 3954 seal-hours of observation. Pup behaviours were divided into five mutually exclusive categories that potentially impacted pup energetics. The offspring of older females spent more time resting, while offspring of younger females spent more time locomoting and distant from their mother. As pups developed, they spent more time suckling and locomoting and less time resting. Pup behaviour showed strong diel patterns, with activity decreasing over the day. The magnitude of these relationships varied between rookeries, suggesting influences of harem size, topography or environmental features on pup behaviour. Together these findings suggest direct impacts of maternal age and breeding experience on pup behaviour and growth efficiency. (C) 2019 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Understanding the colonization or recolonization of breeding sites used by colonial animals is fundamental to metapopulation theory and has practical applications in conservation biology. Historically, pinniped species were heavily exploited worldwide, resulting in some breeding colonies becoming extirpated. As populations recover, some abandoned sites may be recolonized or new sites can be colonized. We analyzed aerial and ground survey data on pup counts from 3 islands (South Farallon, San Miguel, and Bogoslof) (re)colonized by northern fur seals (Callorhinus ursinus), using classical and Bayesian state-space modeling approaches to describe population growth rates during their initial 21 years, with particular focus on the South Farallon Islands. We used information from tagged animals that immigrated to the South Farallon Islands from San Miguel Island to describe the age and sex structure of the founding recolonizers of the South Farallon Islands. We also examined the evidence for the generality of Roux's (1987) description of fur seal population recovery using a literature review of published fur seal population growth rates. We found the 3 colonies had different annual population growth rates (South Farallon = 34%, San Miguel = 45%, Bogoslof = 59%), but all were growing at rates among the fastest observed for fur seals worldwide. Immigrants from San Miguel to the South Farallon Islands were younger and female-biased relative to the tagged population at San Miguel Island. The general framework described by Roux (1987) was an effective description of observed fur seal population recovery. Our results inform our understanding of the initiation and growth of pinniped breeding colonies.

The aim of this study was to extend 40 yr of prior demographic work on northern elephant seals (Mirounga angustirostris )a t A~ Nuevo, California, by including the oldest animals. We used a Bayesian mark-recapture analysis to estimate lifelong survival and lifespan of a cohort of 372 weaned pups branded in 1985–1987 and resighted until 2008. Annual survival probability of females averaged 86.3%/yr at ages 5– 16, then declined until age 21, the age of the oldest female. Male survival was lower, averaging 67.7%/yr from age 1 to age 15, the age of the oldest male. Northern elephant seal females in the expanding population at A~ Nuevo live longer than southern elephant seal females (M. leonina) at colonies whose populations are declining. This comparison suggests that high survival of females is a key factor in population growth.

The Farallon Islands in the Gulf of the Farallones National Marine Sanctuary (GFNMS) is a 7-island chain located 48 km west of San Francisco, California. Since 1993, GFNMS biologists and associates have monitored algal and invertebrate species abundances on the intertidal shores of the 2 South Farallon Islands. The monitoring occurred 1–3 times yearly in 6 study areas. In each study area, 3–4 permanent, 0.15-m2 quadrats located between the upper and midintertidal zones were sampled for algal and sessile invertebrate cover and invertebrate counts. Taxonomic surveys were also completed to document other species in the vicinity of the sampling quadrats and to further characterize the sampling areas. Here we report monitoring results for the period 1993 to 2011. While species richness has remained relatively stable and high compared to the nearest mainland sites (Sonoma County through San Mateo County), there has been a slow, long-term net decline in the abundance of algal species and mussels at various sites on the islands. Causes for the declines remain unknown, but increased trampling from rising numbers of pinnipeds and increased waste from pinnipeds and seabirds are among the influences suspected to be important.

We report on the distribution and abundance of the northern elephant seal (Mirounga angustirostris) in the United States from 1991 to 2010. Pup production (i.e., births) was the principal metric used to characterize abundance, distribution, and population growth of the U.S. population and of each rookery in the U.S. Birth estimates were obtained from the literature and estimated from recent counts of adult females or counts of pups made during ground and aerial photographic surveys conducted during the pupping-breeding season at all rookeries in central California and the Channel Islands in southern California. A total of 40,684 pups were estimated to have been born at 11 rookeries in the U.S. in 2010. The two most productive rookeries as of 2010 were San Miguel Island (16,208 pups) and San Nicolas Island (10,882 pups). The Piedras Blancas rookery was not established in 1991 but has since grown to be the fourth largest rookery as of 2010. Rookeries grew most rapidly initially, presumably due to high immigration rates; then increased moderately, eventually becoming stable; and some declined in size. Since 1988, the U.S. population has been growing at an average annual rate of 3.8%. The multiplicative factor needed to estimate total population size from pup production is estimated at 4.4. Total U.S. population size in 2010 was estimated at 179,000 individuals. Using conservative estimates for population growth of northern elephant seals in Mexico, we estimate that the total population in Mexico and the U.S. in 2010 was between 210,000 and 239,000 individuals.