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Restoring Habitat and Conserving Biodiversity
on an Island Refuge
Año Nuevo Island off central California, USA ( 37º 06.30' N, 122º 20.09' W) - click to enlarge
What's New? Journal Update - View Film of novel restoration
techniques
Adult Rhinoceros Auklet in breeding plumage (Photo: Frank Balthis) Project Leaders Michelle
Hester, Oikonos Funders and Collaborators
California State Coastal
Conservancy State of California Parks and Recreation,
Año Nuevo State Reserve Table of Contents (click to skip ahead) Project Summary
Año Nuevo Island, part of Año Nuevo State Reserve, is one of only four significant island refuge regions with protected habitat for marine birds and mammals in California. The island habitat has been completely altered by past human use resulting in almost complete absence of native vegetation. The current rate of erosion due to destabilization and loss of topsoil threatens the remnant habitat for nesting seabirds, and other island species. Seven marine bird species regularly use the island for rearing young and over fourteen bird species use the island for stopover and roosting habitat during the non-breeding seasons. After evaluating the condition of island natural resources, the Año Nuevo State Reserve management plan recommended revegetation to provide additional bird habitat and slow topsoil erosion (Lewis and Tyler 1987). However, no habitat restoration or direct erosion control has occurred to date. Presently, the species most affected by habitat degradation on the island is a burrow-nesting seabird, the Rhinoceros Auklets (Cerorhinca monocerata). After 1997, when the island became virtually denuded, the rates of burrow collapse and subsequent injury have increased and there are fewer breeding birds occupying natural nest sites. In addition, injury due to oil contamination from episodic leakages of the sunken S.S. Jacob Luckenbach and other recent oil spills further threaten this breeding population. The main goal of this restoration project is to improve soil stability and increase habitat diversity on the central marine terrace region, the main habitat for burrowing seabirds. We predict this can be accomplished with 3 years of intensive restoration, followed by 4 years of secondary adaptive maintenance and studies to quantify the success of restoration efforts. Overarching goals of this project include the restoration of natural processes and long-term conservation of biodiversity. By revegetating the core of the island, we will not only provide a stable habitat for the burrow-nesting seabirds, but also provide a habitat refuge for insects, songbirds, and native plants. In 2002 we began feasibility studies and restoration experiments with in-kind donations from Go Natives, PRBO, Oikonos, UCSC, and Año Nuevo State Reserve. From our efforts to date we have learned that 1) burlap ground cover works well to retain topsoil and is brittle enough to allow auklets to burrow into, although different materials may be necessary in more rapidly eroding areas, 2) two plant species, native salt grass (Distichlis spicata) and Lizardtail (Eriophyllum staechadifolium), installed in November 2002 survived the winter and are growing well, and 3) little growth from the native seeds is visible; it appears most seed blew away before sprouting. In spring 2003 the project will focus on installing more plots to test additional native species tolerance and experimenting with different erosion control techniques. Ideally, we hope to develop funding for large-scale planting in fall 2003.
Eroding denuded habitat on Año Nuevo Island (Photo: Julie Thayer) 1) Improving habitat diversity and soil stability in the central marine terrace region (approximately one acre, see map), the main habitat for burrowing seabirds. This will be accomplished through planting native shrub and grass assemblages and using temporary ground-cover to reduce erosion until natural vegetative processes are restored. No pinniped exclosures or other structures are necessary. 2) Conduct multi-species studies to quantify the response of wildlife communities to improved habitat quality. 3) Provide valuable knowledge on island habitat restoration techniques to apply elsewhere. Numerous islands suffer from similar habitat perturbations (e.g. Castle Rock, Del Norte County, CA) and learning how to restore natural processes to extreme island environments will increase our ability to conserve populations, biodiversity, and precious island ecosystems. Map of Restoration Area- click for higher resolution map
Gray shading - burrowing seabird habitat; Green - central marine terrace area proposed for restoration Justification - Why Revegetate?
Rhinoceros Auklets - Why is Año Important? Protecting the habitat on Año Nuevo Island for burrowing Rhinoceros Auklets is important because 1) this species has special protection status in the region, 2) the island is one of only three main colonies in California, 3) there are few colonies in the eastern Pacific where demographic information can be obtained, and 4) studying species at the edge of their geographic range provides knowledge about how populations respond to large-scale environmental and biotic changes that leads to wise management. Rhinoceros Auklets are listed as a California Bird Species of Special Concern by the California Department of Fish and Game due to their small population size, high breeding concentration in a restricted range, vulnerable habitat and ongoing mortality due to oil contamination. They are also listed as a "species of high priority management need" by the US Fish and Wildlife Service (USFWS). The last population estimate of Rhinoceros Auklets in California was roughly 1,700 breeding individuals concentrated at only three main colonies in the state (Carter et al. 1992). Since Año is the only colony where accurate population size is quantified annually, it is not known what percentage of California breeders depend on Año Nuevo; roughly perhaps 15% (224 breeding birds in 2002; Thayer and Sydeman 2002). The importance of this colony to our understanding and conservation of this species lies in the fact that this is one of very few colonies in the eastern Pacific where population dynamics can be quantified. Additionally, being at the edge of the species range, responses to climate change and other pressures are more measurable. What makes this island unique for studying burrowing seabirds is the near shore accessibility and small area enabling banding studies that provide comprehensive information not well known for this species: juvenile recruitment parameters (including age-at-first-breeding), age and sex specific survivorship, colonization processes, and energetic requirements. In addition to providing valuable demographic knowledge, investigating this colonizing species will provide clues to how this species responds to environmental and biotic changes. Little is known about the mechanisms and causes of colonization and range shifts. Population level responses are most evident at a species distribution edge and this is where the effects of climate change and other pressures are often most easily measured (Root and Schneider 2002). Interestingly, Rhinoceros Auklets have expanded their range southward during recent decades of oceanic warming and in general, this pattern has been contrary to the pattern expressed by other 'cool-water' diving species (Ainley et al. 1995, Veit et al. 1996, Wahl and Tweit 2000, Sydeman et al. 2002, Ainley and Divoky 2001). Understanding these response patterns improves our ability to manage appropriately as populations fluctuate. Read more about Rhinoceros Auklet population status in California - click here What Happened to the Vegetation? The plant assemblage on the island prior to the building of the lighthouse facility probably resembled that on windward Año Nuevo Point, to which it was connected by land above high tide at least during the 18th century (Le Boeuf and Kaza 1981). A natural progression towards more salt, wind and guano tolerant species likely occurred as the island became more exposed and separated from the mainland point. Human disruption of the native plant community began in 1896 with the purchase of the island by the federal government for the establishment of a lighthouse facility. Little information exists about the use of the island by indigenous cultures, foreign sealers and eggers, or early ranchers. Since 1904, essentially the entire marine terrace was fenced in, exotic gardens were planted and maintained with fresh water cisterns, and marine birds were surely discouraged from attending. Upon human extirpation, pinnipeds began occupying the space and denuded the marine terrace in the northern and southernmost portions of the island, where auklets have not colonized (except around and under the old lighthouse residence building). When Rhinoceros Auklets began colonizing Año Nuevo Island in the early 1980s, the central marine terrace was dense with vegetation, mainly exotic species (Lewis and Tyler 1987). By the mid 1990's, the density of vegetation began to thin and be dominated by exotic Malva and Tetragonia species in areas used by burrowing auklets (Hester 1998). After the 1998 El Niño, there was a rapid increase in erosion and almost complete disappearance of vegetation in auklet breeding areas. The rapid plant die off is speculated to have been caused by dry summer conditions followed by heavy winter rains that washed away the remaining exotic seed bank. In addition, numbers of roosting Brown Pelicans increased on the island, as is typical in ENSO warm water periods when breeding attempts are abandoned in southern California, and the remaining exotic seed cover was not adapted to intense sporadic seasonal trampling. In exposed habitat away from buildings and fences, currently, only sparse patches of native salt grass (Distichlis spicata) exist.
Photos showing the change in vegetation cover from 1994 (top) to 2001 (bottom) in auklet nesting area 1 on Año Nuevo Island. (Photo: Michelle Hester, Julie Thayer) Pinnipeds are often the first to be blamed for the loss of vegetation, as is certainly the case in the northern and southern most portions of the island which are easily accessible to sea lions. However, revegetation feasibility studies conducted by PRBO and pinniped census data from University of California Santa Cruz (UCSC) indicate the central portion of the marine terrace is not used regularly by seals or sea lions. This central portion is the main area for burrowing seabirds and the only area planned for erosion control and planting. Injury due to Oil Contamination Rhinoceros Auklets have received little attention during natural resource damage assessments in California, despite the documented injury, often second only to Common Murres (Apex Houston, Page et al. 1990). Not all seabirds in California are equally threatened by oil spills. There has been numerous studies documenting the sensitivity of Rhinoceros Auklets to oiling events (Page et al. 1990, Helm et al. 1997, Nur et al. 1997, Sato 1999, Oka and Masaki 2000) and the location of almost half the California breeding population (Año Nuevo and Farallones combined) near tanker routes and aging sunken vessels increases the potential for substantial injury. S.S. Jacob Lukenbach (Continual
and episodic releases since 1992 to present , and perhaps since 1972) T/V Command (September-October
1998) Colony studies on Año Nuevo Island document Rhinoceros Auklets in the area in mid September (Thayer/PRBO unpublished data). The number of Rhinoceros Auklets breeding on Año Nuevo Island in 1998 was approximately 175 birds (Figure 2). In 1998, the last monitored Rhinoceros Auklet chicks fledged from burrows between 14 and 21 September, therefore, in addition to adults, hatch-year birds were potentially in the contaminated area. Most years there is evidence of fresh digging by adults on the island as late as September (Hester 1998). This post-breeding digging is suspected to be activity by prospecting adults and/or breeders maintaining territories and pair bonds. Rhinoceros Auklets at sea. (Photo: Greg Lasley) In the fall and winter, the Rhinoceros Auklets in waters off central California are a mixture of birds that reside in the region year round and northern populations that migrate south after the breeding season, although no studies have been conducted to evaluate colony or age-specific migration patterns. In late September and early October 1998, it is likely that individuals from both the resident California population and northern populations were in the spill area between San Francisco and Año Nuevo Island Apex Houston (January-February 1986) Other Benefits to Island Ecosystem Restoring the plant community has numerous benefits beyond stabilizing the soil for burrowing seabirds (Rhinoceros and Cassin's Auklets). The restored area will provide passerines, shorebirds, and other species nesting and stopover habitat free from exotic predators. In addition, vegetation will provide visual cover to reduce negative interactions between resident species (e.g. kleptoparasitism, predation) and reduce researcher disturbance. Other island species that will likely benefit from restoration efforts include Pigeon Guillemots, Brandt's and Pelagic Cormorants, Brown Pelicans, Black Oystercatchers, Ashy and Fork-tailed Storm-petrels, Peregrine Falcons, Western Gulls, Heermann's Gull and numerous other migratory marine bird species. In particular, Brandt's Cormorants, which were injured in recent oil spills, will likely benefit from this project as vegetation will provide more suitable nesting space protected from disturbance and a source of nesting material (approximately 320 breeders have colonized an area on the central marine terrace near large cement blocks). The restored area may also provide songbirds, shorebirds, and other species nesting and migratory stopover habitat free from exotic predators. White-crowned Sparrows and Killdeer (Le Boeuf and Kaza 1981) once bred on the island before vegetation disappeared. Other benefits to this island refuge not mentioned above include increasing habitat for amphibians, pollinators and other terrestrial invertebrates that once inhabited the island. The evidence of past use of the island by indigenous cultures has literally blown away and soil stabilization will enable the investigation of remaining artifacts (Mark Hylkema, State of California Cultural Resources Manager, pers. comm.). There will also be numerous opportunities to educate the public about the consequences of oil transport and raise awareness of seabird sensitivity by collaborating with programs already in place at Monterey Bay and Gulf of the Farallones National Marine Sanctuaries, Año Nuevo Visitors Center and Docent Program, PRBO Education Program, and others. Long-term conservation of the seabird populations and island biodiversity in general is the overarching goal. This project involves maintenance and upkeep during initial establishment, after which time natural processes and dynamics of community succession, erosion, and plant distribution will occur without human manipulation. Islands pose different challenges for habitat restoration than most coastal areas near highways. In addition to logistic difficulties with access and transport, the weather and ocean elements are more variable and extreme. Among coastal restoration experts, there is acknowledgment that a period of trial and error is needed for success in any habitat. The small size of the area to be restored (0.94 acres) increases the feasibility of revegetation, although it also complicates the approach. There is little space to experiment and little space for the dynamics of plant succession and distribution to occur. Much of the habitat is near the margins where exposure to wind and salt is high (and where auklets prefer). Therefore, many factors (ground-nesting gulls, roosting pelicans, variable rainfall, heavy winds) lead to the recommendation that an aggressive approach with grown plants in dense concentrations is likely the best way to succeed at establishing a plant community on this portion of the island. Actions taken to ensure the restoration plan is technically and procedurally sound include collaboration with experts, conducting feasibility studies and gathering data on island use by wildlife, testing plant species and erosion control techniques on the island, and assembling a restoration review committee. The timing and methods of planting will be crucial to the success of this project. The main factors affecting the success of plant survival during initial stages include the degree of trampling and plant-pulling by ground-nesting and roosting seabirds and the harsh and variable environmental conditions. Spring and summer is an active period for nest building gulls and rainfall is minimal. During winter, gull numbers decline significantly, Brown Pelicans roost in the area sporadically, cormorants roost in consistent low numbers, and despite the peak in total sea lion attendance, the restoration area is not occupied by pinnipeds (Figure 4). The preferred roosting sites for these species are on the rocky margins, islets, and beaches. Therefore, we predict the appropriate timing for planting is in late fall, after the gull nesting season, prior to peak attendance by pelicans, and near the start of annual rains. Initial testing has begun for appropriate plant species and erosion control methods taking into account the variable winds, salt influence, resiliency to periodic trampling, growth season, water requirements, and logistical constraints of transportation. Ten test plots were installed in 2002. As of March 2003 we have learned that the native salt grass assemblages survived the winter and are spreading, burlap ground cover is working well to retain topsoil, and auklets are digging nesting burrows in the plots (see journal).
Native Shrubs, seeds under burlap, sticks to discourage interested gulls. (Photo: Michelle Hester) Ideally, we hope to install more test plots as soon as possible concentrating on erosion control in the most significant seabird areas and experimenting with more native species. Further action will involve the establishment of a restoration review committee with a panel of botanists, restoration ecologists, marine ornithologists, and managers. Given the lack of restoration efforts such as this on offshore islands, it is our hope that knowledge gained during this project can be applied to other islands that have degraded habitat from human use and/or introduced species and are in need of restoration to conserve wildlife populations. There are many significant factors that make this an ideal time to proceed with restoration efforts. Project costs will be reduced by in-kind support from Año Nuevo State Reserve, PRBO Conservation Science, UC Santa Cruz, and the UC Natural Reserve System that logistically supports mutually beneficial work on the island ecosystem. The proposed project funding is for direct restoration actions and data collection to determine the success of the project. Costs for small boat operations and storage/research facilities are provided by these other sources with this project only augmenting gas, some safety equipment, and water catchment improvements for the restoration. Substantial in-kind donations from Go Natives Nursery will reduce the cost of plan development and the time, space and materials needed to propagate and grow appropriate native plants in the needed quantity. Go Natives currently has gallon-size native plants from the "San Mateo County coast side region" for large-scale coastal restoration. The value of this cannot be overemphasized considering that dense installation of grown plants is likely the key to establishing a plant community on Año Nuevo Island (as discussed above). In addition, the development of this project has depended on Go Natives donations to test plant resiliency to harsh island conditions and erosion control methods on the island and assist with developing restoration plans prior to receiving any funding. An extensive volunteer network already established will reduce costs when more people are required (e.g. installing plants, collecting seed). Although, due to the high sensitivity of wildlife on this refuge and dangerous transport across the channel, only experienced volunteers in limited numbers will be utilized regularly. Based on ten years of collective experience managing research on Año Nuevo Island, we have learned that the effort expended on coordinating volunteers and assuring their safety is a position in itself. Therefore, instead of hiring a volunteer coordinator, this project will employ an intern that will become experienced in working on the island and reduce time needed to train new volunteers every trip. Transportation costs to the island are further reduced by trip coordination with collaborators from UCSC who also regularly conduct studies on the island; we attempt to combine resources and plan trips to limit the number of "landings" on the island. Long-term cost effectiveness will hopefully be the result for agencies responsible for conserving marine wildlife on the island. Once the plant community is established, it reduces energy required to protect burrowing auklets and other wildlife. Project Needs - Interested in helping? Oikonos and PRBO are nonprofit organizations under section 501(c)(3) of the US Internal Revenue Code. Your contributions are tax-deductible. The project needs financial assistance. Your donation will go directly to revegetating the island (or any other project component you choose). Contact "Michelle at oikonos dot org" if you are interested in helping and would like more information: (415) 868-1399 Send donations to: Oikonos PO Box 1932 As an option, Donations can be made securely online:
Your donation is very needed and appreciated!
Julie Thayer, PRBO
Hester, M.M., J.A. Thayer, W.J. Sydeman, S. Ralston, K. Sakuma. In Prep. Diet and prey selection in a recently recolonized population of Rhinoceros Auklets in the California Current. Hester, M.M. 1998. Abundance, reproduction, and prey of Rhinoceros Auklet, Cerorhinca monocerata, on Año Nuevo Island, California. Masters Thesis, Moss Landing Marine Laboratories, California State University San Francisco, California. Lewis, D.B. and B. Tyler. 1987. Management recommendations for coastal terrace and island resources at Año Nuevo State Reserve. Unpublished Report to California Department of Parks and Recreation, Año Nuevo State Reserve. Institute of Marine Sciences, University of California Santa Cruz. McChesney, G.J., H.R. Carter, and D.L. Whitworth. 1995. Reoccupation and extension of southern breeding limits of Tufted Puffins and Rhinoceros Auklets in California. Colonial Waterbirds 18:79-90. Root, T.L. and S.H. Schneider. 2002. in Wildlife Responses to Climate Change: North American Case Studies (EDs. Schneider, S.H. and Root, T.L. ) Island Press, Washington DC. Thayer, Julie A. and William J. Sydeman. 2002. Breeding biology and ecology of Rhinoceros Auklet, Cerorhinca monocerata, on Año Nuevo Island, California, 2002. PRBO unpublished report to National Fish and Wildlife Foundation. Thayer, J.A., M.M. Hester, and W.J. Sydeman. 2000. The Conservation Biology of Rhinoceros Auklets on Año Nuevo Island, California, 1993-1999. Endangered Species Update 17-3:63-67. (link to abstract)
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