top of page


One-hundred-and-forty-one-year stable isotope record suggests changing distributions but little shift in trophic positions within a resident northern New Zealand seabird community


Globally, human population growth, its associated pollution and the vast scale of industrialised fisheries are having negative impacts on oceanic food webs, affecting top predators such as seabirds. We used stable isotope (δ ¹⁵ N and δ ¹³ C) analyses of feathers to investigate the contemporary structure and long-term changes in a near-shore community of 5 seabird species in northern Aotearoa New Zealand. Feathers were collected from museum specimens or live individuals (collected between 1878 and 2019) in Tīkapa Moana, the Hauraki Gulf, a marine habitat increasingly threatened by overfishing and urbanisation. To tease out the effects of baseline ecosystem versus seabird distributional changes, we analysed muscle isotope values of forage fishes collected over 43 yr (1976-2019) and provide isotopic data from contemporary prey species sampled within the region. Contemporary δ ¹⁵ N and δ ¹³ C values were consistent with existing data on diet and foraging distribution of the 5 seabird species. Values of δ ¹⁵ N declined in only 1 of 5 species studied, suggesting little change in the trophic position of the other species over time. However, δ ¹³ C values declined in 3 species, and a lack of change in the δ ¹⁵ N and δ ¹³ C values of forage fish suggests that this change is reflective of a behavioural shift in the distribution of the birds. However, changes in isotopic baselines over the sampling period cannot be ruled out and require further investigation. Our results demonstrate the value of stable isotope analyses of contemporary and archived samples as a cost effective, non-invasive method for monitoring coastal seabirds in a changing world.


Rayner, M. J., Dunphy, B. J., Lukies, K., Adams, N. J., Berg, M., Kozmian-Ledward, L., Pinkerton, M. H., & Bury, S. J. (2021). Stable isotope record from a resident New Zealand seabird community suggests changes in distribution but not trophic position since 1878. Marine Ecology Progress Series, 678, 171-182.


Year-round distribution, activity patterns and habitat use of a poorly studied pelagic seabird, the fluttering shearwater Puffinus gavia 



We present the first study to examine the year-round distribution, activity patterns, and habi- tat use of one of New Zealand’s most common seabirds, the fluttering shearwater (Puffinus gavia). Seven adults from Burgess Island, in the Hauraki Gulf, and one individual from Long Island, in the Marlborough Sounds, were successfully tracked with combined light-saltwater immersion loggers for one to three years. Our tracking data confirms that fluttering shearwa- ters employ different overwintering dispersal strategies, where three out of eight individuals, for at least one of the three years when they were being tracked, crossed the Tasman Sea to forage over coastal waters along eastern Tasmania and southeastern Australia. Resident birds stayed confined to waters of northern and central New Zealand year-round. Although birds frequently foraged over pelagic shelf waters, the majority of tracking locations were found over shallow waters close to the coast. All birds foraged predominantly in daylight and frequently visited the colony at night throughout the year. We found no significant inter-sea- sonal differences in the activity patterns, or between migratory and resident individuals. Although further studies of inter-colony variation in different age groups will be necessary, this study presents novel insights into year-round distribution, activity patterns and habitat use of the fluttering shearwater, which provide valuable baseline information for conserva- tion as well as for further ecological studies. 


Berg M, Linnebjerg JF, Taylor G, Ismar- Rebitz SMH, Bell M, Gaskin CP, et al. (2019) Year- round distribution, activity patterns and habitat use of a poorly studied pelagic seabird, the fluttering shearwater Puffinus gavia. PLoS ONE 14(8): e0219986 



Breeding biology of Fluttering Shearwaters ( Puffinus gavia ) on Burgess Island in northern New Zealand



The Fluttering Shearwater (Puffinus gavia) is an abundant seabird endemic to breeding colonies in northern and central New Zealand. The species remains poorly studied, and here we present the first study to examine its breeding biology in detail. Fluttering Shearwater nests were monitored from laying in September to fledging in January 2016 on Burgess Island in the outer Hauraki Gulf, northern New Zealand. Nine (22%) of forty-one natural nests were located under dense vegetation on the ground. Eggs were laid over a period of 39 days with laying peaking on 12 September. Incubation length was 50.0 ± 3.7 days and chicks fledged after an average of 74.2 ± 4.3 days, from late December to the end of January. Chick growth corresponds to the pattern observed for other Procellariiformes, gaining body mass rapidly to a maximum of 115% of adult mass, and then losing mass until fledging. Chicks were fed most nights throughout chick-rearing. Breeding success was 63.8% and similar to other Puffinus species breeding in pest-free colonies. This study provides baseline biological data for a poorly studied, yet common, New Zealand endemic seabird. The obtained new information will allow for further ecological investigations and improved conservation management.


Berg, M., Linnebjerg, J. F., Ismar, S. M., Gaskin, C. P., & Rayner, M. J. (2017). Breeding biology of fluttering shearwaters (Puffinus gavia) on Burgess Island in Northern New Zealand. Emu-Austral Ornithology, 1-10.​​​​


Using miniaturized radiotelemetry to discover the breeding grounds of the endangered New Zealand Storm Petrel Fregetta maoriana




Identifcation of breeding sites remains a critical step in species conservation, particularly in procellariiform seabirds whose threat status is of global concern. We designed and conducted an integrative radiotelemetry approach to uncover the breeding grounds of the critically endangered New Zealand Storm Petrel Fregetta maoriana (NZSP), a species considered extinct before its rediscovery in 2003. Solar-powered automated radio receivers and hand-held telemetry were used to detect the presence of birds on three island groups in the Hauraki Gulf near Auckland, New Zealand. At least 11 NZSP captured and radiotagged at sea were detected at night near Te Hauturu-o-Toi/Little Barrier Island with the detection of an incubating bird leading to the discovery of the first known breeding site for this species. In total, four NZSP breeding burrows were detected under mature forest canopy and three adult NZSP and two NZSP chicks ringed. Telemetry data indicated NZSP showed strong moonlight avoidance behaviour over the breeding site, had incubation shifts of approximately 5 days and a breeding season extending from February to June/July, a different season from other Procellariiformes in the region. Radiotelemetry, in combination with rigorously collected field data on species distribution, offers a valuable technique for locating breeding grounds of procellariiform seabirds and gaining insights into breeding biology while minimizing disturbance to sensitive species or damage to fragile habitat. Our study suggests an avenue for other breeding ground searches in one of the most threatened avian Orders, and highlights the general need for information on the location of breeding sites and understanding the breeding biology in data-deficient birds.



Rayner, M. J, Gaskin, C.P., Fitzgerald, N.B., Baird, K.A., Berg, M., Boyle, D., Joyce, L., Landers, T.J., Loh, G., Maturin, S., Perrimen, L., Scofield, R.P., Simm, J., Southy, I., Taylor, G.A. Tennyson, A.J.D., Robertson, B.C., Young, M., Walle, R., and Ismar, S.M.H.2015. Using miniaturized radiotelemetry to discover the breeding grounds of the endangered New Zealand Storm Petrel Fregetta maoriana. Ibis, 157(4), pp. 754-766.





An avifaunal survey and conservation assessment of Serranía Sadiri, Madidi National Park, Bolivia 



Durante tres meses de trabajo de campo entre noviembre de 2010 y febrero de 2011, se examinó la avifauna de la serranía Sadiri, departamento La Paz, noroeste de Bolivia. El área alberga bosque seco enano, bosque primario perenne de piedemonte y bosque de llanura tropical, en los yungas bajos del área de endemismo de aves entre Bolivia y Perú. Salvo algunos bosques secos alterados en la parte este de la cresta, el área está en gran parte sin explotar y se encuentra dentro del Parque Nacional Madidi. El estudio cubrió un área de 30 km , con un rango de elevación de 400–1.200 m, pero destacó la zona piedemonte por encima de los 800 m. Presentamos una lista de 274 especies de aves registradas en el área, incluyendo notas de abundancia relativa, rango de altitud, migración y evidencia. Se proporcionan recuentos para especies con registros significativos, incluyendo el primer registro del Vencejo Barbiblanco Cypseloides cryptus y el tercer registro del Vencejo Pechiblanco C. lemosi o Vencejo Negro C. niger en Bolivia. El área protege poblaciones de dos especies vulnerables y tres especies casi amenazadas globalmente, como también cuatro especies de rango restringido. Biogeográficamente, la avifauna de la zona piedemonte incluye un número de especies de crestas periféricas del norte de Bolivia y del sur de Perú, mientras que la zona más baja de la cresta alberga una mezcla de especies características del bosque de llanura tropical. La combinación de alta biodiversidad de aves en un área pequeña y la presencia de poblaciones aparentemente sanas de algunas especies de rango restringido, amenazadas y casi amenazadas le dan a la serranía Sadiri una alta prioridad para la un área de importancia para las aves. 


Berg, M. & Hennessey, B. 2019. An avifaunal survey and conservation assessment of Serranía Sadiri, Madidi National Park, Bolivia. Cotinga, 41:57-71.

Range and status of Green-capped Tanager Tangara meyerdeschauenseei in Bolivia


The Green-capped Tanager Tangara meyerseschauenseei was known until recently only to occur in three sites in southern Peru. Recent field studies in the Apolo area, Department of La Paz, discovered a population in Bolivia. We present 10 observations in a wide area in different habitats, including two in humid cloud forest (Yungas), a habitat that was not known for the species previously. Given the confirmed population in Bolivia, and the addition of another habitat type, its threatened level should change from Vulnerable to Near threatened in the IUCN Red List. In this article we present an update of the area of occurrence of the species in Bolivia based on resent field visit in the Apolo area in La Paz, Bolivia.


Berg, M., Kleunen, A. & Hennessey, B. 2013. Range and status of the Green-capped Tanager Tangara meyderdeschauenseeiin in Bolivia. Cotinga, 36; 52-55.   

Screenshot 2022-09-25 at 21.37.09.png
Screenshot 2022-09-25 at 21.36.53.png
Screenshot 2022-09-25 at 21.33.56.png

Berg et al. 2019

Berg et al. 2017

Rayner et al. 2015

Berg & Hennessey, 2019

Screenshot 2022-09-25 at 21.33.30.png

Berg et al. 2013

bottom of page