Cory’s Shearwater, photograph by Paulo Catry

Alberto Navarro (Marine Ecophysiology Group, Universidad de Las Palmas de Gran Canaria, Canary Islands, Spain) and colleagues have published in the Marine Pollution Bulletin on ingestion of plastics (mainly derived from fishing gear) by Cory's Shearwaters Calonectris borealis and other seabirds.

The paper’s abstract follows:

“Plastic pollution constitutes an environmental problem in the Canary Islands nowadays. Nevertheless, studies evaluating the impact of plastics on its avifauna are still scarce. Gastrointestinal tracts of 88 birds belonging to 14 species were studied for the presence of plastics. Moreover, their livers were analyzed for the determination of bromodiphenyl ethers (BDEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs). Among Cory's shearwaters (n = 45), the frequency of occurrence of plastic ingestion was considerably high (88.89 %). This species had the highest mean value of items (7.22 ± 5.66) and most of them were compatible with lines derived from fishing gear. PCBs and PAHs were detected in all of the samples and OCPs in the great majority of them (98.86 %). Our results highlight the problems that plastic debris (mainly for seabirds) and organic pollutants pose to these species.”

Reference:

Navarro A., Perez Luzardo, O., Gomez, M., Acosta-Dacal, A., Martínez, I., de la Rosa, J.G., Macia-Montes, A., Suarez-Perez, A. & Herrera, A. 2023.  Microplastics ingestion and chemical pollutants in seabirds of Gran Canaria (Canary Islands, Spain).  Marine Pollution Bulletin 186.  doi.org/10.1016/j.marpolbul.2022.114434.

John Cooper, ACAP News Correspondent, 30 December 2022

Motuhara from the air, photograph by Barry Baker

Mike Bell (Toroa Consulting Limited) has produced a final report for the New Zealand’s Department of Conservation via its Conservation Services Programme (CSP), describing results obtained from a visit to the island of Motuhara.  Three ACAP-listed species were studied, including the globally Endangered Northern Royal Albatross Diomedea sanfordi, that will be featured as part of ACAP marking World Albatross Day on 19 June 2023.

The report’s summary follows:

“Northern Royal Albatross (Diomedea sanfordi), Northern Buller’s Mollymawk (Thalassarche bulleri plateri) and Northern Giant Petrel (Macronectes halli) all have significant breeding populations on Motuhara.

Northern Royal Albatross have been counted on Motuhara using aerial photography from 2006, despite uncertainties in censusing a biennial breeding species, it appears the population is in gradual decline, with the current breeding population at 1,400-1,600 pairs annually. A large number of birds are also found breeding on Rangitatahi/The Sisters, where the average count is between 1,700-2,250 breeding pairs between 2017 and 2022. A small population of 30-40 pairs also breeds at Taiaroa Head, Dunedin.

Northern Buller’s Mollymawk have been counted on Motuhara in 2007, 2008 and 2009, with an average count of 14,699 nests (range 14,185-15,238 nests). A repeat ground census in 2016 recorded 17,682 nests with the increase in numbers considered to reflect improved methodology rather than a true increase. This represents the largest breeding colony of the species, with approximately 3,200 pairs also breeding on The Sisters and a small population of 34 pairs on Rosemary Rock, in the Three Kings Motus (northern North Motu).

The number of Northern Giant Petrels breeding on Motuhara has never been systematically counted, but the breeding population was estimated at 2,000 pairs in 1993. Extrapolating from a census during mid chick rearing in 2016 the population of Motuhara was estimated at 1,935 breeding pairs, making Motuhara the largest colony of this species in New Zealand; and the second largest colony globally behind South Georgia.

In January 2021 a field trip to Motuhara was carried out to undertake seabird research. During which GLS devices were deployed on Buller’s Mollymawk, and cameras were set up to record breeding activity at Royal Albatross, Buller’s Mollymawk, and Giant Petrel breeding areas. As it is required to recover devices to obtain the data further trips to the motu were planned in August 2021, and January 2022. Unfortunately, due to the August 2021 Covid-19 lockdown a trip was not possible in August, but one was carried out in January 2022. This report summarises the results of this field trip and summarises research undertaken on Northern Buller’s Mollymawk, Northern Royal Albatross and Northern Giant Petrel; including recovering GLS tracking devices on birds and data from cameras established at colonies.

Reference:

Bell, M.[D.] 2022.  Motuhara Seabird Research: Field Trip Report January 2022.  [Blenheim: Toroa Consulting Limited].  12 pp.

John Cooper, ACAP News Correspondent, 29 December 2021

 
A Black Petrel in the breeding colony on Great Barrier Island, photograph by 'Biz' Bell,Wildlife Management International

The Conservation Services Programme (CSP) of New Zealand’s Department of Conservation works to reduce the impact of commercial fishing on protected species in New Zealand fisheries waters.  Here are summaries of two of its most recent final reports by Wildlife Management International on the ACAP-listed and globally Vulnerable Black Petrel Procellaria parkinsoni by the ecological consultancy Wildlife Management International.

Land component

This report is part of the ongoing study of the tākoketai/black petrel, Procellaria parkinsoni, on Great Barrier Island/Aotea that began in the 1995/1996 breeding season.

During the 2021/2022 breeding season 478 tākoketai/black petrel study burrows were intensively monitored within the Mt Hobson/Hirakimata study area on Aotea/Great Barrier Island.

There were 326 (68.2%) burrows occupied by breeding pairs, 92 (19.2%) occupied by non-breeding birds, and 60 (12.6%) were unoccupied. Overall, 239 chicks were produced from the study burrows representing a fledgling success rate of 73.3%.

Nine census grids were monitored within the study area and accounted for 196 of the inspected study burrows. Of these, 148 were occupied by breeding pairs (75.5%) and 102 chicks were produced representing a fledging success rate of 68.9%. A total of 745 adults and 254 fledgling chicks were captured during the 2021/2022 field season with 107 adults banded this season (including 69 from study burrows). Of the 254 fledgling chicks banded during the 2021/2022 field season, 227 were banded in study burrows; 12 had already fledged prior to the banding visit in May 2022.

There have been a total of 386 returned chicks recaptured at the colony since they were banded prior to fledging. Of these, 124 returned chicks identified during the 2021/2022 breeding season; 23 of which had been caught for the first time at the colony. The majority of returned chicks were from the 2013/2014 breeding season, followed by the 2010/2011 cohort). Not all cohorts were represented as no returned chicks from the 1995/1996 and 1996/1997 cohorts were recaptured this season.

Understanding the factors affecting return rates of chicks within the 35-ha study site is vital. It is important to determine whether it is related to low juvenile survival and/or recruitment or if it is simply due to a lack of detection. Understanding juvenile survival and recruitment is necessary for accurate population estimates and risk assessment modelling. Therefore, it is recommended that effort to obtain this data is completed with urgency.

Preliminary monitoring of pig and other predator occurrence and impact on black petrels on Cooper’s Castle was undertaken this season. Sixteen black petrel burrows were identified within the boundaries of this study area; three were breeding and one was being visited by non-breeding birds. All other burrows were empty. Trail cameras were placed along pig pathways, walking tracks and outside active black petrel burrows. Footage confirmed feral pig, rat, and feral cat presence. While no interactions with black petrels were caught on camera, there was one cat predation and one rat predation at the study colony this season. Introduced species still pose a threat to the black petrel population and it is imperative pest control measures continue.

At-sea captures

n January 2022 WMIL staff were only able to undertake a one-day catching trip out in the waters north-east of the Marotere (Chicken) Islands group, and north of the Mokohinau Islands group. Poor weather prevented a longer trip. A total of 17 black petrels were caught from the back of the boat using a hand cast net and were all un-banded birds. Additional species caught were 18 toanui/flesh[1]footed shearwater (Ardenna carneipes) (Threat Status - At Risk: Relict).

In March 2022 WMIL staff were able to undertake a longer three-day catching trip, targeting the same areas, but particularly north of the Mokohinau Islands group. A total of 130 black petrels were caught from the back of a boat using the same hand cast net method. This total included 5 already banded birds from WMIL study colonies on Aotea/Great Barrier Island and Te Hauturu-o-Toi/Little Barrier Island, as well as 3 banded birds from the at-sea capture work. Additional species caught and banded were 78 flesh-footed shearwater, two New Zealand storm petrel (Fregetta maoriana) (Threat Classification: Nationally Vulnerable) and one rako/Buller’s shearwater (Ardenna bulleri) (Threat Classification: At Risk: Declining).

In November 2022 WMIL staff were able to undertake a two-day catching trip, targeting the same areas as previously. A total of 39 black petrels were caught using the hand cast net method. This total included 2 already banded birds from the WMIL study colony on Aotea/Great Barrier Island. Additionally, 30 flesh-footed shearwaters were also caught and banded, one of which was already banded, having been banded at a WMIL study colony on Lady Alice Island in 2017. Finally one ōi/grey[1]faced petrel (Pterodroma gouldi) (Threat Classification: Not Threatened) was also caught and banded.

Over all trips undertaken by WMIL (April 2021, January 2022, March 2022 and November 2022), a total of 383 seabirds were captured altogether (April 2021: n=67, January 2022: n=35, March 2022: n=211, November 2022: n=70). A total of 176 (January 2022: n=17, March 2022: n=122, November 2022: n=37) black petrels were newly banded over all 2022 trips. Including the April 2021 preliminary trial captures, a total of 241 black petrels have been caught over the cumulative 9 days (April 2021: n=55 over 3 days, January 2022: n=17 on 1 day, March 2022: n=130 over 3 days, November 2022: n=39 over 2 days). Of these, 8 were previously banded at a terrestrial colony, representing 3% of total captures. The average daily capture rate of tākoketai/black petrel for each trip is highly variable; 18 per day in April 2021, 17 per day in January 2022, 43 per day in March 2022, and 20 per day in November 2022, with the average daily capture rate of black petrels for all trips being 27. The highest average catches were in the first and last light periods of the day (7-9am and 5-7pm).

Key recommendations for future work are:

• Trips need to be undertaken towards the start of the breeding season, i.e., mid-November through to early February, with several trips throughout the breeding season to allow WMIL staff to capture more birds.
• A large amount of bait should be taken to facilitate creating more feeding frenzies and theoretically more birds behind the back of the boat for capture.
• Future work should be clarified much further in advance to increase the success of this work particularly dealing with ever changing weather and swell conditions, COVID disruptions, moon phases, and aligning the WMIL team and the skipper’s schedules.
• Undertake future work around the dimmest phases of the moon.
• Undertake work further north with either the same skipper (El Pescador Charters) or another suitable vessel (i.e., with a duckboard), to target other areas of this species range.
• Future work should budget for a team of three (minimum) to have flexible flying and accommodation costs, as well as the rising costs of diesel fuel for boat charters and covering the cost of higher bait use.

References:

Bell, E.A., Welch, M. & Lamb, S. 2022.  Key demographic parameters and population trends of tākoketai/black petrels (Procellaria parkinsoni) on Aotea/Great Barrier Island: 2021/2022.  POP2021-01 final report prepared by Wildlife Management International for the Department of Conservation, Wellington.  35 pp.

Burgin, D. 2022.  Summary report for at-sea capture work for tākoketai/black petrels 2022.  POP2021-01 final report prepared by Wildlife Management International for the Department of Conservation, Wellington.  18 pp.

Both reports are available from here.

John Cooper, ACAP News Correspondent, 28 December 2022

Scopoli’s Shearwater, photograph by Georgios Karris

Virginia Morera-Pujol (Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona, Spain) and colleagues have published in the open-access journal Diversity and Distributions on challenges using individual tracking data to infer higher-level distributions.  The authors used a data set of 1346 year-round migratory trips from 805 individuals of Cory’s Calonectris borealis, Cape Verde C. edwardsii and Scopoli’s C. diomedea Shearwaters breeding in 34 colonies in the Mediterranean Sea and the Atlantic Ocean, spanning 10 years, to address the issue.

The paper’s abstract follows:

"Aim

Over the last decades, the study of movement through tracking data has grown exceeding the expectations of movement ecologists. This has posed new challenges, specifically when using individual tracking data to infer higher-level distributions (e.g. population and species). Sources of variability such as individual site fidelity (ISF), environmental stochasticity over time, and space-use variability across species ranges must be considered, and their effects identified and corrected, to produce accurate estimates of spatial distribution using tracking data.

Innovation

We developed R functions to detect the effect of these sources of variability in the distribution of animal groups when inferred from individual tracking data. These procedures demonstrated our procedures with simulated datasets and showed their applicability on a real-world dataset containing 1346 year-round migratory trips from 805 individuals of three closely related seabird species breeding in 34 colonies in the Mediterranean Sea and the Atlantic Ocean, spanning 10 years. We detected an effect of ISF in one of the colonies, but no effect of the environmental stochasticity on the distribution of birds for any of the species. We also identified among-colony variability in nonbreeding space use for one species, with significant effects of population size and longitude.

Main conclusions

This work provides a useful, much-needed tool for researchers using animal tracking data to model species distributions or establish conservation measures. This methodology may be applied in studies using individual tracking data to accurately infer the distribution of a population or species and support the delineation of important areas for conservation based on tracking data. This step, designed to precede any analysis, has become increasingly relevant with the proliferation of studies using large tracking datasets that has accompanied the globalization process in science driving collaborations and tracking data sharing initiatives.”

With thanks to Georgios Karris.

Reference:

Morera-Pujol, V., Catry, P., Magalhãe, M., Péron, C., Reyes-González, J.M., Granadeiro, J.P., Militão, T., Dias, M.P., Oro, F., Dell'Omo, G., Müller, M., Paiva, V.H., Metzger, B., Neves, V., Navarro, J., Karris, G., Xirouchakis, S., Cecere, J.G., Zamora-López, A., Forero, M.G., Ouni, R., Romdhane, M.S., De Felipe, F., Zajková, Z., Cruz-Flores, M., Grémillet, D., González-Solís, J. & Ramos, R. 2022.  Methods to detect spatial biases in tracking studies caused by differential representativeness of individuals, populations and time.  Diversity and Distribution. doi.org/10.1111/ddi.13642.

John Cooper, ACAP News Correspondent, 27 December 2022