A House Mouse on Marion Island, photograph by Ben Dilley

Luke Gierus (Robinson Research Institute, University of Adelaide, Australia) and colleagues have published open access in the Proceedings of the National Academy of Sciences (PNAS) on developing a genetic biocontrol strategy to control House Mice Mus musculus.  Although the paper suggests from modelling that eradication of mice in an island situation could be achieved by utilizing a ‘gene drive’ that spreads through a population and makes females infertile, the technique has yet to be tested outside the laboratory in field trials.

ACAP Latest News reached out to Anton Wolfaardt, Project Manager of the Mouse-Free Marion Project on the possibility of using such a strategy to eradicate the albatross-killing mice of South Africa’s sub-Antarctic Marion Island.

Anton writes in reply: “There are still quite a few hurdles to overcome before this is a tool that could be considered a possible option.  The first is a technical one, currently being investigated by research – does it work and what are the potential consequences?  The second and perhaps more challenging hurdle is a regulatory one – most governments don’t currently have regulatory frameworks that are equipped to deal with such a tool, and there are considerable ethical issues that regulators would need to consider.  There is no guarantee if and when this may be shown to work, and when it may be approved for use, hence - for our current planning to eradicate mice from Marion Island - our focus is on methods that are already proven and are currently available.  We cannot afford to wait for an as-yet unproven methodology with no certain timeframe around when it might become available.”

So, while a new method to eradicate mice would be an addition to counter the impacts of invasive mice on islands, it seems that efforts to eradicate Marion’s mice, and those on other seabird islands, such as the USA’s Midway Atoll next year, will continue to use the “tried and tested” method of aerial dispersion of a rodenticide-laced cereal bait.  This has shown to be successful in eradicating mice on a number of sub-Antarctic islands, including Enderby and Antipodes off New Zealand, Australia’s Macquarie and South Georgia (Islas Georgias del Sur)* in the South Atlantic.

The paper’s abstract follows:

“Invasive rodents are a major cause of environmental damage and biodiversity loss, particularly on islands.  Unlike insects, genetic biocontrol strategies including population-suppressing gene drives with biased inheritance have not been developed in mice.  Here, we demonstrate a gene drive strategy (t_CRISPR) that leverages super-Mendelian transmission of the t haplotype to spread inactivating mutations in a haplosufficient female fertility gene (Prl).  Using spatially explicit individual-based in silico modeling, we show that t_CRISPR can eradicate island populations under a range of realistic field-based parameter values.   We also engineer transgenic t_CRISPR mice that, crucially, exhibit biased transmission of the modified t haplotype and Prl mutations at levels our modeling predicts would be sufficient for eradication.  This is an example of a feasible gene drive system for invasive alien rodent population control.”

Read a New Scientist article on the publication.

Reference:

Gierus, L., Birand, A., Bunting, M.D., Godahewa, G.I., Piltz, S.G., Oh, K.P., Piaggio, A.J., Threadgill, D.W., Godwin, J., Edwards, O., Cassey, P., Ross, J.V., Prowse, T.A.A. & Thomas, P.Q. 2022.  Leveraging a natural murine meiotic drive to suppress invasive populations.  PNAS doi.org/10.1073/pnas.22133081

*A dispute exists between the Governments of Argentina and the United Kingdom of Great Britain and Northern Ireland concerning sovereignty over the Falkland Islands (Islas Malvinas), South Georgia and the South Sandwich Islands (Islas Georgias del Sur y Islas Sandwich del Sur) and the surrounding maritime areas.

John Cooper, ACAP News Correspondent, 21 November 2022

An image of a typhoon with the eye clearly visible in the centre. Some adult Streaked Shearwaters fitted with GPS trackers have been shown to fly into the eye of a storm rather than skirt its perimeter

A study by Emmanouil Lempidakis (Department of Biosciences, Swansea University, United Kingdom) and colleagues published in the journal PNAS (Proceedings of the National Academy of Sciences) has found some adult shearwaters fly into the eye of a storm to lower the risk of wrecking.

The paper’s abstract as follows:

“Cyclones can cause mass mortality of seabirds, sometimes wrecking thousands of individuals. The few studies to track pelagic seabirds during cyclones show they tend to circumnavigate the strongest winds. We tracked adult shearwaters in the Sea of Japan over 11 y and found that the response to cyclones varied according to the wind speed and direction. In strong winds, birds that were sandwiched between the storm and mainland Japan flew away from land and toward the eye of the storm, flying within ≤30 km of the eye and tracking it for up to 8 h. This exposed shearwaters to some of the highest wind speeds near the eye wall (≤21 m s^–1) but enabled them to avoid strong onshore winds in the storm’s wake. Extreme winds may therefore become a threat when an inability to compensate for drift could lead to forced landings and collisions. Birds may need to know where land is in order to avoid it. This provides additional selective pressure for a map sense and could explain why juvenile shearwaters, which lack a map sense, instead navigating using a compass heading, are susceptible to being wrecked. We suggest that the ability to respond to storms is influenced by both flight and navigational capacities. This may become increasingly pertinent due to changes in extreme weather patterns.”

Reference:

Lempidakis, E., Shephard, E.L.C., Ross, A.N., Matsumoto, S., Koyama, S., Takeuchi, I. & Yoda, K. (2022).  Pelagic seabirds reduce risk by flying into the eye of the storm. PNAS 119 (41) e2212925119. https://doi.org/10.1073/pnas.22129251

A White-chinned Petrel; photograph by Richard Phillips from the Bristish Antarctic Survey (BAS)

Lily K. Bentley (Department of Zoology, University of Cambridge, UK) and colleagues have published open access in the journal IBIS on the differing foraging habitat preferences between the Grey Petrel Procellaria cinerea and White-chinned Petrel P. aequinoctialis from colonies on Gough Island and Bird Island (South Georgia*).

The paper’s abstract follows:

“Foraging niche specialisation is thought to occur when different members of speciose communities divide resources in either time or space. Here we compared habitat preferences of the congeneric Grey Petrel Procellaria cinerea and White-chinned Petrel P. aequinoctialis, tracked in the same calendar year using GPS loggers from Gough Island and Bird Island (South Georgia), respectively. We identified periods of active foraging and determined habitat characteristics using remote-sensing data. Although these highly pelagic species could potentially overlap at sea across large areas, they showed markedly different foraging preferences during their incubation periods, which are temporally offset because Grey Petrels breed during the austral winter. Grey Petrels foraged mostly in pelagic cold-water areas to the north-west of South Georgia, whereas White-chinned Petrels foraged almost exclusively in the warm, shallow waters of the Patagonian Shelf. Within each species, foraging habitat characteristics were highly consistent. Our results demonstrate the diversity of habitat preferences within genera, and provide further evidence that colony-specific information on habitat preference is crucial to identify important feeding areas for pelagic predators.”

Reference:

Bentley, L.K., Manica, A., Dilley, B.J., Ryan, P.G. and Phillips, R.A. (2022), Divergent foraging habitat preferences between summer-breeding and winter-breeding Procellaria petrels. Ibis. Accepted Author Manuscript. https://doi.org/10.1111/ibi.13152

*A dispute exists between the Governments of Argentina and the United Kingdom of Great Britain and Northern Ireland concerning sovereignty over the Falkland Islands (Islas Malvinas), South Georgia and the South Sandwich Islands (Islas Georgias del Sur y Islas Sandwich del Sur) and the surrounding maritime areas.

A colour-banded Northern Royal Albatross rises over its egg at Taiaroa Head in November 2016

Four recently laid eggs of the globally Endangered and nationally Vulnerable Northern Royal Albatross Diomedea sanfordi are suspected to have been stolen from the mainland colony at Taiaroa Head/Pukekura on the Otago Peninsula, South Island, New Zealand (click here).  The eggs were noticed missing on 10 November during routine checks by Department of Conservation (DOC) rangers, who have been left feeling “devastated”.  It is thought the eggs may have been taken as there are no signs they were eaten by predators.  DOC compliance officers and police are investigating.

The colony is a fenced nature reserve, with entry by permit only.  Northern Royal Albatrosses are protected under the Wildlife Act 1953 and it is an offence to kill, injure, harass or disturb them (including their eggs).  It is reported that the affected parents have all been given dummy eggs to incubate in case they will be needed as foster parents.  This is a normal management technique in the colony for birds that lose their own eggs.

In a New Zealand Herald article on the incident, Lyndon Perriman, who worked as a ranger at Taiaroa Head between 1989 and 2016, said there had been no such occurrences during this time there.  He thought it unlikely that a pest predator was responsible: “Stoats, ferrets or cats... they certainly couldn’t take away an albatross egg without breaking it.”   The supposed theft has now prompted a review of security at the site, Lyndon noting there was a gap in the fence.

It seems the only previous incident of stealing eggs at Taiaroa Head was in the very early days in the 1930s when eggs were taken each year prior to Lance Richdale protecting the solitary breeding pair until its chick fledged (click here).  For albatrosses (which usually breed on non-inhabited islands) a somewhat similar case occurred with 15 breeding Laysan Albatrosses Phoebastria immutabilis being killed and their eggs smashed by juvenile vandals within the fenced colony in the Kaena Point Natural Area Reserve on the Hawaiian island of Oahu.  This incident led to a successful prosecution (click here).  ACAP Latest News will report if the Taiaroa Head egg loss results in anything similar.

The orphan Northern Royal Albatross close to fledging, photograph by Laura Findlay

Related news is that the 2021/22 breeding season resulted in 25 Northern Royal Albatross chicks fledging from Taiaroa Head, out of 36 eggs laid, giving an overall breeding success of 69.4%.  The first to fledge was the live-streaming Royal Cam’s Lilibet, named after the childhood nickname of the late Queen Elizabeth II; the last to fledge left on 10 September.  An orphaned chick fledged over 2/3 October.  Since its foster parents went missing in April, it had been hand fed over 111 kg of fish, squid and octopus.

The 2022/23 season’s Royal Cam pair will be chosen near the end of November once all of the new season’s eggs have been laid.  Prior to the egg napping, it was hoped over 40 eggs would be laid.  As of 9 November, 23 eggs have been counted, with 135 returning colour-banded adults recorded.

The Northern Royal Albatross is one of two albatross species chosen to be featured for next year’s World Albatross Day on 19 June with its theme of “Plastic Pollution”.  Posters and an infographic sponsored by the New Zealand Department of Conservation featuring the bird will be produced next year for “WAD2023” in ACAP’s three official languages of English, French and Spanish.

John Cooper, ACAP News Correspondent, 17 November 2022