Is the breeding behaviour of nesting seabirds influenced by the presence of a predatory reptile—the tuatara?

Abstract

Increasing our knowledge of the costs and benefits associated with commensal interactions is necessary both for a better understanding of how ecological communities are structured and for determining conservation actions. We investigated the concomitant use of a burrow by a nesting seabird, the fairy prion (Pachyptila turtur), and a medium-sized predatory reptile, the tuatara (Sphenodon punctatus). Arrival time of fairy prions at the burrow each night was found to be delayed by the presence of a tuatara at the burrow. Use of the burrow by tuatara almost halved the time fairy prions spent at the burrow with their chick. The effect of this cohabitation on each species can be expected to change over both space and time, i.e. with changes in population densities and season. Hence it is possible that in newly established colonies of birds with low numbers in the presence of tuatara, tuatara predation may have a deleterious impact.

Contrasting responses of lizard occurrences to burrowing by a critically endangered seabird

“…Previous research has consistently highlighted that lizard habitat selection is influenced by the need to avoid harsh and/or fluctuating environmental temperatures (Downes and Shine 1998, Milne et al 2003, Du et al 2006, Andersson et al 2010, Jewell 2017. To thermoregulate, ectotherms such as lizards, can exhibit a behaviour known as 'shuttling', whereby they utilise thermal shelters periodically throughout the day to maintain stable internal temperatures (Milne et al 2003, Andersson et al 2010, Corkery et al 2015, Jewell 2017. We thus suggest that Diving Petrel burrows facilitate 'shuttling' behaviour in Stewart Island green skinks (and to a certain extent, southern grass skinks), allowing them to shelter from the extreme temperature maxima that are common within dune systems (Fischer et al 2018a).…”

“…Whenua Hou Diving Petrels are the only seabird species in New Zealand that breeds en masse in dune systems (Fischer et al 2017a(Fischer et al ,b, 2018a. Aside from the likely biophysical and biochemical ecosystem services provided by Whenua Hou Diving Petrels across dune systems (e.g., nutrient cycling, bioturbation, seed dispersal; Ellis 2005, Orwin et al 2016, Otero et al 2018, Whenua Hou Diving Petrels may increase the habitat suitability for skinks (Milne et al 2003, Corkery et al 2015. Therefore, this 'Critically Endangered' species might be a crucial ecosystem engineer within its specific habitat type.…”

“…As an exception, the large and enigmatic tuatara (Sphenodon punctatus) has been shown to benefit from co-habiting fairy prion (Pachyptila turtur) burrows. Tuatara benefitted from warmer internal temperatures when inhabiting prion burrows and fed on prion chicks (Corkery et al 2014(Corkery et al , 2015. In addition, lizard communities (Scincidae and Diplodactylidae) were found to be more abundant and diverse on islands inhabited by seabirds than seabird-free islands (Markwell and Daugherty 2002).…”

“…Both are listed as listed as "At Risk -Declining" in New Zealand following considerable range reductions caused by predation by invasive predators and habitat destruction (Hitchmough et al 2016, Jewell 2017. Based on the studies conducted on tuatara (Corkery et al 2014(Corkery et al , 2015, we hypothesised that the two threatened small lizard species in the dune of Codfish Island would occur more frequently at sites with Whenua Hou Diving Petrel burrows than at sites without. To test our hypothesis, we used a large number of repeat surveys and occupancy modelling to account for imperfect detection of both skink species.…”

Assessing the suitability of non-invasive methods to monitorinterspecific interactions and breeding biology of the South Georgian diving petrel (Pelecanoides georgicus)

“…Furthermore, interspecific interactions, other than predation by introduced species, can impact seabird populations (Gummer et al 2015). Various cases of negative interactions with native species have been documented, including morepork (Ninox novaeseelandiae) and tuatara (Sphenodon punctatus) predation (Trainor 2008;Corkery et al 2015), non-predatory attacks on petrel chicks by Campbell Island teal (Anas nesiotis) (R. Sagar pers. comm.…”