Fragmentation in eucalypt woodlands promotes nest‐tree occupancy by a despotic species, the noisy miner (Manorina melanocephala)

Abstract

The effects of habitat fragmentation as a threat to biodiversity are well known; decreased connectivity can potentially influence population processes and dynamics, resulting in smaller, isolated populations that may not function optimally. However, fragmentation may also increase the amount of edge or ecotone habitat available to open country species, benefiting their populations and enabling them to dominate remnant habitats. Noisy miners (Manorina melanocephala) are one such species, occupying eastern‐Australian eucalypt woodlands. They are considered a ‘despotic’ species, in that their presence negatively impacts woodland avifauna biodiversity due to their aggressive exclusion of other taxa from occupied areas. Despite this well‐known impact, little information exists on the patterns of nest‐tree occupancy by noisy miners within eucalypt woodlands. In the current study, we explored the patterns of nest‐tree occupancy by noisy miners across two successive years, aiming to identify preferences for breeding areas relative to vegetation structure. Our results show that both habitat fragmentation and the characteristics of individual eucalypt trees in an area influenced nest‐tree occupancy. Noisy miners constructed nests in trees near the edge of woodland patches more often than expected. Moreover, the nest tree chosen was a eucalypt that was significantly smaller than randomly selected trees from the surrounding area. The results highlight the importance of habitat management measures that may reduce the suitability of woodland patches as nesting sites for this species, in order to mitigate the severe effects of this despotic edge specialist.

Nestlings reduce their predation risk by attending to predator-information encoded within conspecific alarm calls

“…Fieldwork was conducted in the 2015 breeding season from mid-September to late October. To find nests, we surveyed study sites every 2–3 days for signs of nesting activity from mid-August when nesting activities normally commence at these colonies 27 . Once nest sites were located, they were marked with small numbered cattle ear tags (Allflex, Australia) attached to a nearby tree.…”

“…acoustically different calls that elicit different anti-predator behaviour responses in adult birds) intraspecific alarm calls in comparison to familiar interspecific alarm calls. Noisy miners are an Australian honeyeater with open cup nest that is often predated by a range of predators 26 , 27 . Noisy miners further possess a complex acoustic repertoire 28 and produce two functionally referential alarm calls for different predatory types 20 : (1) Aerial alarm calls, which include a series of high-pitched, up-slurred whistles (Fig.…”

The complex acoustic repertoire of a highly social species, the Noisy Miner,Manorina melanocephala

“…Recordings were carried out over a 6-month period (April-September 2013) that overlaps with the prebreeding period through to the beginning of nesting (early August; Barati et al 2016). Each site was visited an average of five times per week, with visits averaging 4 h (total visits: 120; total recording hours: 480).…”

“…Each site was visited an average of five times per week, with visits averaging 4 h (total visits: 120; total recording hours: 480). Birds were banded at both sites with a unique combination of three coloured bands and an aluminium band (see Barati et al 2016 for details), allowing individual recognition to be achieved through the use of binoculars (Monarch 7, 10 × 42, Nikon, Japan). All vocalisations emitted by individuals were recorded from a distance of up to 15 m by J. H., at 48 kHz with 16-bit accuracy through the use of a portable Professional Solid State Recorder (Marantz PMD661, Japan) and a Sennheiser shotgun microphone (ME67, USA), protected by a fur windshield (Rycote Softie, UK).…”

Morphometric and physiological development confirm skull ossification level as a reliable indicator of age in a passerine bird, the Noisy Miner

“…The range of the Noisy Miner is characterised by both population expansion and density increases, with accompanying negative impacts on ecological communities (Maron 2007). This is because Noisy Miners both benefit from human-induced landscape changes in the eucalyptdominated habitats of this region, such as increased habitat fragmentation (Barati et al 2016), but also their complex mobbing system that aggressively excludes competitors from areas that they occupy (Arnold 2000). Removal via direct culling has been considered as the preferred management and control practice for this species (Melton et al 2021).…”