Mistletoe in Eucalypt Forest—A Resource for Birds

Abstract

The incidence of mistletoe plants on eucalypt trees in dry sclerophyll forest was recorded in Eden Forestry Region, New South Wales. Before logging there were 210 trees per hectare over 10 ems diameter breast height. On average 2.8 trees per hectare carried mistletoe at the rate of S.O mistletoe plants per hectare. In similar forest logged to 91 trees per hectare there remained 1.8 trees per ha carrying 2.3 mistletoe plants per ha. Yertchuk, Eucalyptus cansideniona, Maiden, was the most common tree and had the most mistletoe plants in the study area with an average of 1.7 plants per tree. Birds foraging in mistletoe flowers were compared with birds foraging in eucalypt blossom to determine the use of these resources. Out of 180 plots 41 individuals were recorded as foraging in mistletoe while only eleven birds were recorded feeding amongst blossom of Eucalyptus sieberi L. Johnson. Logging reduced the number of trees per ha and therefore of mistletoe plants per ha and the number of bird foraging activity in approximately the same proportion. Birds acknowledged as common to abundant were involved in this foraging data.

Do bird species richness and community structure vary with mistletoe flowering and fruiting in Western Australia?

“…Importantly, the patterns of presence of fruit did not coincide across our survey sites (maximum 100 km apart), and yet the presence of bird species was associated with site-specific timing of the presence of fruit. Therefore, although we are not able to discount entirely ecosystem-wide effects such as the detectability of birds (Field et al 2002), spring and winter migration (see review on partial migration by Chan 2001) and surges driven by rainfall that attract locally mobile species (as well as promoting recruitment and fruiting of mistletoes ;Reid 1987;Yan and Reid 1995), the findings of the present study are consistent with those of previous studies that have observed a positive link between increased species richness and density of mistletoes (Turner 1991;Bennetts et al 1996), and manipulative studies comparing the avifauna of two adjacent woodland remnants, one of which had been manually cleared of mistletoe (Watson 2002;Watson and Herring 2012). Reid (1986) reported that mistletoe is one of the few reliable sources of fruit in eucalypt forests of south-eastern Australia, and although we only recorded fruiting phenology over 1 year, anecdotal observations (K. Napier, pers.…”

“…Despite their importance as a food resource, there have been few studies examining how mistletoes may influence changes in Australian avian communities (see studies by Turner 1991;Watson 2002;Watson et al 2011;Watson and Herring 2012). Additionally, we have very little information on the fruiting and flowering phenology of mistletoes in south-western WA.…”

“…; whistlers, Pachycephala spp.) also use clumps of mistletoe as a foraging substrate, as mistletoes often have abundant and distinctive insect assemblages (Turner 1991;Watson 2001;Start 2011;Watson 2011), although Burns et al (2011) found no difference in insect assemblages between mistletoe clumps and surrounding vegetation. Mistletoes therefore reliably provide important food and shelter resources for hundreds of fauna species, providing resources and ecosystem services out of proportion to their abundance and contribution to biomass (Davidson et al 1989;Watson 2001Watson , 2002Mathiasen et al 2008;Watson and Herring 2012).…”

“…Keast 1958;Reid 1987;Turner 1991;Brown et al 1997), many species of mistletoe also have extended flowering and fruiting phenologies that minimise competition with other plant species but which are also important for sustaining populations of their avian pollinators and dispersers. Australian mistletoes continually draw upon the water and nutrient resources of their host and can thus flower and set fruit during dry seasons when little other nectar or fruit is available in the landscape (Paton and Ford 1977;Reid 1986;Watson 2001).…”

“…Loranthaceous mistletoes provide birds with important nectar and fruit resources (Kuijt 1969;Calder 1983;Davidar 1985;Reid 1986;Ladley et al 1997;Robertson et al 1999), with at least 50 bird species, including several species of honeyeater, recorded consuming mistletoe nectar or fruit in Australia (Keast 1958;Reid 1987;Turner 1991;Brown et al 1997). With two exceptions, the root-parasitic Western Australian Christmas Tree (Nuytsia floribunda) and Atkinsonia (Atkinsonia ligustrina) (Hawkeswood 1981;Watson 2011), all Australian loranthaceous mistletoes are pollinated by birds.…”