Tracking Changes of Hidden Food: Spatial Pattern Learning in Two Macaw Species

Food availability may vary spatially and temporally within an environment. Efficiency in locating alternative food sources using spatial information (e.g., distribution patterns) may vary according to a species’ diet and habitat specialisation. Hypothetically, more generalist species would learn faster than more specialist species due to being more explorative when changes occur. We tested this hypothesis in two closely related macaw species, differing in their degree of diet and habitat specialisation; the more generalist Great Green Macaw and the more specialist Blue-throated Macaw. We examined their spatial pattern learning performance under predictable temporal and spatial change, using a ‘poke box’ that contained hidden food placed within wells. Each week, the rewarded wells formed two patterns (A and B), which were changed on a mid-week schedule. We found that the two patterns varied in their difficulty. We also found that the more generalist Great Green Macaws took fewer trials to learn the easier pattern and made more mean correct responses in the difficult pattern than the more specialist Blue-throated Macaws, thus supporting our hypothesis. The better learning performance of the Great Green Macaws may be explained by more exploration and trading-off accuracy for speed. These results suggest how variation in diet and habitat specialisation may relate to a species’ ability to adapt to spatial variation in food availability.

Missing for almost 100 years: the rare and potentially threatened bee, Pharohylaeus lactiferus (Hymenoptera, Colletidae)

The Australian endemic bee, Pharohylaeus lactiferus (Colletidae: Hylaeinae) is a rare species that requires conservation assessment. Prior to this study, the last published record of this bee species was from 1923 in Queensland, and nothing was known of its biology. Hence, I aimed to locate extant populations, provide biological information and undertake exploratory analyses relevant to its assessment. Pharohylaeus lactiferus was recently rediscovered as a result of extensive sampling of 225 general and 20 targeted sampling sites across New South Wales and Queensland. Collections indicate possible floral and habitat specialisation with specimens only found near Tropical or Sub-Tropical Rainforest and only visiting Stenocarpus sinuatus (Proteaceae) and Brachychiton acerifolius (Malvaceae), to the exclusion of other available floral resources. Three populations were found by sampling bees visiting these plant species along much of the Australian east coast, suggesting population isolation. GIS analyses used to explore habitat destruction in the Wet Tropics and Central Mackay Coast bioregions indicate susceptibility of Queensland rainforests and P. lactiferus populations to bushfires, particularly in the context of a fragmented landscape. Highly fragmented habitat and potential host specialisation might explain the rarity of P. lactiferus. Targeted sampling and demographic analyses are likely required to thoroughly assess the status of this species and others like it.

Species Composition and Ecological Distribution of the Subfamily Cicindelinae Latreille, 1801 (Coleoptera: Carabidae) Based on Voucher Specimens in Sarawak

The subfamily Cicindelinae which belongs to the family Carabidae are commonly known as tiger beetles. Despite the recent studies conducted on this taxon, current ecological knowledge on tiger beetles is limited. Thus, this study aimed to provide a current checklist of tiger beetles as well as their species distribution, abundances and habitat preferences in Sarawak based on voucher specimens from Universiti Malaysia Sarawak Insect Reference Collection (UIRC). A total of 76 specimens of tiger beetles were examined in which comprising of seven genera from eight species. The genus Neocollyris was represented with two species, namely Neocollyris (s. str.) ermaginata and Neocollyris (Stenocollyris) sarawakensis macrodera, while the other genera were represented by only one species, respectively. The most abundant species with 64 individuals (84.21%) were represented by Cosmodela aurulenta, followed by Abroscelis tenuipes araneipes and Therates labiatus with three individuals (3.95%) and N. ermaginata with two individuals (2.63%). In this study, there were eight ecological habitats being identified, namely heath forest, limestone forest, littoral forest, mixed dipterocarp forest, oil palm plantation, peat swamp forest, riverine forest and urban area. The data indicates that C. aurulenta being recorded at seven ecological habitats suggesting this species to have a wide distribution capability while species such as A. tenuipes araneipes, Callytron doriai, Cicindela sp., Myriochila (s. str.) specularis brevipennis, N. ermaginata and N. s. macrodera suggesting these species to have a very narrow habitat specialisation. The results of this preliminary study provide evidence on the need to conduct further studies on the ecological aspects of tiger beetles in Sarawak. Keywords: Cicindelinae, ecological distribution, Sarawak, tiger beetles, voucher specimens

Increasing connectivity enhances habitat specialists but simplifies plant–insect food webs

Strong declines of grassland species diversity in small and isolated grassland patches have been observed at local and landscape scales. Here, we study how plant–herbivore interaction webs and habitat specialisation of leafhopper communities change with the size of calcareous grassland fragments and landscape connectivity. We surveyed leafhoppers and plants on 14 small (0.1–0.6 ha) and 14 large (1.2–8.8 ha) semi-natural calcareous grassland fragments in Central Germany, differing in isolation from other calcareous grasslands and in the percentage of arable land in the surrounding landscape (from simple to complex landscapes). We quantified weighted trophic links between plants and their phytophagous leafhoppers for each grassland fragment. We found that large and well-connected grassland fragments harboured a high portion of specialist leafhopper species, which in turn yielded low interaction diversity and simple plant-leafhopper food webs. In contrast, small and well-connected fragments exhibited high levels of generalism, leading to higher interaction diversity. In conclusion, food web complexity appeared to be a poor indicator for the management of insect diversity, as it is driven by specialist species, which require high connectivity of large fragments in complex landscapes. We conclude that habitat specialists should be prioritized since generalist species associated with small fragments are also widespread in the surrounding landscape matrix.