Breeding System and Response of the Pollinator to Floral Larceny and Florivory Define the Reproductive Success in Aerides odorata

Consumption of pollination reward by felonious means in a plant species can influence the foraging behavior of its pollinator and eventually the reproductive success. So far, studies on this aspect are largely confined to interaction involving plant-pollinators and nectar robbers or thieves. However, a foraging guild in such interactions may also include floral herbivores or florivores. There is a paucity of information on the extent to which nectar larcenists may influence the foraging behavior of the pollinator and reproductive fitness of plants in the presence of a florivore. We investigated various forms of larceny in the natural populations of Aerides odorata, a pollinator-dependent and nectar-rewarding orchid. These populations differed in types of foraging guild, the extent of larceny (thieving/robbing), which can occur with or without florivory, and natural fruit-set pattern. The nectariferous spur of the flower serves as an organ of interest among the foraging insects. While florivory marked by excision of nectary dissuades the pollinator, nectar thieving and robbing significantly enhance visits of the pollinator and fruit-set. Experimental pollinations showed that the species is a preferential outbreeder and experiences inbreeding depression from selfing. Reproductive fitness of the orchid species varies significantly with the extent of floral larceny. Although nectar thieving or robbing is beneficial in this self-compatible species, the negative effects of florivory were stronger. Our findings suggest that net reproductive fitness in the affected plant species is determined by the overarching effect of its breeding system on the overall interacting framework of the foraging guild.

The importance of grassland patches and their associated rainforest ecotones to insectivorous bats in a fire-managed tropical landscape

ContextEcotones are recognised globally as areas of high biodiversity, yet relatively little is known about how fauna use different types of ecotone. Tropical rainforest–grassland ecotones are shaped through particular fire regimes, creating both gradual and abrupt ecotones. Insectivorous bats contribute considerably to mammalian diversity, and their capacity for flight allows them to use ecotones in a three-dimensional way, making them an informative faunal group for evaluating ecotone use. AimsTo critically evaluate how insectivorous bats use gradual and abrupt ecotones between rainforest and grassland habitats. MethodsBat detectors were placed every 50m, along 200-m transects, through five gradual and five abrupt rainforest–grassland ecotones. The activity of all insectivorous bats, as well as open, edge–open and closed foraging guilds (defined by echolocation call type), was compared among grassland and rainforest habitats, gradual and abrupt ecotones and positions across the ecotones. Key resultsMean total bat activity, mean open and edge–open foraging guild activity were significantly higher in grassland positions, followed by the edge, and were lowest in the rainforest. Closed foraging guild bats showed no preference for either habitats, but had significantly higher activity in gradual compared with abrupt ecotones. Mean activity of edge–open foraging guild bats was affected strongly by the interaction between ecotone type and position along the ecotone. Gradual ecotones had a more even proportion of all three bat foraging guilds along the ecotone compared with abrupt ecotones. Most of these findings were likely driven by the structural complexity of gradual ecotones that fulfilled microhabitat requirements for all three foraging guilds, but may also have been influenced by insect prey abundance. ConclusionsThe present study demonstrated the importance of grassland patches in a tropical, rainforest landscape, and of gradual rainforest–grassland ecotones for insectivorous bats. Gradual ecotones promote complex habitat mosaics to allow closed foraging guild species to take advantage of food resources provided by grasslands, and provide all bats proximity to potential roosting and foraging sites. ImplicationsThe data clearly suggest that a suitable fire regime should be used to maintain current grassland patches within a rainforest landscape, and to promote gradual ecotones for use by insectivorous bats.

Effect of Multiple Adjoining Habitats on Avifaunal Diversity in an Agriculture-Based Wetland Adjacent to the Hooghly River, West Bengal, India

Sau M., Chakraborty M., Das R. and Mukherjee S. 2018. Effect of multiple adjoining habitats on avifaunal diversity in an agriculture based-wetland adjacent to the Hooghly River, West Bengal, India. Ring 40: 59-92. This study was conducted on four plots having a cluster of different combinations of forest, wetland, and agricultural land, as well as a single marshland habitat near the river Hooghly. We obtained 17,817 counts for 150 species in 32 days of year-round sampling. The wetland-agricultural land associated with forest had the highest species diversity (132 species, Shannon ̄H – 1.63), heterogeneity (Shannon J’ – 0.773), and number of unique species (33 species), and the lowest dominance (Simpson Index 1/D – 39.35), in contrast with the marsh, which had the lowest diversity (41 species, Shannon ̄H – 1.39), highest homogeneity (Shannon J’ – 0.863), and a lack of uniqueness. The plot with secondary forest patches between an agricultural field and human settlements showed the highest species dominance (Simpsons Diversity 1/D – 17.465). Species rarity ranged from 68.2% to 77.6% within the area under study. There were 25 species common to all plots, which formed six distinct groups based on their abundance. Carnivores were found to be the dominant foraging guild throughout the habitats. Thirty-two per cent of the species are migratory, with the families Scolopacidae and Motacillidae predominating. The Jaccard and Sorensen indices reveal the greatest species similarity between the wetlandpisciculture plot and the marshland. These indices together with the hierarchical cluster analysis indicate the uniqueness of the plot of open forest habitat adjoining the wetland, which offers the best living conditions for migratory species. Our study concludes that when a wetland is surrounded by agriculture rather than fisheries, avifaunal diversity increases, whereas forest-associated wetland-farmland maximizes species richness with minimum dominance and hence imparts greater stability to the overall community structure.

KOMUNITAS AVIFAUNA DI SEPANJANG ALIRAN ANAK SUNGAI WAILAWA DESA TAWIRI KECAMATAN TELUK AMBON, KOTA AMBON

The study was conducted in April 2017, located along the Wailawa watercourses, Tawiri Village, Ambon. The method applied in these studies were Point Count, while data analysis using Shannon-Wiener Diversity Index, Evenness Index, Domination Index, Similarity Index, and Guild Composition. The results showed that the number of bird species found along Wailawa watercourse were 28 species of 25 genera, 17 families, and 8 orders. The diversity of bird species is moderate (H ‘= 2,54). The bird species similarity analysis resulted in three bird communities, including: (1) bird communities in mangrove forest, estuaries with grass vegetation, (2) bird communities in garden and settlement habitats, and (3) bird communities in mixed forest habitat. Mangrove forest and estuaries have the highest species similarities (0,63). Estuaries and mix gardens have the lowest bird similarities (0,05). Bird communities in mangrove forests and estuaries are heterogeneous because they have more species with a more equitable distribution of species abundance, while in other habitat, their are homogenous because of relatively have a low species diversity with uneven distribution of species abundance.Penelitian ini bertujuan menganalisis komunitas burung, meliputi kekayaan jenis, keanekaragaman jenis, kelimpahan relatif, kemerataan jenis, foraging guild, serta kesamaan jenis. Penelitian dilakukan pada bulan April 2017, berlokasi di sepanjang Anak Sungai Wailawa, Desa Tawiri, Kota Ambon. Metode pengambilan data adalah metode point count, sedangkan analisis data menggunakan Indeks Keanekaragaman Shannon-Wiener, Indeks Kemerataan Jenis Evennes, Indeks Dominasi Jenis, Indeks Kesamaan Jenis, dan Foraging guild. Hasil penelitian menunjukkan jumlah jenis burung yang ditemukan sebanyak 28 jenis dari 25 genus, 17 famili, dan 8 ordo. Keanekaragaman jenis burung tergolong sedang (H’ = 2,54). Hasil analisis tingkat kesamaan komunitas menghasilkan tiga komunitas burung, meliputi : (1) komunitas burung di hutan mangrove-muara sungai bervegetasi rumput, (2) komunitas burung di kebun dan permukiman, serta (3) komunitas burung di kebun campur. Hutan mangrove dan muara sungai memiliki kesamaan jenis burung tertinggi, yakni 0,63. Muara sungai dan kebun campur memiliki kesamaan jenis burung terendah, yakni 0,05. Komunitas burung di hutan mangrove dan muara sungai adalah komunitas heterogen karena memiliki lebih banyak spesies dengan distribusi kelimpahan spesies yang lebih merata, sedangkan komunitas burung pada tipe habitat lainnya adalah komunitas homogen karena keragaman jenis relatif rendah dan distribusi kelimpahan spesies tidak merata.

Seasonal changes in acoustic detection of forest birds

Autonomous recording is commonly used to examine the structure of avian communities in a variety of landscapes. Many birds return to the breeding grounds in May yet acoustic surveys typically begin in June. In many species, singing activity declines through the breeding season and so detections may be lower later in the season. The aim of our study was to compare the species richness and the community composition measured early (mid-late May) and later (mid-late June) in the breeding season. We recorded the community of singing birds at 13 locations in York Region, Ontario, Canada woodlots over two days using autonomous recorders. We used spectrographic analysis to scan recordings and identify all vocalizing species. We found that species richness was significantly higher in early recordings compared to later recordings with detections of both migrants and residents displaying this trend. Most food and foraging guilds were also detected significantly less often later in the season. Despite changes in species richness, the proportion of the community represented by each foraging guild did not vary between early and late recordings. Our results suggest that acoustic recordings could be collected earlier in the breeding season, extending the survey period into May. If the primary goal of monitoring is to document species presence/absence then earlier recordings may be advantageous.