Nesting innovations allow population growth in an invasive population of rose-ringed parakeets

Certain traits of recipient environments, such as the availability of limiting resources, strongly determine the establishment success and spread of non-native species. These limitations may be overcome through behavioral plasticity, allowing them to exploit alternative resources. Here, we show how a secondary cavity nester bird, the rose-ringed parakeet Psittacula krameri, innovates its nesting behavior as a response to the shortage of tree cavities for nesting in its invasive range in Tenerife (Canary Islands). We observed that some breeding pairs excavated their own nest cavities in palms, thus becoming primary cavity nester, whereas others occupied nests built with wood sticks by another invasive species, the monk parakeet Myiopsitta monachus. The use of these novel nesting strategies increased the number of breeding pairs by up to 52% over 6 years, contributing to a 128.8% increase of the whole population. Innovative nests were located at greater heights above ground and were more aggregated around conspecifics but did not result in greater breeding success than natural cavities. Occupation of monk parakeet colonies by rose-ringed parakeets also benefited the former species through a protective-nesting association against nest predators. Our results show how an invasive species innovate nesting behaviors and increase nest-site availability in the recipient environment, thus facilitating its population growth and invasion process. Potential behavioral innovations in other invasive rose-ringed parakeet populations may be overlooked, and should be considered for effective management plans.

Six-Legged Livestock

This chapter relates the history of the well-known Western honey bees Apis mellifera, just one of 20,000 species of bees. It relates how honey bees originated in Asia, where they nested in tree cavities, from which humans robbed honey. Beekeeping arose as a mutualistic relationship, providing shelter for bees in exchange for consistent access to their products and was prominent in ancient Egypt, from where the practice moved to Western Asia and Europe. Honey bees were taken to North America in 1622 by colonists needing pollinators of food crops. The chapter explains the major roles honey bees play as pollinators of crops, enabling a diversity of food in modern diets and providing billions of dollars in economic benefit. Uniting flowering plants with pollinators means we raise honey bees as six-legged livestock, manipulating and moving the bees to meet human needs. Honey bees face modern threats, and threats to bees are threats to our food supply.

Influence of Forest Management and Sylvicultural Treatments on Abundance of Snags and Tree Cavities in Mountain Mixed Beech Forests

In this study the influence of forest management on the characteristics of snags and tree cavities in the Hyrcanian forests of Iran was investigated. In particular, the effect of two sylvicultural treatments (shelter wood and single-tree selection) was assessed in comparison to protected stands. The abundance, diameter, height, and degree of decay of snag species, and the characteristics of birds excavated and natural cavities (number and height from the ground level) were measured by systematic plots in each stand. The results showed that the abundance, species diversity, and size of snags in both of the sylvicultural treatments were significantly lower than the protected stands. The number of birds excavated and natural cavities on thicker snags with moderate decay was significantly higher than other decay classes. Abundance, species diversity, size of snags, and number of tree cavities in the single-tree selection stands were significantly higher than sheltered-wood stands.

Acorn storage in tree cavities by Eurasian jay (Garrulus glandarius L.)

Seed hoarding by granivorous animals requires cache-protection strategies which allow to protect hoarded seeds against pilferage. This study reports the first case of acorn hoarding in tree cavities by Eurasian Jays (Garrulus glandarius). Out of 116 removed acorns of both pedunculate oak (Quercus robur) and Northern red oak (Q. rubra), we localized 14 consumed and 102 stored acorns. Five experimental acorns (4.9% of stored acorns) were found stored in tree cavities. The notion that hoarding seeds in tree cavities may constitute a cache-protection behavior of Eurasian Jays represents a working hypothesis that ought to be tested in future studies.

Comparative nesting patterns and success of Mynas and Starlings (Aves: Sturnidae) inhabiting Jahangirnagar University campus, Bangladesh

Nesting patterns of four species of mynas and starlings, Common Myna (Acridotheres tristis), Jungle Myna (Acridotheres fuscus), the Asian-pied Starling (Gracupica contra) and Chestnut-tailed Mtarling (Sturnia malabarica) were studied in Jahangirnagar University campus from March to September in 2016. Nests were searched systematically throughout the study area and nesting parameters like nest dimensions, nest-site selection, tree species preference, nesting materials, clutch size and nesting success were examined. A total of 101 nests were recorded where 31 nests were of Common Myna, 10 of Jungle Myna, 49 of the Asian-pied Starling and 11 nests were of Chestnut-tailed Starling. Overall, the sturnids preferred nesting on trees (n=84) to anthropogenic structures (n=17). Common myna showed maximum variation in nest-site selection using tree holes (n=12), tree branches (n=10) and building cornices, holes or crevices (n=9) whereas Chestnut-tailed Starling nested only in tree cavities (n=11). Jungle Myna built nests both in tree holes (n=4) and in building holes and crevices (n=6). The Asian-pied Starlings built their domed nests mostly on tree branches (n=47) where 69% nests were peripheral and 31% were central in position. Out of 20 species of trees utilized for nesting purpose, the majority of nests were built on Whites iris Albizia procera (n=18) followed by Neem Azadirachta indica (n=10) and Mahogany Swietenia mahagoni (n=10). The nests were constructed between 2 and 18m (8±3.8m) from the ground level. Among 19 types of nesting materials recorded, twigs, leaves, straws, grasses, feathers, plastics and polythene were frequently used by all four species while the Asian-pied starling used more rubbish materials than other species. Highest nesting success (80%) was recorded in Common Myna whereas the Asian-pied Starling, Chestnut-tailed Starling and Jungle Myna had 77.8%, 75% and 66.7% of nesting success respectively. Adaptions to using different nesting sites in Common Myna and comparatively higher nesting height in the Asian-pied Starling may have facilitated the greater nesting success. Bangladesh J. Zool. 48(2): 321-334, 2020

NEST BOX USE AND POLYGYNY IN AN ENDANGERED PRIMATE SPECIES: THE BLACK LION TAMARIN (LEONTOPITHECUS CHRYSOPYGUS)

The black lion tamarin, Leontopithecus chrysopygus, is an endemic and endangered primate species from the Atlantic Forest of the interior of São Paulo State, Brazil. Its mating system is characterized as monogamous and females give birth to two twin infants during each breeding season. They are known to mainly sleep in tree holes, which is considered as a pertinent strategy for increasing their protection from predators during the night. Artificial cavities, like nest boxes, have been installed for other species in areas where tree cavities are depleted, in order to replace them. In this study, we report (i) the use of nest boxes in the wild by a group of black lion tamarins and (ii) the first record of polygyny for this species.

The common noctule bat (Nyctalus noctula): population trends from artificial roosts and the effect of biotic and abiotic parameters on the probability of occupation

As urbanization and intense forestry management are increasing, natural bat roosting opportunities, e.g. tree cavities, are constantly declining. A common management practice, especially in urban environments, is the installation of bat boxes. We assessed (1) abundance trends inside artificial bat boxes of the noctule bat (Nyctalus noctula) over 11 years in Neu-Ulm, Germany, and identified (2) parameters affecting the occupation rate. Further, we compared (3) abundance of noctule bats in bat boxes between areas with large availability of natural roosts (forests) and urban areas with primarily artificial roosting structures (parks). Our results revealed a severe decline of noctule bats over 11 years. Further, our results indicate that bat boxes cannot fully replace natural tree cavities. Nonetheless, they support roost availability in areas already altered and providing only low amounts of natural bat roosts. The findings of our study have important implications for the conservation of bats in urbanized landscapes and underline the importance of old and intact forests for local biodiversity.

Overlapping den tree selection by three declining arboreal mammal species in an Australian tropical savanna

Tree cavities are important denning sites for many arboreal mammals. Knowledge of cavity requirements of individual species, as well as potential den overlap among species, is integral to their conservation. In Australia’s tropical savannas, development of tree cavities is enhanced by high termite activity, and, conversely, reduced by frequent fires. However, it is poorly understood how the availability of tree cavities in the tropical savannas impacts tree cavity use and selection by cavity-dependent fauna. There has been a severe decline among arboreal mammal species in northern Australia over recent decades. Investigation of their cavity requirements may illuminate why these species have declined drastically in some areas but are persisting in others. Here we examined this issue in three species of arboreal mammals (Trichosurus vulpecula, Mesembriomys gouldii, Conilurus penicillatus) on Melville Island, northern Australia. We radiotracked individuals to their den sites to evaluate whether the species differ in their den tree and tree-cavity selection. The strongest influence on den tree selection was the presence of large cavities (> 10 cm entrance diameter), with all three species using larger cavities most frequently. Conilurus penicillatus, the smallest species, differed the most from the other species: it frequently was found in smaller, dead trees and its den sites were closer to the ground, including in hollow logs. The two larger species had broader den tree use, using larger live trees and dens higher up in the canopy. Dens of C. penicillatus are likely to be more susceptible to predation and destruction by high-intensity savanna fires. This may have contributed to this species’ rapid decline, both on Melville Island and on the mainland. However, the apparent preference for larger tree cavities by all three arboreal species is concerning due to the limited availability of large trees across Australian savannas, which are subject to frequent, high-intensity fires.