Alien Plant Invasions,Introduced Ungulates,and Alternative States in a Mesic Forest in Hawaii

Restoration by natural successional processes after removal of perturbations may not be feasible for many degraded ecosystems. Controlling major ecological threats such as non‐native ungulates is often a critical first step toward restoring native communities but past degradation, interactions with alien species and abiotic features may create conditions requiring additional intervention to ensure effective conservation. We monitored a series of fenced plots within diverse mesic forest on western Kauai in the Hawaiian Islands from 1998 to 2005 to determine the effects of ungulate removal on native and alien plant species. Relative to unfenced control plots, germination of seedlings and frequency of understory species of both native and alien species increased in the fenced plots. Density of both native and alien canopy and understory species declined more in unfenced than fenced plots, but density of native species declined more than alien species density in both fenced and unfenced plots. In fenced plots, the frequency of larger alien woody species and cover of an alien, mat‐forming fern species increased over time, indicating that fencing may encourage alien species that could interfere with regeneration of native species. Our study suggests that effective conservation of this and other remnant native Hawaiian forests will require both ungulate exclusion, removal of alien plant species with especially detrimental effects on native species, and proactive restoration programs for native species without natural sources of propagules. As the effects of invasive species continue to escalate, continental ecosystems lacking high endemism may also require similar interventions to preserve their biodiversity.     

The Potential Influence of a Companion-Animal's Presence on Aspects of the Therapeutic Alliance

ABSTRACT

Seventy-one college students participated in an experiment exploring the impact of a companion-animal's presence (viz., a dog) on several aspects of the participants' experience during an interview. Specifically, the study examined how the presence of a companion animal impacts participants' perception of the interviewer, including perceived levels of empathy and participants' willingness to self-disclose. Participants were prescreened with questions regarding past experience with animals. The researcher then conducted interviews with each participant, simulating a process comparable to that of an abridged initial psychotherapy intake session. Participants completed measures on their experience at the completion of the interview. Primary findings of the study determined that the presence of a companion animal did not influence participants' overall perceptions of the interviewer, willingness to self-disclose to the interviewer, and perceptions of the interviewer's level of empathic understanding. Participants' level of exposure to animals (current and past) also had no impact on these dependent measures. When participants' attitudes toward pets were examined, negative attitudes toward pets were associated with a diminished willingness to self-disclose in this study. This study represents an initial attempt at using more rigorous methodical controls to study the effect of companion animals in therapy-like situations. Contrary to previous research, the results imply that the presence of a companion animal during an interview analogous to the initial psychotherapy intake session may not influence aspects of the therapeutic alliance examined in this study. Future research is needed to determine if the same findings will be found with actual psychotherapy cases.     

Managing the Effects of Introduced Predators on Hawaiian Endangered Seabirds

Introduced predators are one of the greatest threats facing seabirds worldwide. We investigated the effects of multiple introduced predators on 2 endangered seabirds, the Newell's shearwater (Puffinus newelli) and the Hawaiian petrel (Pterodroma sandwichensis), on the island of Kauaʻi, Hawaiʻi, USA. Between 2011 and 2017, we recorded 309 depredations of which 35.6% were by feral cats, 50.2% by black rats (Rattus rattus), 10.4% by pigs (Sus scrofa; feral pigs), and 3.9% by barn owls (Tyto alba). Cats were the most destructive of the predators because they killed more breeding adults than chicks, which had repercussions on breeding probability in following years. Cats and rats were also the most prevalent of all the predators, depredating birds at all of the sites under consideration regardless of how remote or inaccessible. We also considered the effectiveness of predator control over the study period. Reproductive success at all sites increased once predator control operations were in place and depredations by all species except barn owls decreased. Furthermore, we modeled population trajectories for all sites with and without predator control. Without predator control, population trajectories at all sites declined rapidly over 50 years. With predator control operations in place, populations at all sites increased; thus, controlling introduced predators at endangered seabird colonies is important for their management. © 2020 The Wildlife Society.     

Male-immature relationships in multi-male groups of mountain gorillas (Gorilla beringei beringei)

We examined the pattern and possible functions of social interactions between adult males and immatures in three free-ranging, multi-male groups of mountain gorillas (Gorilla beringei beringei). Previous studies conducted during the 1970s when groups contained one to three adult males concluded that male-immature relationships were likely to be a form of low-cost paternal investment [Stewart, Mountain gorillas: three decades of research at Karisoke. Cambridge, UK: Cambridge University Press, 2001]. We evaluated whether this hypothesis still held in groups containing six to nine adult males, or if male-immature relationships might serve other functions (e.g. mating effort, kin selection, or alliance building). Overall, we found that immatures spent the most time near, and interacted most with, the alpha silverback. These behaviors peaked during the period when infants were still quite vulnerable but increasing their independence from their mothers. Such findings suggest that parenting effort remains the primary function of male-immature relationships; however, there is some evidence for the mating effort hypothesis as well.     

Genetic characterization of hybridization between the New Zealand everlastings Helichrysum lanceolatum and Anaphalioides bellidioides (Asteraceae: Gnaphalieae)

Intergeneric hybridization between the endemic New Zealand species Helichrysum lanceolatum and Anaphalioides bellidioides (Asteraceae: Gnaphalieae) at two Banks Peninsula populations was investigated by DNA sequencing and amplified fragment length polymorphism fingerprinting. Crosses in both directions have contributed to the generation of the F1 hybrids, but in the study season hybridization was far more common with H. lanceolatum as the maternal parent. F1 hybrids have reduced, but considerable, fertility and seed collected from them includes back-crosses. Two hybrid plants sampled from the wild appear to be back-crosses to H. lanceolatum. Despite back-crossing, introgression was not demonstrated and is at most limited in scope. These results also corroborate important roles for small population size and rarity in the formation of hybrid lineages in New Zealand's everlastings.  © 2007 Landcare Research New Zealand Ltd. Journal compilation © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 89–98.     

Hawaiian picture‐winged Drosophila exhibit adaptive population divergence along a narrow climatic gradient on Hawaii Island

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Scream-embrace displays in wild black-horned capuchin monkeys

Reintroduction of capuchin monkeys (Cebus apella) into their social group in captivity can elicit sirena screams and embraces. Captive scream-embrace displays are male biased, and females never perform sirena screams. One hypothesis is that scream-embrace displays serve a tension-reduction or reconciliatory function between males with conflicting interests. Alternatively, these displays may function to maintain strong affiliative bonds between friendly male dyads. Scream and/or embrace displays in wild Brazilian black-horned capuchins were analyzed for social and ecological contexts, behavioral components, and individuals involved. Seventy-two displays were observed during the 199-day study period. Among the 66 displays for which both members could be identified by sex, there were 42 occurrences of male-male dyads, 17 of male-female dyads, and seven of female-female dyads. Scream-embrace dyads were male-male pairs significantly more often than expected from group membership, and the alpha male was the only male to engage in scream-embrace displays with females. Female-female pairs did embrace, but never emitted sirena screams. Displays most commonly occurred in "reunion" contexts, primarily the reuniting of subgroups after hours or days out of contact, but also after intergroup encounters, and across groups in "intergroup" displays. Displays were rare, but socially contagious, and subgroup reunions could elicit multiple displays in rapid succession. Although the occurrence of screams and embraces was positively correlated, both behaviors also occurred independently, and their functions may be different. Male sirena screams may be honest advertisements of united alliances, directed toward a third party, whereas the embrace may be a risky affiliative signal, directed primarily within the dyad.     

Richness and species composition of arboreal arthropods affected by nutrients and predators: a press experiment

A longstanding goal for ecologists is to understand the processes that maintain biological diversity in communities, yet few studies have investigated the combined effects of predators and resources on biodiversity in natural ecosystems. We fertilized nutrient limited plots and excluded insectivorous birds in a randomized block design, and examined the impacts on arthropods associated with the dominant tree in the Hawaiian Islands, Metrosideros polymorpha (Myrtaceae). After 33 months, the species load (per foliage mass) of herbivores and carnivores increased with fertilization, but rarified richness (standardized to abundance) did not change. Fertilization depressed species richness of arboreal detritivores, and carnivore richness dropped in caged, unfertilized plots, both because of the increased dominance of common, introduced species with treatments. Herbivore species abundance distributions were more equitable than other trophic levels following treatments, and fertilization added specialized native species without changing relativized species richness. Overall, bird removal and nutrient addition treatments on arthropod richness acted largely independently, but with countervailing influences that obscured distinct top-down and bottom-up effects on different trophic levels. This study demonstrates that species composition, biological invasions, and the individuality of species traits may complicate efforts to predict the interactive effects of resources and predation on species diversity in food webs.     

Adaptive radiation of island plants: evidence from Aeonium (Crassulaceae) of the Canary Islands

The presence of diverse and species-rich plant lineages on oceanic islands is most often associated with adaptive radiation. Here we discuss the possible adaptive significance of some of the most prominent traits in island plants, including woodiness, monocarpy and sexual dimorphisms. Indirect evidence that such traits have been acquired through convergent evolution on islands comes from molecular phylogenies; however, direct evidence of their selective value rarely is obtained. The importance of hybridization in the evolution of island plants is also considered as part of a more general discussion of the mechanisms governing radiations on islands. Most examples are from the Hawaiian and Canarian floras, and in particular from studies on the morphological, ecological and molecular diversification of the genus Aeonium, the largest plant radiation of the Canarian Islands.