Disturbed Amazonian forests support diminished breeding bird communities

The Condor ◽  
2021 ◽  
Author(s):  
Cameron L Rutt ◽  
Michael D Kaller ◽  
Philip C Stouffer
Keyword(s):  
Forest Type ◽  
Secondary Forest ◽  
Breeding Habitat ◽  
Species Flock ◽  
Occupancy Models ◽  
Ecological Value ◽  
Mixed Species ◽  
Presence Data ◽  
Undisturbed Forest ◽  
Amazonian Forests

Abstract Twenty percent of the Brazilian Amazon has now been deforested, and deforestation rates are increasing. This compels us to evaluate the conservation potential of human-modified landscapes; yet the ecological value of regenerating and fragmented Amazonian forests remains poorly understood. To date, most faunal studies in disturbed forests have examined metrics derived from presence or abundance. Although valuable, these data cannot tell us how old-growth species are using disturbed forests. In this study, we complement presence data with breeding observations to assess more comprehensively the habitat quality of disturbed forests in central Amazonia. We synthesized breeding evidence from standardized passive mist-netting, mixed-species flock-following, and opportunistic nest-searching across a full annual cycle in 30–35-year-old secondary forest, 10-ha fragments, and undisturbed forest. We then used multistate occupancy models to estimate the number of undetected breeding species in each forest type, which illustrated that fewer species bred in secondary forest (–43%) and 10-ha fragments (–17%) than in undisturbed forest. Both these losses are larger than the associated decrease in species richness alone (–17% and –10%, respectively). Notably, we confirmed breeding by only three terrestrial and near-ground insectivores in fragments and secondary forest combined (of the 9 species found in undisturbed forest). Disturbed forests also supported fewer breeding individuals (–35% to –50%) and, in secondary forest, fewer successful breeding attempts (–24%). Encouragingly, however, some forest-dependent birds are breeding and producing fledglings in disturbed forests, including representatives from almost every guild. This was especially apparent for mixed-species flocks and army-ant followers, two guilds that have historically been considered vulnerable to anthropogenic disturbance. Therefore, despite a loss of breeding habitat in disturbed forests, these data suggest that landscapes composed of regenerating forest and small fragments have conservation potential for forest bird populations.

scholarly journals Is Intestinal Bacterial Diversity Enhanced by Trans-Species Spread in the Mixed-Species Flock of Hooded Crane (Grus monacha) and Bean Goose (Anser fabalis) Wintering in the Lower and Middle Yangtze River Floodplain?

Animals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 233
Author(s):  
Zhuqing Yang ◽  
Lizhi Zhou
Keyword(s):  
Contact Time ◽  
Alpha Diversity ◽  
Gut Bacteria ◽  
Species Flock ◽  
Mixed Species ◽  
Microbial Composition ◽  
Indirect Contact ◽  
Hooded Crane ◽  
Bean Goose ◽  
Intestinal Pathogens

Diversity of gut microbes is influenced by many aspects, including the host internal factors and even direct or indirect contact with other birds, which is particularly important for mixed-species wintering waterbird flocks. In this study, Illumina high-throughput sequencing was used to analyze the intestinal bacteria of the hooded crane and bean goose whose niches overlap at Shengjin Lake. We tested whether contact time enhances the trans-species spread of gut bacteria. Results indicate alpha-diversity and microbial composition displayed significant separation between the two hosts in every wintering period, although the number of bacteria types shared increased with increasing contact time. For the same species, with the lengthening of contact time, alpha-diversity and the number of operational taxonomic units (OTUs) in the host intestine augmented, and the common OTUs and structural similarity of microflora in the middle and late periods were more than in the early and middle periods. In addition, we found a very high proportion of shared pathogens. Our results indicate that, although intestinal microflora of different species were separated, direct or indirect contact in the mixed-species flock caused the spread of gut bacteria trans-species, indicating that more attention should be paid to intestinal pathogens in wild birds.

scholarly journals The snake community of Serra do Mendanha, in Rio de Janeiro State, southeastern Brazil: composition, abundance, richness and diversity in areas with different conservation degrees

2009 ◽  
Vol 69 (3) ◽  
pp. 795-804 ◽  
Author(s):  
JAL. Pontes ◽  
RC. Pontes ◽  
CFD. Rocha
Keyword(s):  
Rio De Janeiro ◽  
Secondary Forest ◽  
Southeastern Brazil ◽  
Future Research ◽  
Native Forest ◽  
Abundance Distribution ◽  
Forested Areas ◽  
Undisturbed Forest ◽  
Banana Plantations ◽  
Janeiro State

We studied and compared parameters of the snake community of the Serra do Mendanha, Rio de Janeiro State, southeastern Brazil (22º 48'-22º 51' S and 43º 31'-43º 28' W), such as: abundance distribution, richness, species diversity and biomass, between forested areas, areas under regeneration and agriculture areas (banana plantations); to obtain information about the natural history and facilitate the development of future research. For capturing the snakes we used: pitfall traps, drift-fences and visual search (diurnal and nocturnal) along four transects for each habitat. The captured snakes were measured with a tape and caliper, weighed with dynamometers and sexed with the use of a catheter. The animals marked (with ventral scales cut) were released for posterior recapture. One individual per species was fixed and deposited at the Museu Nacional, Rio de Janeiro. We undertook an effort of 840 man/hour, and captured a total of 207 snakes belonging to 25 species (Colubridae 80.2%, Elapidae 12.6%, Viperidae 6.3% and Boidae 0.9%). The most abundant were: Liophis miliaris (n = 33), Micrurus corallinus and Chironius fuscus (both with n = 26); the least abundant: Elapomorphus quinquelineatus, Siphlophis compressus and Tropidodryas serra (all with n = 1). The species that contributed the greatest biomass were Spilotes pullatus (7,925 g), Chironius laevicollis (4,694 g), Liophis miliaris (3,675 g) and Pseustes sulphureus (3,050 g); those that contributed the lowest biomass were: Siphlophis compressus, Tropidodryas serra (both with 4 g) and Elapomorphus quinquelineatus (3 g). We found significant differences between the sampled habitats at the Serra do Mendanha (undisturbed forest, secondary forest and banana plantations). The results showed that a great reduction in the abundance, richness, diversity and biomass of the snakes occurs when the native forest is replaced by banana plantations.

scholarly journals A model for the importance of large arborescent palms in the dynamics of seasonally-dry amazonian forests

2005 ◽  
Vol 5 (2) ◽  
pp. 151-156 ◽  
Author(s):  
Rodolfo Salm ◽  
Euphly Jalles-Filho ◽  
Cynthia Schuck-Paim
Keyword(s):  
Forest Regeneration ◽  
Forest Canopy ◽  
Forest Succession ◽  
Secondary Forest ◽  
Forest Disturbance ◽  
Dry Forest ◽  
Forest Patch ◽  
Seasonally Dry ◽  
Palm Trees ◽  
Amazonian Forests

In this study we propose a model that represents the importance of large arborescent palms in the dynamics of seasonally-dry Amazonian forests. Specifically, the model is aimed at guiding the investigation of the role of large arborescent palms on forest regeneration and succession. Following disturbance, the high level of luminosity reaching recently formed forest gaps favors the quick proliferation of shade-intolerant lianas that, by casting shade on the crowns of mature forest trees and increasing tree-fall probability, suppress forest succession. Due to their columnar architecture palm trees are, however, not severely affected by vines. As the palms grow, the canopy at the gaps becomes gradually higher and denser, progressively obstructing the passage of light, thus hindering the growth of shade-intolerant lianas and enabling late-successional tree development and forest regeneration. Owing to the long time associated with forest regeneration, the model cannot be tested directly, but aspects of it were examined with field data collected at an Attalea maripa-rich secondary forest patch within a matrix of well-preserved seasonally-dry forest in the Southeastern Amazon. The results indicate that (1) forest disturbance is important for the recruitment of large arborescent palms species, (2) these palms can grow rapidly after an event of disturbance, restoring forest canopy height and density, and (3) secondary forest dominated by palm trees species may be floristically similar to nearby undisturbed forests, supporting the hypothesis that the former has undergone regeneration, as purported in the model.

Context-specific behavior serves as a mechanism of interspecific cohesion in mixed-species flocks

The Auk ◽  
2021 ◽  
Author(s):  
Sean M Williams ◽  
Catherine A Lindell
Keyword(s):  
Flight Distance ◽  
Species Flock ◽  
Mixed Species ◽  
Specific Behavior ◽  
Call Type ◽  
Interspecific Associations ◽  
Mixed Species Flocks ◽  
Context Specific ◽  
Species Flocks

Abstract We investigated whether context-specific behavior is responsible for the cohesion of mixed-species flocks of antshrikes and antwrens in Amazonian Peru. Antshrikes perform a behavior while spatially repositioning, to which antwrens respond by approaching. The cohesion of interspecific associations requires communication, although the mechanisms often are unexplored. In monospecific groups, cohesion among individuals is maintained with actions or vocalizations given in a certain context. Dusky-throated Antshrikes (Thamnomanes ardesiacus) vocalize while in flight and the number of times they vocalize covaries with the flight distance. We refer to this pairing of flight and vocalization as repositioning behavior. Furthermore, antshrikes pair a different call type with perching, which we refer to as perching behavior. We followed Long-winged (Myrmotherula longipennis) and White-flanked Antwrens (M. axillaris) and recorded their response following natural vocalizations (no playback used) given by the antshrikes. Long-winged Antwrens, but not White-flanked, flew toward an antshrike significantly sooner and were more likely to approach the antshrikes after the repositioning behavior than after perching behavior. In addition, Long-winged Antwrens, but not White-flanked, flew toward an antshrike sooner after a longer series of repositioning calls than after a shorter series. We did not distinguish between the Long-winged Antwrens’ response as a function of movement vs. vocalizations of the antshrikes, although we argue that vocalizations are likely a more important communication component of repositioning behavior than movement. It remains unclear whether the antshrikes are deliberately signaling the Long-winged Antwrens or the antwrens are taking advantage of the repositioning behavior; active signaling is possible since antshrikes benefit from antwrens. White-flanked Antwrens may be less responsive to the antshrikes since they have a lower propensity to occur in a mixed-species flock. The results indicate that the repositioning behavior of Dusky-throated Antshrikes is a key mechanism of interspecific cohesion of Amazonian mixed-species flocks of the understory.

scholarly journals Mixed Species Flock, Nest Height, and Elevation Partially Explain Avian Haemoparasite Prevalence in Colombia

PLoS ONE ◽  
2014 ◽  
Vol 9 (6) ◽  
pp. e100695 ◽  
Author(s):  
Angie D. González ◽  
Nubia E. Matta ◽  
Vincenzo A. Ellis ◽  
Eliot T. Miller ◽  
Robert E. Ricklefs ◽  
...  
Keyword(s):  
Species Flock ◽  
Mixed Species ◽  
Nest Height

Dissecting biomass dynamics in a large Amazonian forest plot

2009 ◽  
Vol 25 (5) ◽  
pp. 473-482 ◽  
Author(s):  
Renato Valencia ◽  
Richard Condit ◽  
Helene C. Muller-Landau ◽  
Consuelo Hernandez ◽  
Hugo Navarrete
Keyword(s):  
Secondary Forest ◽  
Forest Plot ◽  
Human Intervention ◽  
Terra Firme ◽  
Natural Habitats ◽  
Forest Patch ◽  
Amazonian Forest ◽  
Large Trees ◽  
Amazonian Forests ◽  
Tierra Firme

Abstract:Above-ground biomass (AGB) is increasing in most of the Amazon forests. One hypothesis is that forests are responding to widespread and intense human intervention prior to the European conquest (>500 y ago). In this study we confront this hypothesis with changes in AGB over 6.3 y in a large western Amazonian forest plot (>150 000 shrubs and trees and 1100 species with dbh ≥ 10 mm in 25 ha). We examined AGB flux in different habitats and across diameter classes. The forest lost small stems (4.6%), gained large trees (2.6%), and gained biomass (0.7%). The change in AGB stock was due entirely to this upward shift in size leading to more canopy trees and fewer saplings after just 6 y. Across habitats, the biggest increment in biomass was in the secondary-forest patch (3.4% y−1) which we know was cleared about 27 y ago, whereas mature forest on ridges and valleys had small increases (0.10% and 0.09% y−1, respectively). In both censuses, AGB stocks were >50% higher on the ridge than in the valley while relative growth and mortality were higher in the valley. Mean wood specific gravity (WSG) decreased with increasing diameter class; WSG did not change much between censuses in mature forests and did not contribute to the change in AGB stocks. Our forest increased its standing biomass, but far less than the average reported for other Amazonian forests (i.e. 0.30 vs. 0.98 Mg ha−1 y−1). We find no evidence to support the notion that this forest is recovering from long-past human intervention. Instead of a long-term recovery, we believe the forest changed in response to natural fluctuations of the environment (e.g. changes in precipitation, higher CO2), windstorms or other more recent events. The significant differences in AGB stocks between valley and ridge suggest that the terra firme forests are a mosaic of natural habitats, and that this mosaic is in part responsible for the variation in biomass stocks detected in Amazonian terra firme forests.Resumen: La biomasa aérea de la mayoría de los bosques amazónicos está incrementando. Una hipótesis es que los bosques están respondiendo a un disturbio humano intenso y ampliamente distribuido, anterior a la llegada de los conquistadores europeos (>500 años atrás). En este estudio se confronta esta hipótesis con los cambios en biomasa encontrados en 6.3 años en una parcela de gran escala de la Amazonia occidental (>150.000 arbustos y árboles con diámetro a la altura del pecho ≥10 mm y 1100 especies en 25 ha). Los resultados se examinan por categorías de diámetro y hábitat. En este período el bosque perdió tallos pequeños (4.6%), ganó árboles grandes (2.6%) y ganó biomasa (0.7%). La ganancia en biomasa fue debida enteramente al incremento de árboles de gran tamaño que significó más árboles de dosel y menos juveniles en apenas 6 años. Entre los hábitats, el mayor incremento en biomasa se encontró en un parche de bosque secundario de colina (3.4%/año), cuya edad es de 27 años, mientras el bosque maduro de las colinas y los valles incrementó escasamente (0.10% y 0.09%/año, respectivamente). Tanto al inicio como al final del estudio, el stock de biomasa fue >50% más grande en la colina que en el valle mientras que el crecimiento y la mortalidad relativa fueron mayores en el valle. La media de la gravedad específica de la madera (GEM) fue menor a mayor clase diamétrica; en el bosque maduro, el cambio en la GEM fue insignificante y no contribuyó al aumento en stocks de biomasa. El bosque incrementó la biomasa aérea pero mucho menos que el promedio reportado para otros bosques amazónicos (i.e. 0.30 vs. 0.98 Mg ha−1/año). No se encontró evidencia que apoye la noción de que el bosque se está recuperando de un disturbio de gran escala ocurrido en el pasado. En su lugar, se cree que el bosque cambió en respuesta a fluctuaciones naturales del ambiente (e.g. cambios en precipitación, mayor concentración de CO2), vendavales u otro tipo de eventos más recientes. La diferencia significativa en los stocks de biomasa encontrada entre el valle y la colina sugiere que la tierra firme es un mosaico de hábitats naturales y que este mosaico podría explicar en parte la variación encontrada en los stocks de biomasa de bosques amazónicos de tierra firme.

Structure, dynamics, home range and activity pattern of mixed-species bird flocks in a montane alder-dominated secondary forest in Ecuador

1996 ◽  
Vol 12 (3) ◽  
pp. 333-343 ◽  
Author(s):  
Bent Otto Poulsen
Keyword(s):  
Home Range ◽  
High Altitude ◽  
Activity Pattern ◽  
Secondary Forest ◽  
Individual Identification ◽  
Home Ranges ◽  
Mixed Species ◽  
Structure Dynamics ◽  
The Andes ◽  
Mixed Species Flocks

ABSTRACTTwo mixed-species bird flocks were studied in a high-altitude humid secondary forest in the Andes of Ecuador. Birds were mist-netted and colour-ringed for individual identification. The flocks (A and B) were followed to record structure, dynamics, home range and activity pattern. All observations of the two flocks studied included members from all vertical levels, which is different from flocks of Amazonia. In two nucleus species, some individuals alternated between the flocks, a feature not previously reported. Various tanagers were loosely associated, joining and leaving flocks. Minimum home-range sizes of flocks A and B were 4.2 ha and 7.8 ha, respectively. Some individuals of two species used an area encompassing the home ranges of both flocks. Mean flock sizes in A and B were 21.7 and 44.7 individuals, whereas the mean numbers of species were 13.7 and 21.7, respectively. Number of species and individuals were high compared to even most lowland flocks. Altogether, mixed-species flocks in different habitats and at various latitudinal and altitudinal sites appear to have some features in common, but others are highly distinct. Compared to the great stability of Amazonian flocks, some high-altitude flocks of secondary forest in the Andes appear to be more dynamic and unstable.

scholarly journals Structure and Dynamics of Mixed-Species Flocks in a Hawaiian Rain Forest

The Auk ◽  
2003 ◽  
Vol 120 (1) ◽  
pp. 82-95
Author(s):  
Patrick J. Hart ◽  
Leonard A. Freed
Keyword(s):  
Rain Forest ◽  
High Variability ◽  
Species Flock ◽  
Flock Size ◽  
Mixed Species ◽  
Individual Level ◽  
Interspecific Associations ◽  
Nuclear Species ◽  
Mixed Species Flocks ◽  
Species Flocks

Abstract Mixed-species flocks of native and introduced birds were studied for four years in an upper elevation Hawaiian rain forest. Those flocks were characterized by strong seasonality, large size, low species richness, high intraspecific abundance, a lack of migrants, and a general lack of territoriality or any sort of dominance hierarchy. There was high variability among years in patterns of occurrence at the species level, and high variability within years at the individual level. These flocks are loosely structured social groupings with apparently open membership. The fluid, unstable movement patterns, high degree of variability in size and composition, and lack of positive interspecific associations are not consistent with the “foraging enhancement” hypothesis for flocking. Two resident, endangered insectivores, the Akepa (Loxops coccineus) and Hawaii Creeper (Oreomystis mana) served as “nuclear” species. Flock composition was compared between two study sites that differed significantly in density of these two nuclear species. Flock size was similar at the two sites, primarily because the nuclear species were over-represented relative to their density. This observation suggests that birds are attempting to achieve a more optimal flock size at the lower density site.

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