Prey-capture benefits in a mixed-species group of Amazonian tamarins, Saguinus fuscicollis and S. mystax

1992 ◽  
Vol 31 (5) ◽  
Author(s):  
CarlosA. Peres
Keyword(s):  
Prey Capture ◽  
Species Group ◽  
Mixed Species ◽  
Saguinus Fuscicollis

scholarly journals Individuals from different-looking animal species may group together to confuse shared predators: simulations with artificial neural networks

2006 ◽  
Vol 274 (1611) ◽  
pp. 827-832 ◽  
Author(s):  
Colin R Tosh ◽  
Andrew L Jackson ◽  
Graeme D Ruxton
Keyword(s):  
Animal Species ◽  
Empirical Work ◽  
Species Group ◽  
Mixed Species ◽  
Retinotopic Maps ◽  
Species Groups ◽  
Artificial Neural ◽  
Mixed Species Groups ◽  
Species Grouping ◽  
Prey Items

Individuals of many quite distantly related animal species find each other attractive and stay together for long periods in groups. We present a mechanism for mixed-species grouping in which individuals from different-looking prey species come together because the appearance of the mixed-species group is visually confusing to shared predators. Using an artificial neural network model of retinotopic mapping in predators, we train networks on random projections of single- and mixed-species prey groups and then test the ability of networks to reconstruct individual prey items from mixed-species groups in a retinotopic map. Over the majority of parameter space, cryptic prey items benefit from association with conspicuous prey because this particular visual combination worsens predator targeting of cryptic individuals. However, this benefit is not mutual as conspicuous prey tends to be targeted most poorly when in same-species groups. Many real mixed-species groups show the asymmetry in willingness to initiate and maintain the relationship predicted by our study. The agreement of model predictions with published empirical work, the efficacy of our modelling approach in previous studies, and the taxonomic ubiquity of retinotopic maps indicate that we may have uncovered an important, generic selective agent in the evolution of mixed-species grouping.

Leaders of progressions in wild mixed-species troops of saddleback (Saguinus fuscicollis) and mustached tamarins (S. mystax), with emphasis on color vision and sex

2003 ◽  
Vol 61 (4) ◽  
pp. 145-157 ◽  
Author(s):  
Andrew C. Smith ◽  
Hannah M. Buchanan-Smith ◽  
Alison K. Surridge ◽  
Nicholas I. Mundy
Keyword(s):  
Color Vision ◽  
Mixed Species ◽  
Saguinus Fuscicollis

scholarly journals Mixed-species associations of Diana and Campbell's monkeys: the costs and benefits of a forest phenomenon

Behaviour ◽  
2003 ◽  
Vol 140 (3) ◽  
pp. 371-385 ◽  
Author(s):  
Sonja Wolters ◽  
Klaus Zuberbühler
Keyword(s):  
Resource Competition ◽  
Dilution Effect ◽  
Daily Basis ◽  
Species Group ◽  
Mixed Species ◽  
Predator Detection ◽  
Vocal Behaviour ◽  
Forest Strata ◽  
Species Groups ◽  
Mixed Species Groups

AbstractOne of the most striking behavioural patterns of many forest primates concerns their tendency to live in semi-permanent mixed-species groups. Functional investigations have ascertained that individuals obtain some antipredator benefits without paying the costs of intra-species resource competition. Despite these advances, very little is known about the subtle mechanisms that keep mixed species groups together on a daily basis. Our results showed that in the Diana-Campbell's monkey association both species benefited from each other in diverse and idiosyncratic ways. In the presence of Campbell's monkeys the conspicuous Diana monkeys were more likely to descend into the lower forest strata, increased their foraging behaviour, and individuals became less vigilant. The cryptic Campbell's monkeys, in turn, were able to use the higher forest strata and exposed areas more often, spread out over larger areas, were more likely to travel, and engaged in more conspicuous vocal behaviour when associated with Diana monkeys. These data suggested that both species benefited from each other in ways that went beyond passive group-size related antipredator benefits, such as a dilution effect and increased chances of predator detection. Instead, the increased safety of the mixed species group allowed individuals to exploit their ecological niche more broadly, to forage more efficiently, and to engage in more social behaviour, suggesting that the benefits of mixed species groups are much more varied and diverse than currently thought.

Consequences of Joint-Territoriality in a Mixed-Species Group of Tamarin Monkeys

Behaviour ◽  
1992 ◽  
Vol 123 (3-4) ◽  
pp. 220-246 ◽  
Author(s):  
Carlos A. Peres
Keyword(s):  
Time Budget ◽  
Species Group ◽  
Foraging Efficiency ◽  
Home Ranges ◽  
Foraging Success ◽  
Territorial Defence ◽  
Saguinus Fuscicollis ◽  
Small Fruit ◽  
Tamarin Monkeys ◽  
Time And Energy

AbstractGroups of saddle-back (Saguinus fuscicollis) as moustached tamarins (Saguinus mystax) in a western Amazonian forest jointly defended home ranges larger than 100 ha, which were held in common throughout the year. Resources were defended by direct exploitation in extensive areas shared with other groups, or through intensive and frequent intergroup interactions along territorial boundaries. These interactions were expressed primarily during intergroup encounters, and affected the use of space, movements, time budget, and foraging success of tamarins. During encounters, animals of both species spent more time in energetically costly activities, such as rapid travel and intergroup chases, and less time in energetically positive activities, such as feeding and foraging. In addition, foraging success per unit of foraging effort within overlapping areas of the range periphery was lower than in exclusive areas of the range centre, particularly for saddle-back tamarins. The time and energy allocated by moustached tamarins to boundary contests was considerably greater than that of saddle-backs, despite the fact that only the latter species increased its foraging efficiency by shifting from exclusive areas in the group's range to those shared by other groups. This is probably because of saddle-back's greater use of depletable food supplies, such as small fruit patches and small microhabitats containing embedded prey items. These benefits are likely to justify the substantial amount of time and energy invested in territorial defence for both saddle-backs and moustached tamarins, but appeared to be highly asymmetric between species.

scholarly journals Can an Exponential Function Be Applied to the Asymptotic Density–Size Relationship? Two New Stand-Density Indices in Mixed-Species Forests

Forests ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 9 ◽  
Author(s):  
Gerónimo Quiñonez-Barraza ◽  
Hugo Ramírez-Maldonado
Keyword(s):  
Mortality Rate ◽  
Initial Density ◽  
Stand Density ◽  
Species Group ◽  
Mixed Species ◽  
Management Objectives ◽  
Density Index ◽  
Density Indices ◽  
Species Groups ◽  
Stand Density Index

This study presents two stand-density indices (SDIs) based on exponential density decline as a function of quadratic mean diameter for all species combined in mixed-species forests with 22 species mix grouped in four species groups. The exponential-based density–diameter relationship, as well the density index corresponding to the slope or instantaneous mortality rate parameters, was compared with those based on power-law density–diameter relationship. A dataset of 202 fully stocked circular plots at maximum density was used for fitting the models, and a dataset of 122 circular plots was used for validation stand density index for all species combined of mixed-species stands. The dataset for validation was independent of dataset for model development. The first stand-density index showed a density management graphic (DMG) with a variable intercept and common instantaneous mortality rate, and the second index showed a DMG with common intercept and variable mortality rate. Additionally, the value of the initial density of the fitted line was more realistic than those generated by the potential model for all species combined. Moreover, the density management diagrams showed a curvilinear trend based on the maximum stand density index in graphical log–log scale. The DMGs could be interpreted as forest scenarios based on variable initial density and common management objectives or the same density and different management objectives for forest-rotation periods involving all species combined in mixed-species stands. The fitting of exponential and potential equations for species or species groups showed that the density–size relationships in mixed-species forests should be modeled for all species combined because the disaggregation of mixture species represented a weak tendency for each species or species group and the resultant fitted equations were unrealistic.

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