scholarly journals Male White-shouldered Fairywrens (Malurus alboscapulatus) elevate testosterone when courting females but not during territorial challenges

2021 ◽  
Author(s):  
Jordan Boersma ◽  
John Anothny Jones ◽  
Erik D Enbody ◽  
Joseph F Welklin ◽  
Serena Ketaloya ◽  
...  
Keyword(s):  
Bird Species ◽  
Plasma Testosterone ◽  
Network Approach ◽  
Challenge Hypothesis ◽  
Agonistic Interactions ◽  
Causal Factors ◽  
Behavioral Traits ◽  
Social Network Approach ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion

Testosterone mediates suites of physical and behavioral traits across vertebrates, and circulation varies considerably across and within taxa. However, an understanding of the causal factors of variation in circulating testosterone has proven difficult despite decades of research. According to the challenge hypothesis, agonistic interactions between males immediately prior to the breeding season produce the highest levels of testosterone measured during this period. While many studies have provided support for this hypothesis, most species do not respond to male-male competition by elevating testosterone. As a result, a recent revision of the hypothesis (challenge hypothesis 2.0) places male-female interactions as the primary cause of rapid elevations in testosterone circulation in male vertebrates. Here, we offer a test of both iterations of the challenge hypothesis in a tropical bird species. We first illustrate that male White-shouldered Fairywrens (Malurus alboscapulatus) differ by subspecies in plasma testosterone concentrations. Then we use a social network approach to find that males of the subspecies with higher testosterone are characterized by greater social interaction scores, including more time aggregating to perform sexual displays. Next, we use a controlled experiment to test whether males respond to simulated territorial intrusion or courtship interaction contexts by elevating testosterone. Males sampled during courtship had greater plasma testosterone both relative to flushed controls and males sampled during simulated intrusion. Ultimately, our results are consistent with challenge hypothesis 2.0, as males rapidly elevated testosterone following interactions with females, but not during territorial challenges.

Opposite Changes in Plasma Testosterone and Corticosterone Levels Following a Simulated Territorial Challenge in Male Great Tits

Behaviour ◽  
2004 ◽  
Vol 141 (4) ◽  
pp. 451-467 ◽  
Author(s):  
Rianne Pinxten ◽  
Lutgarde Arckens ◽  
Els van Duyse ◽  
Marcel Eens ◽  
Veerle Darras
Keyword(s):  
Parus Major ◽  
Time Of Day ◽  
Behavioural Response ◽  
Egg Laying ◽  
Plasma Testosterone ◽  
Breeding Cycle ◽  
Territorial Defence ◽  
Breeding Stage ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion

AbstractThe apparent ability of plasma testosterone (T) and corticosterone (B) levels to fluctuate rapidly in response to agonistic interactions, suggests that these hormones may play an important role in an animal's acute behavioural response during such interactions. In the present study, free-living male great tits, Parus major, were subjected to a simulated territorial intrusion (STI) during the egg laying, incubation and nestling stage of first broods. Plasma T and B levels of challenged males were compared to those of control males matched for breeding stage, day in breeding stage, and time of day. Plasma B levels were significantly higher in challenged males compared to control males during the egg laying and incubation stage but not during the nestling stage. On the other hand, challenged males had significantly lower plasma T levels than control males throughout the breeding cycle. While having low plasma T and elevated plasma B levels, challenged males showed a vigorous and unrelenting territorial response to the STI. Plasma T and B levels of challenged males did not correlate with the intensity of the behavioural response to the STI. These findings do not agree with the predictions of the 'challenge hypothesis' that males exposed to a territorial challenge while having breeding baseline T levels will respond with an increase in T or that T correlates with the intensity of aggression during a challenge. Together, our findings suggest a role for B rather than T in the regulation of territorial defence in male great tits.

scholarly journals Free-Living Male Mountain White-Crowned Sparrows Exhibit Territorial Aggression Without Modulating Total or Free Plasma Testosterone

The Condor ◽  
2007 ◽  
Vol 109 (1) ◽  
pp. 173-180 ◽  
Author(s):  
Sharon E. Lynn ◽  
Thomas P. Hahn ◽  
Creagh W. Breuner
Keyword(s):  
Aggressive Behavior ◽  
Free Testosterone ◽  
Plasma Testosterone ◽  
Zonotrichia Leucophrys ◽  
Territorial Aggression ◽  
Testosterone Secretion ◽  
Corticosteroid Binding Globulin ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion ◽  
Free Plasma

Abstract Abstract In some species, expression of territorial aggression is accompanied by a rise in testosterone secretion, but in others aggressive behavior is expressed while testosterone levels remain unchanged. Corticosteroid binding globulin (CBG) binds both corticosterone and testosterone in avian plasma. Thus, increasing corticosterone may result in fluctuations in unbound (“free”) testosterone; this could result in greater biological activity of testosterone without an increase in testosterone secretion. We investigated whether such plasma interactions of testosterone, corticosterone, and CBG might result in alterations of free testosterone in male Mountain White-crowned Sparrows (Zonotrichia leucophrys oriantha). We conducted simulated territorial intrusions during incubation and compared total and free testosterone of males captured immediately following a simulated territorial intrusion with that of males captured passively. All experimental males showed aggressive behavior, but apparently did not modulate total or free testosterone relative to controls.

scholarly journals Defending as a unit: sex- and context-specific territorial defence in a duetting bird

2020 ◽  
Author(s):  
Lucia Mentesana ◽  
Maria Moiron ◽  
Ernesto Guedes ◽  
Enzo Cavalli ◽  
Bettina Tassino ◽  
...  
Keyword(s):  
Structural Equation Modelling ◽  
Latent Variable ◽  
Structural Equation ◽  
Bird Species ◽  
Correlation Pattern ◽  
Territorial Defence ◽  
Equation Modelling ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion ◽  
Context Specific

AbstractBehaviours such as territorial defence represent functionally integrated traits that underlie multiple behavioural variables such as physical and acoustic responses. Characterizing the multivariate structure of such traits is fundamental to understand their evolution. In bird species that form stable pair bonds and are territorial year-round, both sexes are expected to defend their territory; however, the role that each sex plays in defending their shared territory remains largely unknown. Evidence for the sex-roles during territorial defence is mixed and sex- and context-specific characterizations of territorial defence embracing the multivariate nature of the trait are currently lacking. Here we investigated sex- and context-specific variation in a hypothesised latent variable called “territorial defence” and tested whether duets were part of territorial defence in a wild population of rufous hornero (Furnarius rufus). To do so, we combined a simulated territorial intrusion approach during nest building and provisioning contexts with a structural equation modelling approach. Our results showed that, in males and females, the six measured behavioural variables were linked by a single latent trait, territorial defence, in both contexts. Flights over the decoy and duet songs were equally good proxies of territorial defence. Although males were defending more the territory than females, pair members showed a positive correlation in their behaviour. The structural equation modelling framework enabled us to capture a complex correlation pattern among behavioural variables, expanding upon a classic body of research on territorial defence. Thus, the combination of classical behavioural approaches with sophisticated statistical analyses brings new exciting possibilities to the field of behavioural ecology.Significance statementTerritorial defence is a key behaviour in territorial species as it plays a major role in an individual’s reproductive success and survival. Additionally, territorial defence has been proposed as one possible evolutionary driver of duetting behaviour, one of the most fascinating vocal behaviours in birds. As behaviours are evolutionary characters, they must be studied in a multivariate framework. In this study we focused on characterizing territorial defence during a simulated territorial intrusion in an integrative manner using a classical territorial intrusion framework. We did so in male and female rufous horneros (Aves: Furnaridae) across two breeding contexts, while simultaneously testing theoretical predictions about the role of duetting behaviour as key part of territorial defence. Overall, our study provides for the first time a sex- and context-comparison of the multivariate, latent variable “territorial defence” in duetting birds, while highlighting the potential of combining field behavioural approaches with structural equation modelling.

scholarly journals Territorial Movements of Black-throated Blue Warblers in a Landscape Fragmented by Forestry

The Auk ◽  
2001 ◽  
Vol 118 (2) ◽  
pp. 544-549 ◽  
Author(s):  
Rebecca J. Harris ◽  
J. Michael Reed
Keyword(s):  
Bird Species ◽  
Small Scale ◽  
Neotropical Migrant ◽  
Dendroica Caerulescens ◽  
Alarm Calling ◽  
Second Year ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion ◽  
Song Playback ◽  
Older Males

Abstract Many forest bird species show inhibition to entering open areas, including crossing habitat gaps. We examined the responses of Black-throated Blue Warblers (Dendroica caerulescens) to conspecific song playback within forest, at clearcut-forest ecotones, and across logging roads to assess movements of this Neotropical migrant into open areas. Males responded readily to song playbacks in all areas, and moved significantly farther into clearcuts than they did within intact forest (40.4 ± 2.9 m and 17.1 ± 1.2 m, respectively). Their singing, aggressive trilling, and alarm-calling rates were highest in response to playback from clearcuts, intermediate during road-crossings, and lowest within forest. Males moved farthest into the oldest regenerating clearcuts (>15 years old), indicating that vegetation structure also influences their movement into open areas. Second-year males were more responsive than older males, moving farther to reach speakers in all areas, and showing a nonsignificant trend of moving farther into clearcuts. We found that extensive movements into open areas occur in response to simulated territorial intrusion, indicating that small-scale habitat fragmentation by forestry may not disrupt territorial movements of that species.

scholarly journals Ignoring the challenge? Male black redstarts ( Phoenicurus ochruros ) do not increase testosterone levels during territorial conflicts but they do so in response to gonadotropin-releasing hormone

2011 ◽  
Vol 278 (1722) ◽  
pp. 3233-3242 ◽  
Author(s):  
Beate Apfelbeck ◽  
Wolfgang Goymann
Keyword(s):  
Breeding Season ◽  
Gonadotropin Releasing Hormone ◽  
Plasma Testosterone ◽  
Releasing Hormone ◽  
Social Challenges ◽  
Testosterone Levels ◽  
Territorial Conflicts ◽  
Territory Defence ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion

Competition elevates plasma testosterone in a wide variety of vertebrates, including humans. The ‘challenge hypothesis’ proposes that seasonal peaks in testosterone during breeding are caused by social challenges from other males. However, during experimentally induced male–male conflicts, testosterone increases only in a minority of songbird species tested so far. Why is this so? Comparative evidence suggests that species with a short breeding season may not elevate testosterone levels during territory defence. These species may even be limited in their physiological capability to increase testosterone levels, which can be tested by injecting birds with gonadotropin-releasing hormone (GnRH). We studied two populations of black redstarts that differ in breeding altitude, morphology and the length of their breeding season. Unexpectedly, males of neither population increased testosterone in response to a simulated territorial intrusion, but injections with GnRH resulted in a major elevation of testosterone. Thus, black redstarts would have been capable of mounting a testosterone response during the male–male challenge. Our data show, for the first time, that the absence of an androgen response to male–male challenges is not owing to physiological limitations to increase testosterone. Furthermore, in contrast to comparative evidence between species, populations of black redstarts with a long breeding season do not show the expected elevation in testosterone during male–male challenges.

scholarly journals Interdicting International Drug Trafficking: a Network Approach for Coordinated and Targeted Interventions

2021 ◽  
Author(s):  
Luca Giommoni ◽  
Giulia Berlusconi ◽  
Alberto Aziani
Keyword(s):  
Law Enforcement ◽  
Drug Trafficking ◽  
Network Approach ◽  
Targeted Interventions ◽  
Cross Border ◽  
Edge Betweenness ◽  
Different Types ◽  
Social Network Approach ◽  
The Impact ◽  
International Trafficking

AbstractThere is a relative dearth of literature on both the effects of cross-border interdictions and the impact of different types of interventions on international drug trafficking. This study identifies the main trafficking routes for cocaine and heroin, along with comparing the disruptive effects induced by targeted and non-coordinated interventions. It adopts a social network approach to identify the routes along which cocaine and heroin are trafficked, and then simulates the impact of different interdiction strategies on these two trafficking networks. The findings indicate that targeting countries based on their respective positions in the networks, as opposed to on the basis of the quantity of drugs exchanged, is more likely to disrupt drug flows. More specifically, concentrating law enforcement resources on countries with several incoming or outgoing trafficking connections, or those countries that mediate between producer, transit and consumer countries, would appear to be particularly effective in this regard. Interventions focused on specific trafficking routes are also likely to be effective if these routes have high edge betweenness centrality scores. This study contributes to extant understanding on the vulnerability of cocaine and heroin international trafficking networks, and, moreover, demonstrates that empirically-driven strategies are potentially more effective at interdicting international trafficking than non-strategic and non-coordinated interventions.

scholarly journals Testing the Likeable, Therefore Abundant Hypothesis: Bird Species Likeability by Urban Residents Varies Significantly with Species Traits

Land ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 487
Author(s):  
Lillian Collins ◽  
Grant D. Paton ◽  
Sara A. Gagné
Keyword(s):  
Undergraduate Students ◽  
Species Conservation ◽  
Bird Species ◽  
Bird Community ◽  
Species Traits ◽  
Community Change ◽  
Habitat Availability ◽  
Urban Residents ◽  
Behavioral Traits

The urbanization of landscapes filters bird communities to favor particular species traits, driven in part by the changes that homeowners make to the amount and quality of habitat in yards. We suggest that an ultimate driver of these proximate mechanisms underlying bird community change with respect to urbanization is the likeability of species traits by urban residents. We hypothesize that bird species likeability, modulated by species traits, influences the degree to which homeowners alter the availability and quality of habitat on their properties and thereby affects species population sizes in urbanized landscapes. We refer to this new hypothesis as the Likeable, therefore Abundant Hypothesis. The Likeable, therefore Abundant Hypothesis predicts that (1) bird species likeability varies with species morphological and behavioral traits, (2) homeowners use trait-based likeability as a motivator to modify habitat availability and quality on their properties, and (3) residential habitat availability and quality influences species populations at landscape scales. We tested the first prediction of the Likeable, therefore Abundant Hypothesis using a survey of 298 undergraduate students at the University of North Carolina at Charlotte who were asked to rank their preferences for 85 forest generalist and edge/open country songbird species grouped according to 10 morphological and behavioral traits. Survey respondents preferred very small, primarily blue or black species that are insectivorous, aerial or bark foragers, residents, and culturally unimportant. On the other hand, respondents disliked large or very large, primarily yellow or orange species that forage on the ground and/or forage by flycatching, are migratory, and are culturally important. If the Likeable, therefore Abundant Hypothesis is true, natural resource managers and planners could capitalize on the high likeability of species that are nevertheless negatively affected by urbanization to convince homeowners and residents to actively manage their properties for species conservation.

scholarly journals Current States and Future Trends in Safety Research of Construction Personnel: A Quantitative Analysis Based on Social Network Approach

2021 ◽  
Vol 18 (3) ◽  
pp. 883
Author(s):  
Xiangcheng Meng ◽  
Alan H. S. Chan
Keyword(s):  
Social Network ◽  
Path Analysis ◽  
Construction Industry ◽  
Occupational Safety ◽  
Future Trends ◽  
Network Approach ◽  
Main Path ◽  
Safety Research ◽  
Main Path Analysis ◽  
Social Network Approach

The construction industry is recognized as a high-risk industry given that safety accidents and personnel injuries frequently occur. This study provided a systematic and quantitative review of existing research achievements by conducting social network approach to identify current states and future trends for the occupational safety of construction personnel. A total of 250 peer-reviewed articles were collected to examine the research on safety issues of workers in construction industry. Social network approach was applied to analyze the interrelationship among authors, keywords, and citations of these articles using VOS viewer and CitNetExplorer. A knowledge structure map was drawn using main path analysis (MPA) towards the collected papers, which was implemented by Pajek. In line with the findings of social network analysis, five research groups, and six keyword themes were identified in accordance with the times of cooperation of researchers and correlation among keywords of the papers. Core papers were identified by using main path analysis for each research domain to represent the key process and backbone for the corresponding area. Based on the finding of the research, significant implications and insights in terms of current research status and further research trends were provided for the scholars, thus helping generate a targeted development plan for occupational safety in construction industry.

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