Asymmetric benefits of a heterospecific breeding association vary with habitat, conspecific abundance and breeding stage

Abstract Sexual segregation in foraging occurs in some species and populations of boobies (Sulidae), but it is not a general pattern. Sexual segregation in foraging may occur to avoid competition for food, and this competition may intensify during specific stages of breeding. We examined sexual segregation in foraging in relation to breeding stage in masked boobies Sula dactylatra at Rapa Nui by tracking simultaneously incubating and chick-rearing birds using GPS recorders (n = 18) and collected a total of 11 regurgitate samples. Stable isotope analyses (δ13C and δ15N) of whole blood samples were carried out in 20 birds. There were no differences in foraging trip parameters or diet between females and males. Both sexes traveled farther and for longer while incubating than while rearing chicks. Isotopic niches (δ13C and δ15N) overlapped to some degree among all groups at all times, but the lowest overlap between sexes occurred during incubation. While preying on ephemerally distributed flying fish, vertical or horizontal competition avoidance may be almost impossible, and thus females and males share their foraging grounds. Since birds were tracked simultaneously, shorter foraging trips of chick-rearing birds must be an effect of the constraints of provisioning the chick. Differences observed in δ15N and δ13C values between sexes may be caused by subtle differences in their foraging behaviors, or by differences in physiology linked to breeding. Our findings suggest that local oceanography and its inherent food distribution are determinants for sexual segregation in foraging patterns in masked boobies and possibly also other booby species. Significance statement In some animals, females and males forage on different areas or prey on different species to avoid competition for food resources. In boobies (Sula sp.), some studies show evidence of sexual segregation in foraging and others do not. Here, we tested if sexual segregation in foraging occurred in masked boobies on the Pacific island of Rapa Nui by studying simultaneously incubating and chick-rearing birds. We found no evidence of sexual segregation on foraging behavior or diet. We discuss that the difference between this and other studies in boobies may be an effect of the local prey availability. When the prey community is more diverse and heterogeneously distributed, each sex may access different resources and thus sexual foraging segregation will occur. In contrast, in areas like Rapa Nui where prey resources are distributed ephemerally, sexual segregation in foraging will not be useful and is thus less likely to occur.

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Specific responses of cuckoo hosts to different alarm signals according to breeding stage: a test of the offspring value hypothesis

Current Zoology ◽

10.1093/cz/zoaa021 ◽

2020 ◽

Vol 66 (6) ◽

pp. 649-655 ◽

Cited By ~ 1

Author(s):

Jiaojiao Wang ◽

Canchao Yang

Keyword(s):

Alarm Call ◽

Host Responses ◽

Alarm Calls ◽

Attack Behavior ◽

Brood Parasite ◽

Reed Warbler ◽

Defense Strategies ◽

Breeding Stage ◽

Accipiter Nisus ◽

Streptopelia Orientalis

Abstract The selective pressure exerted by avian brood parasites forces their hosts to evolve specific defense strategies. When subject to brood parasite attack, avian hosts will often emit alarm calls. To date, few studies have examined whether and how host responses to different alarm calls indicative of different enemies vary with the host’s breeding stage. We carried out alarm call playback experiments during both the egg and nestling stages of the oriental reed warbler Acrocephalus orientalis, a host of the common cuckoo Cuculus canorus. The playback exemplars were selected from recorded alarm calls of the warbler to the presence of common cuckoos, sparrowhawks Accipiter nisus, and oriental turtle doves Streptopelia orientalis, which represented brood parasite, predator, and harmless control, respectively. The results showed that the oriental reed warblers did not discriminate alarm calls issued to different intruder types, but the intensity of the response was significantly higher in the nestling stage than in the egg stage. Attack behavior related to sparrowhawk alarm calls was absent in the egg stage, but aggressive behavior increased dramatically and exceeded the attack frequency in response to the cuckoo alarm call in the nestling stage, implying a shift in the tradeoff between the parents’ own survival and the loss of offspring. Alarm calls attracted a larger number of conspecifics than members of other species. In general, the oriental reed warbler had consistently stronger responses to different alarm calls in the nestling stage than in the egg stage, supporting the offspring value hypothesis.

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Plastic ingestion risk is related to the anthropogenic activity and breeding stage in an Antarctic top predator seabird species

Marine Pollution Bulletin ◽

10.1016/j.marpolbul.2020.111351 ◽

2020 ◽

Vol 157 ◽

pp. 111351 ◽

Cited By ~ 1

Author(s):

A.E. Ibañez ◽

L.M. Morales ◽

D.S. Torres ◽

P. Borghello ◽

N.S. Haidr ◽

...

Keyword(s):

Anthropogenic Activity ◽

Top Predator ◽

Seabird Species ◽

Breeding Stage

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

Behaviour ◽

10.1163/156853904323066739 ◽

2004 ◽

Vol 141 (4) ◽

pp. 451-467 ◽

Cited By ~ 67

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.

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Parental Activities of Nesting Wood Storks Relative to Time of Day, Tide Level and Breeding Stage

Waterbirds ◽

10.1675/1524-4695(2005)028[0139:paonws]2.0.co;2 ◽

2005 ◽

Vol 28 (2) ◽

pp. 139-145 ◽

Cited By ~ 9

Author(s):

A. Lawrence Bryan ◽

Joel W. Snodgrass ◽

John R. Robinette ◽

Lara B. Hopkins

Keyword(s):

Time Of Day ◽

Breeding Stage ◽

Tide Level ◽

Wood Storks

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Breeding Stage and Environmental Factors Affect Prey Selection by Greater Crested Terns Off Southeast Australia

10.21203/rs.3.rs-193145/v1 ◽

2021 ◽

Author(s):

Katrin Quiring ◽

Gemma Carroll ◽

Eckhard Heymann ◽

Curtis Champion ◽

Robert Harcourt

Keyword(s):

Environmental Factors ◽

Diet Composition ◽

Foraging Behaviour ◽

Prey Selection ◽

Sea Surface ◽

Chick Growth ◽

Breeding Stage ◽

Marine Predators ◽

Selective Foraging ◽

Family Level

Abstract Variation in the diet of marine predators such as seabirds can be used to track environmentally-driven changes in ocean ecosystems. However, studies of predator diet must account for intrinsic influences on prey selection, such as changing nutritional requirements during breeding. Using digital photography, we investigated how the type and size of prey brought back to the colony by greater crested terns (Thalasseus bergii) changed in relation to breeding stage, and to variation in oceanographic conditions around Montague Island, Australia (36°15’S, 150°13’E). 2469 prey items were identified to species or family level over 35 consecutive days of photo-sampling in 2018. Australian anchovy (Engraulis australis), a surface-schooling clupeid fish, was the most abundant prey returned to the colony during all breeding stages (84.5%). The proportion of anchovy increased from 77.0% when birds were provisioning their adult partners during incubation, to 92.4% when they were provisioning chicks, suggesting selective foraging behaviour on this energy-dense species as a means to facilitate rapid chick growth. Anchovy size was largest during incubation (91.1 ± 14.9 mm), smallest during early chick provisioning (71.8 ± 11.0 mm), and increased slightly during mid-provisioning (79.6 ± 11.9 mm), indicating adaptive prey selection that is matched to the physical requirements of different breeding stages. The proportion of anchovy prey was also influenced by extrinsic environmental factors, with anchovy becoming more dominant with increasing local sea surface temperatures, up to ~17.5°C. Our findings highlight the importance of examining both intrinsic and extrinsic determinants of diet composition across breeding stages in seabird populations.

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Physiological Condition in Magellanic Penguins: Does it Matter if You Have to Walk a Long Way to Your Nest?

The Condor ◽

10.1093/condor/106.3.696 ◽

2004 ◽

Vol 106 (3) ◽

pp. 696-701

Author(s):

Brian G. Walker ◽

P. Dee Boersma ◽

John C. Wingfield

Keyword(s):

Body Condition ◽

Physiological Condition ◽

Colonial Species ◽

Ambient Temperatures ◽

Spheniscus Magellanicus ◽

Breeding Stage ◽

Magellanic Penguins ◽

Over Time

Abstract Colony edges, as opposed to interiors, are often considered less advantageous nesting places in colonial species. For temperate-breeding penguins, inland colony edges should be less desirable than other edges, as there are added costs of walking farther inland, and ambient temperatures are higher. During settlement and incubation, we compared body condition and baseline and stress-induced levels of the hormone corticosterone in male Magellanic Penguins (Spheniscus magellanicus) nesting on the sea edge of a colony with those nesting on the inland edge, >800 m from shore. Body condition in both groups was significantly lower during settlement than during incubation, but was similar in both groups within breeding stages. Corticosterone levels were similar between breeding stages and for groups within each breeding stage. While body condition can vary over time, penguins appear to be well buffered to physiological extremes, as they do not show modification of corticosterone levels with variations in nesting conditions. Condiciones Fisiológicas en el Pingüino Spheniscus magellanicus: ¿Tiene Importancia Caminar una Larga Distancia al Nido? Resumen. En especies coloniales, los bordes de la colonia son generalmente considerados como lugares menos ventajosos para el establecimiento de nidos. Para los pingüinos que crían en climas templados, los bordes de las colonias orientados tierra adentro deben ser menos deseables que otros bordes, ya que se suman los costos adicionales de caminar una distancia mayor desde la orilla y debido a que las temperaturas ambientes allí son más elevadas. Durante el establecimiento y la incubación, comparamos las condiciones corporales y los niveles de referencia e inducidos por estrés de la hormona corticosterona en los machos de Spheniscus magellanicus que anidaban en el borde de la colonia adyacente al mar con los que anidaban sobre el borde que mira hacia el interior, a más de 800 m desde la orilla. La condición corporal en los dos grupos fue significantemente menor durante el establecimiento que durante la incubación, pero fue similar en los dos grupos durante las etapas de crianza. Los niveles de corticosterona fueron similares para ambas etapas de crianza y para los dos grupos durante cada etapa de crianza. Aunque la condición corporal puede variar en el tiempo, los pingüinos parecen amortiguar bien los extremos fisiológicos, ya que no muestran modificación de los niveles de corticosterona con las variaciones en las condiciones de nidificación.

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