Migration in a landscape of fear - stopover ecology in European robins
(2022) BION02 20212Degree Projects in Biology
- Abstract
- Long-distance bird migrants face three main constraints: time, energy, and predation risk during migration. As a result, their migratory strategies may be altered. Since migratory birds spend most of their time refueling during migration, they are particularly vulnerable to predation risk at stopover sites. The trade-off between energy intake and predation risk is widely acknowledged. However, there are only a limited number of studies on how predator pressure affects fueling and feeding strategies in migratory birds. In this study, we brought first-year European robins Erithacus rubecula into the lab, conducted playback experiments to investigate how diurnal and nocturnal predator perceptions influenced fueling and mass change at a... (More)
- Long-distance bird migrants face three main constraints: time, energy, and predation risk during migration. As a result, their migratory strategies may be altered. Since migratory birds spend most of their time refueling during migration, they are particularly vulnerable to predation risk at stopover sites. The trade-off between energy intake and predation risk is widely acknowledged. However, there are only a limited number of studies on how predator pressure affects fueling and feeding strategies in migratory birds. In this study, we brought first-year European robins Erithacus rubecula into the lab, conducted playback experiments to investigate how diurnal and nocturnal predator perceptions influenced fueling and mass change at a stopover site in southern Sweden during autumn migration. As a result, robins responded differently to diurnal (Eurasian Sparrowhawk Accipiter nisus) and nocturnal (Tawny owl Strix aluco) predators. The robins increased fueling and feeding rates when the diurnal predator was perceived, but when the nocturnal predator was heard, they lost significant weight and then recovered their fueling and feeding rates. The fueling pattern observed in the latter experiment differed from previous periods, assuming a mix of residents and migrants in the experimental group with different responses. In conclusion, different motivations of migratory birds may explain the fueling patterns observed in this study; predator pressure may trigger extra fueling, suggesting a potential departure decision. In addition, robins appeared to be more sensitive to nocturnal predators. Fueling strategies could also differ depending on the time during the migration season. This study suggests that the perception of different predators could affect fueling and feeding performance in migratory passerines, potentially influencing their migration decisions, and shaping the landscape of fear temporally and spatially at stopover sites. (Less)
- Popular Abstract
- Being fat or lean? How birds migrate in a fear of predators
Imagine that you are exhausted and hungry, and you need to find a place to rest and replenish energy before continuing your journey. Eating too much, however, may impair your movement efficiency, increasing the risk when encountering a dangerous situation. In such a situation, how will you make your decision? Indeed, this is one of the most difficult challenges that migratory birds face during migration. Because birds spend the majority of their time refueling at stopover sites, they are thought to be the most vulnerable due to predation activity. As a result, a trade-off between energy intake and predation risk was introduced; we were curious to know how the fear of predators... (More) - Being fat or lean? How birds migrate in a fear of predators
Imagine that you are exhausted and hungry, and you need to find a place to rest and replenish energy before continuing your journey. Eating too much, however, may impair your movement efficiency, increasing the risk when encountering a dangerous situation. In such a situation, how will you make your decision? Indeed, this is one of the most difficult challenges that migratory birds face during migration. Because birds spend the majority of their time refueling at stopover sites, they are thought to be the most vulnerable due to predation activity. As a result, a trade-off between energy intake and predation risk was introduced; we were curious to know how the fear of predators would affect migratory birds' fueling strategy, whether they would eat more or eat less.
We brought first-year European robins Erithacus rubecula into the lab, designed three playback experiments, with experiment 1 and 3 including a diurnal predator (Sparrowhawk Accipiter nisus), comparing the responses between early and late season. Experiment 2 instead included a nocturnal predator (Tawny owl Strix aluco), to see if birds’ reaction would differ between different predators. Birds in the control groups were exposed to calls from non-harmful animals. Body mass and food intake would be recorded every 24 hours, and we expected to see birds either increase or decrease their fueling rate (staying fat or lean) when perceiving the dangers.
As a result, robins exposed to Sparrowhawk calls chose to stay fat, while the birds exposed to Tawny owl appeared to stay lean. It is possible that birds were more sensitive to nocturnal predators and became extremely stressed when they heard them nearby. Still, we may ask why birds choose to eat more despite the perceived risk when exposed to Sparrowhawk calls? Since they did not have any refuges to escape to, it may have been most feasible to reserve more fat and leave this dangerous place as soon as possible.
Migratory robins used different strategies when confronted with different type of dangers. Despite being afraid of predators, birds would rather gain weight in order to leave the danger when encountering a diurnal predator. However, it appears wiser to remain vigilant when nocturnal predators are present. For juvenile robins, this may be due to a lack of experience from encounters with Tawny owls. Being fat or lean? It is difficult to say which is the best option, we have provided evidence that the strategies may differ depending on the type of predator birds are exposed to. It would also be interesting to include activity data in future research, to observe birds' behavioral responses, and gain a better understanding of their migration decisions in the face of predators.
Supervisor: Susanne Åkesson (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9103236
- author
- Wu, Xiaojia
- supervisor
- organization
- course
- BION02 20212
- year
- 2022
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 9103236
- date added to LUP
- 2022-11-16 09:28:49
- date last changed
- 2022-11-16 09:28:49
@misc{9103236,
abstract = {{Long-distance bird migrants face three main constraints: time, energy, and predation risk during migration. As a result, their migratory strategies may be altered. Since migratory birds spend most of their time refueling during migration, they are particularly vulnerable to predation risk at stopover sites. The trade-off between energy intake and predation risk is widely acknowledged. However, there are only a limited number of studies on how predator pressure affects fueling and feeding strategies in migratory birds. In this study, we brought first-year European robins Erithacus rubecula into the lab, conducted playback experiments to investigate how diurnal and nocturnal predator perceptions influenced fueling and mass change at a stopover site in southern Sweden during autumn migration. As a result, robins responded differently to diurnal (Eurasian Sparrowhawk Accipiter nisus) and nocturnal (Tawny owl Strix aluco) predators. The robins increased fueling and feeding rates when the diurnal predator was perceived, but when the nocturnal predator was heard, they lost significant weight and then recovered their fueling and feeding rates. The fueling pattern observed in the latter experiment differed from previous periods, assuming a mix of residents and migrants in the experimental group with different responses. In conclusion, different motivations of migratory birds may explain the fueling patterns observed in this study; predator pressure may trigger extra fueling, suggesting a potential departure decision. In addition, robins appeared to be more sensitive to nocturnal predators. Fueling strategies could also differ depending on the time during the migration season. This study suggests that the perception of different predators could affect fueling and feeding performance in migratory passerines, potentially influencing their migration decisions, and shaping the landscape of fear temporally and spatially at stopover sites.}},
author = {{Wu, Xiaojia}},
language = {{eng}},
note = {{Student Paper}},
title = {{Migration in a landscape of fear - stopover ecology in European robins}},
year = {{2022}},
}