Tag Archives: migration

The Cost Of Small-Scale Hunting On A Big-Scale Bird

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Achieving international biodiversity targets: learning from local norms, values and actions regarding migratory waterfowl management in Kazakhstan (2022) Jones et al., Journal of Applied Ecology, https://doi.org/10.1111/1365-2664.14198

The Crux

Some species that we consider local treasures have ranges that extend over vaste swathes of the planet, and some of these make use of those entire ranges. This is probably most obvious in bird species. Some of the locals that have been popping up in my neighbourhood as spring kicks off have been spending the winter on the other half of the planet, and have made use of countless other locations on their journeys between the two endpoints.

This makes conservation a headache. Just because a species is beloved and protected at one end of its range doesn’t mean it’s afforded the same luxury at another end. Even if the species is internationally recognised as threatened, that doesn’t mean every location it visits will respect – or even be aware – of this status. That means that to protect migratory species, we need to figure out the most important parts of their ranges, and work with the people who live there to ensure the birds persist. Today’s paper is an investigation into how effective this sort of work could prove in the future.

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The Waze

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Migration – that big annual event where some animals ‘pack up and ship out’ when the season starts to turn and better pastures are to be found elsewhere. Although we may not really understand how bird migration routes work, we do know that they seem to be ‘pre-programmed’ – individuals don’t typically veer off of the designated route (although some individuals might get blown off course and a bit turned around).

That being said, long-term observation of Richard’s pipits has revealed that (at least some of them) have exchanged their usual north-south migration route in and out of Russia for an east-west alternative. Although we might not be 100% sure what caused these individuals to recalculate their routes, it does open the door for some more questioning with regards to the flexibility and ‘reprogrammability’ of these long-standing migration routes.

You can read the research article at the link below:

A new westward migration route in an Asian passerine bird

It’s Not How You Get There, But When

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When migrating, animals like the great white pelican have to walk the fine line between saving time and saving energy. (Image Credit: Ray in Manila, CC BY 2.0, Image Cropped).

Landscape-dependent time versus energy optimisations in pelicans migrating through a large ecological barrier (2019) Efrat et al., Functional Ecology, https://dx.doi.org/10.1111/1365-2435.13426

The Crux

We have all seen the amazing scenes in nature documentaries of the great seasonal migrations undertaken by many different species on this planet. By migrating between two different habitats, migrating animals are thought to maximize both how many resources they have access to, and to minimize their exposure to harsh environmental conditions.

Despite these benefits gained by migrating animals, there are risks associated with these seasonal, long-distance travel events. Migrating animals, like the great white pelican (Pelecanus onocrotalus), have to decide what is better: traveling for a shorter distance or using less energy by taking a less strenuous – but longer – path. Today’s authors tracked the great white pelican during its seasonal migration over the Sahara to study how these birds made decisions about their travel.
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The Motivation Behind Migration

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Species like this red-crowned crane perform yearly migrations, but how do they weigh up the costs and benefits? (Image Credit: Alistair Rae, CC BY-SA 2.0, Image Cropped)

Where the wild birds go: explaining the differences in migratory destinations across terrestrial bird species (2018) Somveille, Manica & Rodrigues. Ecography, 42, p. 225-236.

The Crux

Migratory birds make up a huge chunk of the world’s bird life, yet there are still a lot of gaps in our knowledge concerning why they migrate to the areas they do. There’s a variety of potential benefits to migration, from remaining within a comfortable temperature range or a preferred habitat, to gaining access to areas that have a surplus in resources, to escaping competition with resident species. However, migration also results in increased mortality due to the amount of energy it takes. This week’s study tried to analyse the drivers of migration, and what trade-offs were made between migration’s potential benefits and costs.

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