Raptors provide an important ecosystem service by scavenging carcasses in agricultural landscapes

This post is from my PhD student Rebecca Peisley, who I co-supervised with Gary Luck. Rebecca submitted her thesis earlier this year. Find the paper here: The role of avian scavengers in the breakdown of carcasses in pastoral landscapes.  Also read Rebecca’s previous post on her other PhD work in apple orchards here.

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Animal carcasses such as deceased livestock, road-kill or culled animals are a fact of life in agricultural landscapes, and can encourage increased and unwanted visits from wild dogs and foxes and also contribute to the spread of disease. Scavenging birds in these landscapes can remove carcasses, and therefore provide an important ecosystem service for farmers.

Perhaps the most well-known examples of carcass removal services in agricultural landscapes, which are worth millions of dollars each year, are those provided by vultures in Europe, Asia and Africa. The removal of carcasses by vultures near human settlements can reduce the number and visitation rates of rabid dogs that would otherwise be attracted to the carcasses, and in so doing, reduce the spread of rabies to the human population.

Unfortunately, vulture populations have suffered severe declines in recent years, and do not occur worldwide. However, other bird groups such as raptors and corvids are also common scavengers and a diverse assemblage of these occur in Australia. Like vultures, the scavenging behaviour of raptors and corvids has the potential to reduce the prevalence of unwanted pests such as red foxes and wild dogs in the landscape, and also reduce the spread of diseases such as blowfly strike. However, the benefits of carcass removal in agroecosystems in Australia are not widely recognised and have not yet been quantified. Continue reading

Sustainable Agriculture: Best of 2016 & the wooden spoon

All good things come to an end. 2016 was a year just like any other; some dreadful things happened and some wonderful things happened, depending on who you talk to.

For people interested in sustainable agriculture, it was a pretty exciting year. But in keeping with the annual theme of misinformation, there were also plenty of fails. Here are some of the highlights for me: Continue reading

Cost-benefit trade-offs of bird activity in apple orchards

This is a guest post from my PhD student Rebecca Peisley, who I am co-supervising with Prof Gary Luck. Rebecca will submit her thesis early next year. She has been working on a really cool project looking at the costs and benefits of bird activity in apple orchards, vineyards and cattle grazing systems across south-eastern Australia; this blog is about her work in apple orchards.


Birds are commonly found in agroecosystems around the world and their foraging activities within crops can result in positive or negative outcomes for producers. For example, birds can help increase saleable yields by preying on insect pests that damage fruit, or removing leftover fruit after harvest, which helps prevent disease and assists in nutrient cycling. However, birds can also contribute to production losses by eating and damaging fruit before harvest, or preying on beneficial insect pollinators.

We cannot then assume that birds are simply ‘good’ or ‘bad’: the same species can in fact be ‘both’. But in our literature review, we showed that most studies of birds in agroecosystems have just considered either costs or benefits separately, which limits our understanding of how birds influence crop yields over spatial and temporal contexts.

In order then to gauge an overall outcome of bird activity, we look at both their beneficial and detrimental activities together in the same crop system and consider the trade-offs that exist between them. For example, the beneficial activity of insectivorous birds preying on pest insects in an apple orchard and reducing insect damage to fruit is traded off against the detrimental activity of the same birds preying on beneficial pollinators resulting in reduced fruit-set. Continue reading

Neonicotinoids linked to wild bee and butterfly declines in UK and US

Two long-term studies were published today showing comprehensive evidence that neonicotinoid use could have long-term effects on populations of non-target insects, especially wild pollinators. The studies look at wild bees in the UK and butterflies in California.

I wrote a piece for The Conversation on why I think these studies are important and how these results relate to Australia.

Read more: Neonicotinoids linked to wild bee and butterfly declines in Europe and US

Also see Jeff Ollerton’s great post on the UK bee study: Bees and pesticides – a major new study just published

© Manu Saunders 2016

Nature, food and people: there’s no magic bean for sustainable agriculture

If you believe your Twitter feed, every Jack and his beanstalk has the quick-fix solution we need to beat the sustainable food challenge. ‘If you want to eat meat, switch to pigs, birds & fish to generate fewer emissions’. That’s convenient, because ‘lettuce is three times worse than bacon for the environment’.

These solutions all sound pretty sexy. But reducing the environmental impact of food production is not as simple as choosing one crop or livestock type over another.

Food production is a social-ecological system. That means it’s a system based on a mutual relationship between nature and humans. The ecosystem (i.e. the farm) influences human lives and actions, via ecosystem services. And humans influence the ecosystem’s structure and function, through direct management and indirect drivers like regulations, subsidies, financial markets and consumer demand. Continue reading

Goodies v baddies? Why labelling wild animals as ‘pests’ or ‘friends’ is holding farming back

It’s hard to keep wild animals out of farms. Birds, mammals and insects all affect crop yields, in positive ways (such as flies pollinating flowers) and negative ones (such as when birds damage fruit).

Agricultural research and management programs often deal with these interactions by focusing on simplistic “good” and “bad” labels: aphids are annoying pests, for example, whereas bees are little angels.

Read the rest of our piece at The Conversation.

And see the papers behind the article here:

Saunders ME, Peisley RK, Rader R, Luck GW (2016) Pollinators, pests, and predators: Recognizing ecological trade-offs in agroecosystems. AMBIO 45:4-14.

Peisley RK, Saunders ME, Luck GW (2015) A systematic review of the benefits and costs of bird and insect activity in agroecosystems. Springer Science Reviews 3:113-125.

Emancipation, Evolution…and Agroecology: Lincoln & Darwin on land-sparing vs. land-sharing

Every year, I get to share my birthday with these guys:

darwinlincoln

I’ve been mildly obsessed with both of them for years, for obvious reasons. But it was only recently that I discovered their early contributions to the land-sharing/land-sparing debate, something directly relevant to my own work. Darwin’s ecological legacy is well-known, but how often do we consider Lincoln’s impact on environmental history? Continue reading