Dr. David Kelly is a postdoctoral researcher in Prof Nicola Marples’ Behavioural and Evolutionary Ecology group in the Department of Zoology, Trinity College Dublin. His interests include ecology, biogeography, and evolution, and their interrelatedness.
Fire is an essential part of the ecology of many savannah and grassland ecosystems. In some cases, fire is the only way of removing older grasses that are no longer profitable for herbivores to consume. As well as having benefits for local ecology, grassland fires also offer great feeding opportunities. I have seen large groups of raptors and insectivorous birds gather at the fringes of bushfires in Kruger National Park, to take advantage of the animals flushed into the open by the moving fire front. In Australia, a number of raptors are frequently seen around bushfires. These birds; black kites (Milvus migrans), whistling kites (Haliastur sphenurus), and brown falcons (Falco berigora) are known as firehawks. In Malamalak, an Aboriginal language, the black kite is known as Kerrk, a reference to its call “kerrk-kerrk-kerrk“.There is an intriguing story about Kerrk:
It’s easy to forget that seasons work in different ways in different places. On a recent trip to Kruger National Park in South Africa, I was expecting to see European breeding birds. I was also expecting that South Africa would be enjoying a season similar to a European spring; a simple six-month discrepancy with the northern hemisphere. While I found the European birds, including Swifts, Swallows, Cuckoos and Willow Warblers, I found a rather different type of spring. South Africa has very short transition seasons (spring/autumn) and more extended hot/cold (winter/summer) seasons. Over much of South Africa, summer (mid-October to mid-February) is a hot and sunny season, frequently accompanied by afternoon thunderstorms. In Kruger, summer is marked by the beginning of the “wet” season and the birth of new Impala, Wart Hogs and Wildebeest. However, the majority of the resident mammals don’t have a breeding “season”; all of the “Big 5” (buffalo, elephant, rhino, leopard and lion), can give birth to young in any month.
Elephant Herd Mud-bathing
The native people of the Limpopo and Mpumalanga provinces have incorporated the link between the birth of impala and the arrival of rain into folklore. Their stories say that impala are the animals that decide when it should rain. If the rain is early, the impala need it early, if the rain is late, the impala are not ready for it at the usual time. While I thought that might make the impala unpopular, it seems they are held in high esteem.
Baby Impala
As well as the transcontinental migrant birds (like the Swallows and Cuckoos I mentioned earlier), Africa has numerous bird species which migrate within the continent. In November (the date of my visit), the Woodland Kingfishers arrive in Kruger.
Woodland Kingfisher – displaying
Their arrival is probably timed to coincide with the rise in insect numbers, following the new growth triggered by the rains, because Woodland Kingfishers feed on grasshoppers, locusts and beetles, rather than fish.
Cicada Pupal Case
For an ecologist, migration is a fascinating area of study, especially when closely-related species compete for food at different times of year. Indeed, the migrant Woodland Kingfishers compete with resident Brown-hooded Kingfishers for food. By coincidence, a study considering such questions has just started in Kruger.
While there is irrefutable evidence for the transfer of bovine TB between badgers and cattle, the mechanisms of transfer are not clearly documented. In order to reduce such transfer, it is obviously important to understand how infection takes place.
With such questions in mind, data from a study of free-ranging badgers was combined with detailed records of paddock use by cattle. Each study badger was carrying a personal GPS unit on a tailored collar, so their movements could be monitored to within a few meters. The paddock use of the cattle was recorded on a daily basis. The data were combined, using mapping software, such that a daily log could be constructed for badger and cattle activity. Continue reading “Do badgers play Friesian tag?”
While most of the younger generations are familiar with the ideas behind Jurassic Park, they are probably also aware that, despite the best efforts of geneticists, there is no possibility of conjuring up a T. Rex from the fossilised remnants that are on display in museums.
However, there are plans afoot to attempt a similarly ambitious project with species that have disappeared from the earth more recently. These reintroduction programmes, where there are currently no living relatives to repopulate the species, have been termed “de-extinction”. The Long Now Foundation (a private, not-for-profit organisation committed to very long-term thinking about the human population) has conceived a Revive and Restore Project that aims to return some of the planet’s missing biodiversity. Candidate species have already been identified and include; the Passenger Pigeon (US), the Great Auk (Europe), the Dodo (Mauritius),the Huia (New Zealand), the Tasmanian Tiger (Australia) and the Woolly Mammoth (Russia). Continue reading “Undead as a dodo?”
The food chain is a concept that many non-biologists are familiar with. Ecologically-speaking, this should be referred to as a food web, because there is rarely one prey species for a given predator or one predator of any given species.
The biochemistry of metabolism and digestion means we can reconstruct the diet of a member of a given food web with some basic information about the stable isotopes in its tissues and the stable isotope values of the available prey. Simply put, “you are what you eat”. Carbon isotopes generally reflect the “where” of the diet and nitrogen isotopes generally indicate the “what”.
This overview omits several complications. Firstly, the calculation of diet requires a “conversion factor” (trophic enrichment factor or TEF) for any given tissue of an animal. Animal metabolisms tend to retain 15N, so consumers have greater 15N:14N ratios than their prey. Secondly, each tissue is likely to have a different TEF, as it is made to perform a different job in the animal. Thirdly, TEFs can only be derived by feeding animals highly controlled diets, ideally a single food for the length of time it takes for the study tissue to be fully replaced. In the case of teeth and bone, this can be months or even years.
As there are relatively few TEFs available for animal species, many ecologists “borrow” TEFs from other species for their calculations. Having derived TEFs for carbon and nitrogen in badger blood serum, a tissue that is completely replaced several times a month, we demonstrated that badger TEFs differ from fox TEFs. This is important, as foxes are similar in size to badgers and have a similar feeding ecology, and ecologists might be tempted to “borrow” fox TEFs to use in badger studies.
So knowing more about the biochemistry of badgers (in the form of TEFs) will allow us to learn more about their diets. This may be of importance to farmers planning biosecurity measures for their farms, as they will be able to learn if badgers are raiding their crops (in the field or in the barn). It will also help identify when badgers are specialising on different foods and potentially allow farmers to minimise contact between badgers and livestock.
For over 10 years we have been making regular visits to islands in the Sulawesi region of Indonesia. We trap birds on these islands, collecting morphometric data. Each bird we trap is measured, marked with a plastic ring and released. As our dataset grows we gain more insight into the lives of the birds on these islands.
In 2007 and 2010 we visited the island of Kaledupa in the Wakatobi archipelago. In 2010 we made a point of revisiting all of the sites we had trapped at in 2007. This gave us an opportunity to look for the birds we had originally caught in 2007. Continue reading “Is island life easier?”
