Right now the natural world has just one thing on its collective mind – to breed and to see itself perpetuated. You can see this in wispy dandelion seeds floating in the wind, the clouds of flower and tree pollen that might make you sneeze and the constant activity of our birds, mammals and insects as they forage and hunt to feed their young.
Underlying all of this new life is some serious weighing up of factors and risks, and probably a lot of trade-offs that the animals and plants are not even aware of.
It also requires some genetic hard-wiring and more than a pinch of luck. To make it is a fine balance of doing what you are designed to do best – pair up for life, return to a nest site year after year, have lots of young or only a few – and adapting to change – a warming climate, an unusually wet year, you are getting a bit older, your nest tree has blown down.
Taking some of the species to be seen at Muit of Dinnet just now here are some of the strategies at play.
The “Better Stay Together” crowd.
These are the strong pair-bonders. Great Crested Grebe, Mute Swan and Coot belong within this camp. Its all about team work.
Statistically pair bonds that last years improve the reproductive success of animals by enhancing coordination and cooperation between pair members. Pairs which have been together for longer can breed earlier, have more young and crucially have more young that survive to independence.
Great Crested Grebe
The stunning display of courting Great Crested Grebe is all about strengthening the pair bond. We have ” The head-shaking display” where they face each other and fan their ruffs, shaking their heads from side to side. This is used in early courtship or when the pair reunite after a seperation.
This is followed by the ‘weed ceremony’ which takes place just before the pair begin to build their nest platform. As part of this ceremony the two birds make a slow and deliberate dive to collect weed, before returning to the water’s surface and swimming towards each other, their heads held low to the surface. As they meet, the birds rise from to a vertical pose, which they hold by paddling their webbed feet rapidly, treading the water.
The length of parental care is quite long in the Coot, with the young only feeding themselves after about 30 days, much longer than in most rail species.Coot chicks look remarkably unlike the adults: they are fluffy, with tiny stunted wings, heads stained red and yellow, and with red bills.
Known for their grumpiness Coot aggression sometimes goes beyond adult rivalry into something more sinister.Coots are normally attentive parents, dividing the labour evenly between them – with the brood “split” between the two parents, with each adult feeding only its selected half.
But occasionally a parent can be seen to attack a chick, grabbing its head and shaking it, sometimes fatally. Superficially the very opposite of parental care, this extreme behaviour may be related to food supply, the birds ensuring that there are not too many chicks taking meagre resources. Luckily its been shown that this behaviour shows itself less in drier years so hopefully its looking good for Coot chick survival this year.
Most Swans find their mates before the age of 2 years – usually during the winter season and will nest for the first time together between 3 to 7 years old.
Swans are believed to form lifelong pair bonds. However, if one mate dies, the survivor will find another mate.
Swans require space to breed. Usually, only one pair nests on a single body of water with nesting territories ranging from 6 to 150 acres in size and often located near where the female was hatched. The female chooses the nesting area, while the male defends it.
The “Strength in Numbers” crowd – the colony breeders.
This strategy is about cooperation, babysitting duties, security (guarding) and information sharing (mostly about food). Cooperation between individuals can lead to both increased colony health and increased survival.
It includes our Lapwing who nest in loose colonies in the short grassland of the fields of New Kinord. For them its all about predator detection and escaping predation. Lapwing need a good view from the nest, which is why nests are usually placed on a slight mound or hummock.
The adults rely on the camouflaged patterning of their eggs and chicks, something that becomes more effective if the parent bird can spot a potential predator at a distance. The parents engage in active defence of their eggs and chicks by either flying at a predator or by a distraction display, an attempt to lure the predator away from the nest’s location, often by pretending to be wounded.
Nesting Lapwing also alter their behaviour if they are being watched by us, by making ‘false nest visits’ to an area that is not the nest.
Another strength in numbers breeder is – yes I am going to say the word – midge.
The midge swarm is all about mating.
Midge adults emerge simultaneously from water bodies to form swarms. It is believed that this behaviour is a mechanism to ensure the survival of the species by overwhelming their predators during the mating season with sheer numbers.
Midges are easiest to spot when groups of them dance in mid-air. What you’re seeing are the males saying to the females: here we are, where are you? They give off a signal that’s partly smell and partly sound. Sometimes they gather in such numbers that they make huge towers.
Only the females bite. They need a protein-rich meal of fresh blood in order to mature their eggs. Both the males and the females rely on sugar meals for energy for flight but the females need more than this to ensure the next generation. Female midges feed on the blood of birds and mammals.
The “Slow Burners” – those that breed late, have few young and live long. Also known as K-strategists.
We are K-strategists. This means that we invest in the quality not quantity of our offspring. K strategist belong to stable and predictable environments. Plants are subject to the same sorts of forces as animals.
A phenomenal example of a K strategist is the mighty Oak.
Oaks trees produce both male and female flowers. In spring, oak trees grow male (catkins) and female flowers on the same tree. Fertilisation occurs when the yellow mist of the male airborne pollen comes to rest on a receptive female flower on another tree, with a little help from the wind.
Oak trees grow very slowly and can take up to 40 years to produce their first acorns. As many as 50,000 acorns can be produced by an individual tree.
So what does it do until then? As oak trees grow they commit most of their energy to just that – growing. The tree’s height and size allow it to dominate other plants in the competition for sunlight. When it does reproduce, the oak produces large, energy-rich acorns that use their energy reserve to become quickly established.
Red Squirrels play their part here too. Acorns are irresistible to squirrels and are cached around the forest. However they rarely eat all the acorns they scavenge and hide and some will become established far from the parent tree.
The “Live fast, Die young” crowd. Also known as R-strategists
Those organisms typically live in unstable, unpredictable environments. Here the ability to reproduce rapidly is the highest priority.
Such organisms produce lots of young, but with little investment in any one individual, they are generally weak and easy to predate. The idea is to flood the habitat with so many that, regardless of predation or mortality, at least some will survive to reproduce.
The Dandelion is a perfect example.
When a dandelion sets seed, the flower (actually, hundreds of tiny florets) turns into a mass of seeds known as a dandelion clock.
The Bees and the Peas – the marriage of flower and pollinator
The peas here are the flowers of the pea family so wild flowers like vetches, clovers and bird-foots trefoil as well as many crops like beans, lentils, peanuts and soybeans.
The pea family is one of the highest level of flowering plants and provides the most energy rich food for pollinating insects.
However their specialised flowers have evolved to only be available to skilled pollinators such as honey bees, bumblebees and butterflies.
The flower design has evolved to produce an irregular and complex shape that can only be used by these pollinators . The richer the supply of food in quantity and quality, the more frequently and vigorously bees visit the source, skillfully transferring pollen from one plant to another.
This (over-time) favours the seed production of plants with higher content of sugar and proteins and with intense colours and odours.
The importance of Birds foot trefoil to our pollinators is massive. It’s an essential food plant for the young of many butterflies and moths, like the Common Blue butterfly and Six-spot Burnet moth.
In Scotland, three of our scarcest bee’s are completely dependent on the pollen of Bird’s-foot Trefoil: the pine-wood mason bee, the mountain mason bee and the wall mason bee.