courtship

What our animals are doing this month….

April 22, 2021 by Admin

May is an excellent time of year to look out for our native legless lizard, the slow-worm. Breeding takes place in May and this can be a dramatic process to witness. Not only do males compete aggressively over mates, but during courtship they will grasp the female roughly by the neck, and mating can then last for up to 10 hours! Courtship is easily mistaken for fighting, so being able to tell males and females apart can be helpful. Male slow-worms are grey or brown all over, and some have bright blue spots along the back. Females are usually brown on top with dark sides and belly, and a dark line down the back.

Slow-worms are a common garden species and the perfect gardener’s friend, as they love to eat garden pests such as slugs. They are particularly fond of compost heaps and warm hiding places such as log piles or under tin roofing, so these are good places to look for them. Despite their snake-like appearance, slow-worms can be distinguished from snakes by their shiny appearance, bullet-shaped heads, and blinking abilities (snakes lack eyelids!)

A pair of courting slow-worms (Photo: Lin Wenlock)

What our animals are doing this month….

March 25, 2021 by Admin

Adders emerge from brumation in March and April and begin breeding shortly after. Rival males compete for females by performing a dance-like duel where they rise up and wrestle each other to the ground. Although this is an aggressive behaviour between two males, it can look very elegant and is sometimes mistaken for a courtship ritual.

Females incubate eggs internally and ‘give birth’ to live young. They will sometimes mate with multiple males in a breeding season, and some years will not breed at all if conditions are not right.

Adders are venomous, but their bites are rare and generally not serious. They are shy and will only bite as a last resort if threatened. Saying that, adder bites are most common at this time of year. This is because they can be particularly sluggish as they emerge from brumation, and if they are approached by a person or animal and unable to escape quickly enough, they may resort to biting. This can be avoided, however, if we don’t try to approach or handle them.

*Male adders are grey or silver along their sides, unlike females which are brown (Photo: Matt Wilson).*

What our animals are doing this month…

January 27, 2021 by Admin

By mid-late February, the first palmate newts will start emerging from their overwintering sites and making their way to breeding ponds, where the breeding season will continue throughout spring until the end of May.

Males typically arrive at ponds first where they perform a courtship display to attract females, involving some vigorous tail shaking. Males then drop a spermatophore which the female picks up via her cloaca, using it to fertilise her eggs. She lays her eggs one at a time, carefully rolling each one in an individual leaf. Although this seems like a slow process, a female palmate newt usually lays between 100-300 eggs per season.

If you’re looking for palmate newts they can be tricky to identify as they are easily confused with smooth newts, but the key difference is that smooth newts have spotty throats whereas palmate newts do not. Males in the breeding season are easier to tell apart as male smooth newts develop a crest along the back, and male palmate newts develop large webbed hind feet and a small filament at the tip of the tail.

Croaking Science: Courtship & Reproductive Behaviour in Newts and Salamanders

March 27, 2017 by Admin

Courtship and reproductive behaviour in newts and salamanders

Courtship behaviour in newts and salamanders is very different to that of frogs and toads (anurans). In anurans, fertilisation is external so the male expels his sperm whilst the female lays her eggs. However, in newts and salamanders, fertilisation is internal. The male deposits a sperm package, the spermatophore, and the female uptakes this into her reproductive tract to fertilize her eggs. Male newts and salamanders have evolved a range of complex behaviours to encourage the female to uptake the spermatophore. This may involve contact between the male and female, but in aquatic newts of the family Salamandridae, there is no contact and the male encourages the female through complex courtship displays.

male showing belly Matt Wilson spring11 — Great Crested Newt ©Matt Wilson

Newts in the genera Triturus (e.g. great crested newt) and Lissotriton (e.g. smooth newt), have similar courtship displays. During an initial orientation phase, the male will move in front of a female and attempt to gain her attention. The female may show no interest and swim away. If successful, the male moves into a static display which involves intense tail fanning and wafting pheromones towards the female. Once the female is fully engaged the male will start to retreat backwards facing the female, still tail fanning. He will then turn around, creeping away from the female with his tail quivering and her following. The male will pause, deposit his spermatophore onto the substrate, walk one body length forward and stop, turning 90 degrees. This allows the female to move so that her cloaca is directly over the spermatophore. She now uptakes the spermatophore for successful fertilisation. Unfortunately, spermatophore uptake by the female will not always be successful so the male has to perform the courtship display from the beginning.

Although males will develop secondary sexual characters during the spring (e.g. tail crest, webbing on the feet), the courtship display takes place in underwater in darkness, so visual cues are likely to be irrelevant. Recent research has shown that the courtship pheromones produced by the male are crucial in ensuring mating success. When a male employs tail fanning, he sends sex-specific pheromones towards the female and these directly impact her responses. In the laboratory, female palmate newts (Lissotriton helveticus) exhibit all the sexual responses up until spermatophore uptake, when in the presence of male pheromones, but no male present. This demonstrates the importance of pheromone production and effective transfer to the female during mating. Previous research has demonstrated that male newts which perform their displays more energetically, have higher mating success. In addition, in male smooth newts (L. vulgaris), males with higher body mass and crest height achieve higher mating success, possibly due to enhanced pheromone production and more effective transfer to the female. This research demonstrates the importance of effective transfer of pheromones by the male towards the female for reproduction.

Male pheromones may have additional effects on females. In the aquatic Spanish ribbed newt (Pleurodeles waltlm), which has both contact and non-contact displays, the male has special glands in the cloaca. When these are released they induce the female’s cloaca to expand and uptake the spermatophore. It has previously been thought that the female doesn’t have a choice over whether she receives the spermatophore from a particular male, once he has clasped her and released his pheromones. However, recent research has demonstrated that females of this species may exhibit thanatosis (feigning death) during courtship prior to the crucial moment of pheromone production by the male. This avoids spermatophore uptake by the female and therefore may provide an escape strategy by a female, should she not want to be persuaded by the male to mate. Thanatosis has previously only been known as an escape strategy by amphibians and has not been observed in a sexual context.

Male newts and salamanders exhibit a range of complex sexual displays. Although many of the behaviours exhibited are widely understood, there are still areas where we have less understanding, such as the effects of pheromones, importance of secondary sexual characters and female choice in mate selection.

References

Halliday, T. R. (1974) Sexual behaviour of the smooth newt, Triturus vulgaris (Urodela, Salamandridae). Journal of Herpetology, 8 (4): 277-292.

Green, A. J. (1991) Large male crests – an honest indicator of condition, are preferred by smooth newts, Triturus vulgaris (Salamandridae) at the spermatophore transfer stage. Animal Behaviour, 41 (2): 367-369.

Janssenswillen, S. & Bossuyt, F. (2016) Male courtship pheromones induce cloacal gaping in female newts (Salamandridae). Plos One: DOI:10.1371/journal.pone.0144985.

Teyssedre, C. & Halliday, T. (1986) Cumulative effects of male’s displays in the sexual behaviour of the smooth newt, Triturus vulgaris vulgaris (Urodela, Salamandridae). Ethology, 71: 89-102.

Treer, D., Bocxlaer, I.V., Matthijs, S., Four, D. D., Janssenswillen, S., Willaert, B. & Bossuyt, F. (2013) Love is blind: indiscriminate female mating responses to male courtship pheromones in newts (Salamandridae). Plos One, 8 (2): e56538.

courtship

Footer

Contact us