| 1 | Checkered keelback |
The checkered keelback is believed to be the most common snake in India, out of well over 200 species. It’s a water-loving species which is found in rice paddies, rivers, lakes, drainage ditches and manmade ponds. One reason for their success is that checkered keelbacks lay an extremely high total of eggs. The typical range is 30-70, and there’s various reports of over 100 per batch. Other figures mentioned are 8-88 and 8-91, making this a state of the art egg layer either way.
No matter how many hatchlings get picked off by storks or crocodiles, there’s always another influx to take their place. The highest total of all time, and one of the highest for any snake, was a batch of 120 newborn checkered keelbacks from the Anand District of Gujarat, India, reported in 2018.
Checkered keelback eggs average at 1.8 x 2.7cm, and are laid in March and April. Mothers have to be stealthy to prevent the eggs from being swallowed up, and their favourite laying sites include termite mounds, crevices in wells, and rotting vegetation. Mothers are also somewhat caring, as they stay with their clutch of eggs post-laying, during the incubation period of 37-60 days.
| 2 | Mud snake |
Living in water has a close correlation with egg totals, as the quantity of predators is particularly vast. The mud snake (Farancia abacura) lives in southern US states like Florida, Georgia and Louisiana, and mainly inhabits stagnant waterbodies such as swamps, straying to land during heavy rainfall. They’re no threat to humans, and face many predators in their swamp habitats, including American alligators, cottonmouths and racoons. Their solution is to lay a huge amount of eggs, and mud snakes hold the official record for US snakes, at a maximum of 111 eggs laid. The totals are highly variable, with as little as 4 per batch, but are usually in the dozens.
Part of this is length, as Farancia abacura is one of the USA’s longest snakes at a record of 207.0cm. Yet they lay far more eggs than the actual longest, the bull snake (record 267.7cm), at an average of 5-19. Like the checkered keelback, water is a huge influence.
Mother mud snakes were once thought to zealously protect their eggs, but this turned out to be false. When researchers drew near, mother mud snakes hid their heads in their coils. When one researcher reached out to touch an egg, the mother fled by breaking through the nest material and vanishing.
| 3 | Jararacussu |
In snakes, length has a close, though not exact correlation with size. The largest common garter snake mothers will lay over 40 eggs, while small mothers will lay just 20, and this rule also applies within families. Out of 30 Bothrops lanceheads inhabiting Brazil, the jararacussu is the longest at a maximum of 2.2 metres. It’s also the most prolific breeder of the lot, producing an average of 13-40 live young per session, and a confirmed record of 73.
This shock and awe breeding strategy has also led to huge gender size disparity, with females up to twice as large as males, at an average to 2 metres versus 1 metre. Jararacussus are a creature of dark, thorny forests in eastern Brazil, including along the Atlantic coast near Rio de Janeiro. Locals are terrified of these tangled forests, and for good reason, as jararacussu venom can unleash swelling, extreme pain, and severe kidney damage.
As larger females lay more eggs, it’s likely that jararacussus are caught in an evolutionary spiral whereby growing continuously larger increases their survival chances. In 500,000 years, they could be bigger still, pushing to 2.5 metres. Like all Bothrops lanceheads, this species lays live young rather than eggs.
| 4 | Boa constrictor |
One of the world’s most common snakes, and one of the most prolific birthers. These facts surely have some connection to each other, but either way, the record number of young per batch was 63, while the average is 25.
Boa constrictors occupy every country in South America except Chile, and can live an estimated 40 years. Their habitats are flexible, including grassland, jungles and agricultural areas. Combine this with 30+ babies annually, and you have a perfect recipe for continent-wide domination. Babies are independent instantly, with no maternal care, and measure 35-50cm, versus 2-3 metres for an adult.
At one point there was great confusion, as this 1985 paper discussed how northern colonies had much smaller litters. Those from central America (Costa Rica, Honduras) had totals ranging from 10-36, while those from South America (Brazil, Bolivia) ranged from 6-63. The difference was vast. What they didn’t realise then was that Central American boas are actually a different species called Boa imperator, which was separated off in 2009. Not all boas are massive breeders, as the ringed tree boa averages at 13 per litter.
| 5 | Puff adder |
Being long is one way to fit dozens of eggs inside you, but so is being exceptionally thick. This is what the puff adder of sub-Saharan Africa accomplishes. Puff adders are a decent length of 1-1.2 metres, but are more renowned for their crushing heftiness, which they use to pounce on passing rodents and inject a powerful cytotoxic venom.
Along with gaboon adders and east diamondback rattlesnakes, puff adders are the thickest non-constrictor, and this allows for an average newborn total of 40-60, laid every couple of years. Puff adders may hold the absolute record for a snake litter, at 156, produced by a Kenyan female in a Czech zoo.
Like the boa constrictor, puff adders are extremely widespread, occupying all countries south of the sub-Sahara desert. Their huge egg totals are doubtlessly involved. Puff adders also have a particularly long gestation period, at 7-9 months, and occasionally over a year. Courtship is gruelling in the puff adder world, and males will wrestle to secure the females’ affections. Seven males have been spotted following a single female.
| 6 | Brown watersnake |
The Nerodia watersnakes have 10 members in the USA. All are non-venomous, all lay live young, and most have a high total per litter. Chief among them is the brown watersnake (Nerodia taxispilota), which inhabits reservoirs, lakes ands streams alike. A 1985 report produced data from two locations. Brown watersnakes from Chesterfield County, Virginia laid 19-63 live young per batch, while those at a Savannah River site in South Carolina produced 7-63. There was little difference by state, but most importantly, the totals were huge.
Confirmed predators of the brown watersnake include American alligators, eastern racers, American white ibis, cottonmouths, great blue herons, snapping turtles and racoons. If each of these predators eat just two brown watersnakes from each litter, then the species would be in serous trouble – if they laid a normal sized litter, that is. A litter of 5 would cause them to go extinct, but a little of 50 gives them wiggle room, a flexible cushion.
Brown watersnakes are a common species in the US south, including in Louisiana, Florida, Georgia, northwards to Virginia. Another family member is the diamondback watersnake (Nerodia rhombifer), found in the central US. This lays 13 to 62 live young.
| 7 | Fer-de-lance |
The deadliest of the Bothrops pitviper family, with a cytotoxic venom that causes life-changing amputations. Even worse, this species lays the most babies at once, producing a whole new team of fer-de-lances ready to cause chaos in central America. An old 1985 report found that fer-de-lances from Costa Rica produced 48-86 younglings per batch. Those from Panama/Honduras produced 32-71.
These newborns measure 28-35cm, and weigh just 7-13 grams. The average adult measures 100-120cm, reaching a maximum of 2.5 metres and achieving a weight of 6kg. How many babies they produce varies strongly by region. One study took place entirely within Costa Rica. It found that on the northern Atlantic side, they gave birth in September-November, with an average litter size of 41.1, and a range of 8 to 86. On the southern Pacific side, the average was far lower at 18.6, with a range of 8-40. Here, they give birth earlier, in April-June.
Another baby factory is the common lancehead (Bothrops atrox) of south America, but this reaches a maximum of 56 – close but no cigar. The Bothrops pitvipers aren’t uniform baby machines. Species like the Brazilian cerrado lancehead (Bothrops pauloensis) produce just 4-10 neonates per session.
| 8 | Indian cobra |
Cobras aren’t famed for their high egg totals, as the red spitting cobra lays a moderate 6-21 per batch. India cobras aren’t stratospheric, but according to a 2021 report, they may be the most prolific egg layer of their family. Scientists reacted to a distress call in Alappuzha District, Kerala state, and discovered a 1.5 metre long cobra sitting on an unusually large pile of eggs, near brick rubble. Counting by hand revealed a huge total of 45 small white eggs, of which 3 were badly damaged.
Before this, the record egg clutch was just 32. The average for an Indian cobra is 10-24. The scientists were cautious, and speculated whether this was a communal nest, the combined eggs of two mothers, but no Indian cobras have ever been observed to nest together (unlike some rattlesnakes). Therefore a great new record was established. Monocled cobras in Thailand are also decent egg layers, producing an average of 23.5 eggs per clutch.
| 9 | Common garter snake |
The humble common garter snake (Thamnophis sirtalis), virtually ubiquitous across the USA, is famous for gathering in writhing colonies of up to 1000 in order to preserve winter warmth. But they also lay a huge amount of babies, with several batches of over 80 being recorded. Most litters range from 10-40, and over 50 isn’t exceptional.
One researcher found that the litter size was highest in Ohio and the surrounding states, at a latitude of 40 degrees, as these had the perfect habitat for Thamnophis sirtalis. In extremes of cold and warmth, like the Californian west coast or central Canada, the litter size was significantly smaller.
At birth, common garter snakes measure 12-23cm, before reaching 60-100cm in adulthood. Their colours are mostly the same as a youth, just becoming slightly duller. They tend to give birth in late summer, and favourite spots to produce this baby batch include burrows, cracks in walls, and below rock piles. Common garter snakes have no instinct for maternal care, and abandon their babies immediately.
| 10 | Burmese python |
The Burmese python is Florida’s number one invasive species. Since escaping from zoos in the 1990s, they’ve somehow ballooned to an estimated total of 300,000, most of which are found in the swampy everglades. They’re proving impossible to eradicate, and a reason for this extreme takeover is the colossal amount of eggs they lay. At 5 to 6 metres, Burmese pythons are part of the top 10 longest snake species, and their vast egg totals are a mirror image.
In 2022, scientists captured a Burmese python measuring 5.4 metres and weighing 215 pounds, the heaviest snake ever recorded on US soil. Officials announced that 122 eggs were found inside its belly. July 2023 saw a slightly different record, as a Burmese python was found protecting a nest of 111 eggs, the most found outside the species’ body.
Compared to cobra eggs, a Burmese python’s are yellower in colour and aren’t as elongated. Some of them resemble small jagged rocks rather than eggs. Burmese pythons are more caring mothers than most, curling around eggs and shivering to increase their temperature.