Observations contributed to iNaturalist can be used by researchers and landscape managers for many different types of questions, including studies in natural history, ecology, evolution, and conservation. In 2015, we realized that we could also use crowdsourcing as a way to study mating behavior. At that time, in the entirety of the scientific literature, there were only four dates reported for when Southern Alligator Lizards had been observed breeding. We knew we could get more observations through community science, by crowdsourcing the study of this rarely documented behavior. We started asking people to send us photos and videos of mating pairs, or to upload photos to iNaturalist. We have now accumulated over 850 observations of mating Southern Alligator Lizards, and over 160 observations of mating Northern Alligator Lizards. We are pretty sure that through community science, we have generated the largest dataset ever on lizard mating. This result demonstrates the incredible value of community science for studying rarely observed natural history events.

What does mating behavior look like?
Here are some observations of alligator lizard mating behavior from the last few weeks:
-@tothemax observed this pair in the Santa Monica Mountains on Friday, March 29, just before a storm reached the L.A. area. This pair is likely mating. The male is biting the female on her head/neck region (termed the bite hold), and the male has his tail wrapped beneath the female's tail, which is the mating position.
-@pst207176gear observed this pair in San Pedro on February 29. This is one of two pairs observed by pst207176gear this year. This Feb 29 observation is the first mating observation for L.A. County this year and the second observation across the entire range of the species for this year. Note that they are in the bite hold but not mating in this photo (male's tail is atop the female's not wrapping underneath it).
-@alexak_sd observed a male and female in a bite hold but clearly not mating on March 8 in San Diego.

At what time of year does mating behavior occur?
In the Southern Alligator Lizard, mating activity starts at the southern end of the range, and then sweeps northward and upward in elevation with increasing temperatures. In the southern part of the range, mating activity can start as early as mid-February, but the majority of the mating observations are usually between late March and early May. Mating activity can continue into early June in cooler areas such as in the northern part of the range, along the coast, and at higher elevation.
In the Northern Alligator Lizard, mating activity does not show the same south-to-north pattern. Pairs can be found across much of the species range on any day between early April and early June.

What can you do:

1. Keep an eye out for mating pairs. When in the bite hold, pairs can end up in surprisingly exposed areas like on a lawn, in a driveway, or in the middle of the sidewalk. Sometimes, they stay a bit more hidden, such as on the edge of a shrub, where they can get dappled sunlight throughout the day. In about 5% of observations, the pairs are above the ground in trees or atop walls or fences.
2. Spread the word. The chance of any one person seeing this is quite low, but if you mention this research on Facebook, X, or Nextdoor you will almost certainly reach someone who will see mating behavior this year or has seen it in past years (and if people have photos from past years and know where they took the photo, then we want that observation too). If you want to promote this project, you can send around our project webpage for more info:
https://nhm.org/stories/look-out-amorous-alligator-lizards
Or this YouTube video:
https://www.youtube.com/watch?v=gtUFZMEt1Fw&fbclid=

What have we learned with all these observations? Here are three discoveries so far.

1. Wet years are the big breeding years. The 2015, 2016, and 2018 mating seasons followed below-average rain seasons, and we recorded 30–40 observations of Southern Alligator Lizards in the mating position (i.e., the bite hold). In contrast, the 2017, 2019, 2020, and 2023 mating seasons followed wet winters, and we recorded nearly three times as many observations! In 2023, we recorded 117 mating observations for the Southern Alligator Lizard. So far in 2024, we have recorded 23 observations (as of April 1), and we expect a similar number of observations as last year (110–120).

2. Weather has a huge impact on the timing of the breeding season. Cooler and wetter weather will delay the start of the mating season. The 2023 season is the best example of this. With record rainfall and cooler winter and spring temperatures, the 2023 mating season was roughly one month behind the 2022 season, which was a below-average rainfall year. The 2024 season is following high winter rainfall, so we expect the season to a bit later expect a similar number of observations as last year.

3. Lizards can stay paired up for over two days! In some pairings, the male maintains the bite hold for a long time. Over the course of this bite hold, the pair may mate multiple times. How do we know this? For some pairings, dedicated community scientists check back on lizards repeatedly, sending me photos each time they relocate the pair. We can then learn duration of the pairing. In a few cases, we can use the photos to determine whether they are in the bite hold and mating, or in the bite hold and not mating allowing us to determine if they mate multiple times. To date, we have recorded eight pairs that were together for over 48 hours, and four of these pairs were documented during the 2023 season. One of these pairs was carefully observed by @ginavattuone to be in the bite hold for 54 hrs, 1 minute, the current record for longest duration.

How to participate in this research project?

What to look for? During mating season, males search out females. The male bites the female on her neck or head and may hold her this way for several days. Early in the encounter, the two may engage in a bit of a wrestling match (if you see this, please try to get videos). Sometimes, a second male shows up and we get even more interesting observations! About 9% of all observations involve these threesomes.

When to look? Now through June. For the Southern Alligator Lizard, mating activity is just getting started at the southern end of the range (about half way through in San Diego County and just getting started in Orange and Los Angeles Counties) and has not yet started at more northern and higher elevation locations. For the Northern Alligator Lizard, breeding is also just getting started and should continue through June across much of their range,.

Where to look? Alligator lizards can be found from coastal sand dunes to high elevations in our mountains. And they do better than any other local lizard in urban areas. When in the bite hold, pairs are often found out in the open, on driveways, sidewalks, lawns, and in yards. It is also possible to find pairs several feet off the ground on fences and in shrubs.

How to document? Take photos! If the pair is actively wrestling, please take video as well. We are especially interested in how long pairs remain in the mating hold, so please check back every few hours and search for the pair in the general area. Please upload photos to iNaturalist. If you are in Southern California, please tag observations to the RASCals project. If you are encouraging others to submit observations, they can also email photos to nature@nhm.org. menos ↑