Annual Call for Amorous Alligator Lizard Observations

Our wet winter across the western U.S. is likely to make for an excellent spring mating season for alligator lizards, and, we need your help to study their mating activity.

The Southern Alligator Lizard can be found from northern Baja California to southern Washington, and their close relative, the Northern Alligator Lizard, can be found from central California to southern British Columbia. Within the ranges of these two alligator lizard species are a handful of major museums, hundreds of universities, and thousands of biologists, so you might think we must know everything there is to know about alligator lizards. Unfortunately, like most other species on this planet, we still have a huge amount to learn about the basic natural history of alligator lizards.

Five years ago, we realized that we could use community science as a way to study mating behavior. At that time, there were only 3 dates for when Southern Alligator Lizards had been observed breeding that were reported in the scientific literature. 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. We have now accumulated 255 observations of mating Southern Alligator Lizards, and 37 observations of mating Northern Alligator Lizards. We are pretty sure that through community science, we have generated the largest dataset ever on lizard mating.

What does mating behavior look like? Here are some previous observations of mating behavior submitted to the RASCals project by iNat users @tonyrivard, @samfellows566, and @emilyd47:
https://www.inaturalist.org/observations/21925752
https://www.inaturalist.org/observations/21237128
https://www.inaturalist.org/observations/21987603

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

1. Weather has a huge impact on the timing of the breeding season. Cooler and wetter weather will delay the start of the mating season. If mating activity has already started, then bigger storm systems can shut down activity until weather improves. Normally the first observations of the year are from the southern end of the range, usually San Diego County, and are around the second week of February. Following 2019’s cool, wet February, the mating season started about a month later in mid-March.

2. Wet years are the big breeding years. Although we started this research effort in 2015, people have submitted observations that date back to 2003 (woohoo for digital cameras!). Across these years, what we see are that drier years have reduced breeding activity. For example, the 2015, 2016, and 2018 mating seasons followed drought years or below average rainfall totals, and we received about 30 observations of Southern Alligator Lizards in the mating position. But following the wet 2016/17 winter, we received 87 observations! The 2019 season is only just getting started (all observations are still from the very southern end of the range), and we already have 35 observations, most of which are from early April. We expect many more observations through the 2019 season.

3. Lizards can stay paired up for over two days! The actual act of mating likely takes place shortly after the lizards pair up. However, the male maintains the bite hold for a long time. This is most likely a type of “mate guarding”, in which the male is trying to make sure that no rival males try to mate with the female (but we still have more research to do before we are positive this is what’s happening). But how long might a male maintain the bite hold? This year, two dedicated naturalists, @lemonbee and @molly91945, repeatedly checked back on a pair and observed the lizards together for nearly 49 hours! This is a new record for this species! You can check out one of their amazing observations in this multi-day sequence here:
https://www.inaturalist.org/observations/21425974

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 8% of all observations in our dataset have two males with a female (for example: https://www.inaturalist.org/observations/22333855 ).

When to look? Because we have accumulated so many observations, we now know that the Southern Alligator Lizard mating season can start as early as early February in the southern part of the range and continues into early June in the northern part of the range and at higher elevations. This year, the season is just getting started, and mating pairs should be found in coastal Southern California through early May, with mating in more northern and higher elevation locations throughout May and June. For the Northern Alligator Lizard, breeding has also just started and will continue through mid-June, again with lizards in the south and at lower elevations breeding earlier.

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 mating hold, pairs can even be found out in the open, and are often observed 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, which you can email to me. 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.

If you see courting or mating alligator lizards, please upload photos to iNaturalist. If you are in Southern California, please tag observations to the RASCals project.

Publicado el abril 13, 2019 01:57 TARDE por gregpauly