JP/W raptor nesting thoughts

Some speculations on Jurassic Park Velociraptor nesting and pack composition, mostly based on the two JP sequels, in which we see raptor packs that are living in the wild and confirmed to consist of animals of more than one sex.

(spoilers for twose movies, and for the other JP/W ones a bit as well)

I've concluded earlier that each sequel possibly features two female raptors, and that with JP3 it actually looks certain that it does. Most of the raptors seen (clearly) on screen are males, though. How representative is that of the packs in general?

I assume there are at least more females than those two in the JP3 pack considering how many nests we see side by side. I count at least 4 nests panned to without a cut, plus the one right in front of Dr. Grant, and 2 more if the nests seen in the shot where Billy walks in aren't some of the same that were already shown, which, judging by where Dr. Grant turns to look, they aren't. So 7, with a lot of eggs in each.

The ratio of pack members of different sexes doesn't have to be 1:1, and one female laying several clutches with different fathers, with the males incubating their respective clutches, is behavior seen in some modern birds. But then again, at least in the birds I know of doing that, the female doesn't participate in caring for the eggs or hatchlings at all, and the JP3 raptor females obviously care quite a lot about what happens to those eggs. Capturing Blue to be the next Indoraptor's mother would be pretty stupid if parenting was something only male Velociraptors do, wouldn't it (not that a lot about the Indoraptor project wasn't pretty stupid anyway).

Laying that many eggs also takes time, if JP Velociraptors produce eggs similarly enough to modern birds, which can lay about one egg per day at the fastest - an example from the faster end of that spectrum being domestic chickens, which, despite having been selectively bred for egg production, can't lay a 10+ egg clutch at once. There is the possibility of them perhaps at least being able to lay two eggs at a time: modern birds have only one functioning oviduct and ovary, while oviraptorosaurs Citipati and Gigantoraptor seem to have had two, based on that eggs in their nests that have been found are arranged in groups of two rather than as a cluster, so it's not unheard of in Mesozoic maniraptorans, though apparently troodontids also had only one, meaning that at least their and birds' common ancestor had already lost function in one ovary and oviduct, not sure where dromaeosaurids stand in this. (For what it's worth, only two of the JP3 nests where I can count the eggs have an odd number, and those could perhaps be explained with humans not being the first to steal their eggs, and one of the nests with an even number does kind of look like the eggs might be arranged in twos, though not very clearly and the others look more like clusters, but it's hard to say without seeing them directly from above. So, regardless of how it was for real dromaeosaurids because this is still a fictional animal - eggs one or two at a time for JP/W Velociraptors? Not sure.) Either way, even with two eggs per day, each of those clutches would still take several days to complete laying.

Ftr this is the nest where the eggs kind of look arranged into pairs.

The nests would be at very different stages of incubation if all of the eggs had been laid by only two females, and at least some of them should probably have a parent brooding them at the moment the humans wander in. That there isn't a raptor sitting on any of the nests looks to me like JP Velociraptors practice delayed incubation like many modern birds do, where in the early stages the eggs are left uncovered for extended periods, so the eggs laid first develop slower and hatch around the same time as the later ones, instead of the oldest and youngest hatchling in a clutch having maybe over a week's age difference. In which case all the nests would be at about the same incubation stage. In which case each nest would have a different mother.

Two Bald Eagle (Haliaeetus leucocephalus) chicks at less than a day old. The eggs were laid four days apart, but the younger eaglet hatched less than two hours after the older one. (link to nestcam)

It seems likely to me we don't meet the whole pack in either movie. In JP3 some of the pack would have to have skipped joining in on the human chase, to stay and guard the eggs that weren't stolen, and in TLW the raptors may have their home elsewhere in the area and just hunt in the grass field and the village, and the rest of the pack is wherever that is. Or the long grass could be their home, but perhaps not everyone bothered to get up to hunt. Since JP Velociraptor seems to be a species with females being dominant in their social structure, the "one girl per team" pattern could indeed be because each female is the leader of their respective hunting/searching team.

Is all the members of the team except for the leader being males the norm? Well, we can't actually say for sure how many of the group of raptors seen in the long grass scene are male or female, other than that at least one is male.

Getting ready for his big moment.

The most raptors on screen at the same time in JP3 is during the egg returning scene, with one female and four males. The group Eric saves Dr. Grant from is one female and three males. Are these different groups? Or is one male missing from the earlier scene because he's with the other female, having just finished killing Udesky, and the total number of raptors that went after the humans is two females and only four males? Seven males would match the number of nests seen, but not every male in the whole pack needs to have gone after the humans, so it could also just be four, with the only one who's turned back and gone home by the time of the final confrontation being the other female.

Four could also be the total number of adult males in the pack, if JP Velociraptors aren't strictly monogamous - no clear evidence for or against them being so in the movies so far - since two large clutches at the same stages of incubation sharing a biological parent is a lot more feasible if it's not the parent laying the eggs (I've featured one such trio in my JP fanworks myself, and they did have two clutches to incubate simultaneously - for a trio of two males and one female nesting together there would more likely be one clutch, with each male being father of some of the chicks, for which I can provide an example in the form of another Bald Eagle nest). The pack could also include non-breeding individuals, such as subadults staying with their parents' pack. But if each nest does indeed have a different mother, then it seems that more females stayed home than went after the humans, and with males it's probably the other way around.

This might be out of temporary necessity, and at other times the team composition could be different. The JP3 raptors, as established, are currently nesting. If the eggs weren't being incubated because more eggs are still coming, the females whose clutch isn't complete may not want to wander too far from their nest, whether or not they will be the ones to do all/most/any of the incubating. Wouldn't want to end up going into labor on the other side of the island.

Counting the eggs in the nests shown on screen again, one has 13, the others have 12 or 11, and I can't tell for sure about one that's farther away from the camera and blurry. Clutch sizes in modern birds can vary within a species between individuals as well as seasons for the same individual, but the birds do also seem to know when they aren't done laying. If 13 (or 14 with one egg already having been lost for some reason, if the eggs come in pairs) is a full clutch, at least some of the others probably aren't yet. And I guess Billy took two from the nest with the most eggs in it, thinking their absence wouldn't be noticed, as one more example of underestimating the raptors.

Peter Ludlow: Velociraptors. Our infrareds show their nesting sites are concentrated in the island's interior, which is why we planned to keep to the outer rim.

While it's very obvious the JP3 raptors are in the middle of nesting during the movie's events, I suppose it's possible the raptors in TLW are, too. If the time of the year makes a difference for them at that, well, rexes and stegos as well as some other dinos seem to be having babies at the time, so I'd say 'tis the season if there is a season (and in JP3 the Pteranodons are also nesting at the same time as the raptors).

Roland Tembo: It's the rex nest. Infant's probably only a couple weeks old. Never left the nest. Offspring that young, the parents won't leave him alone for too long.

There's also a baby Triceratops and what look like juvenile Pachycephalosaurus in the herd the hunters find on the game trail. And Dr. Harding did want to study in particular the animals' nesting behavior when going to the island.

Dr. Sarah Harding: Those animals that just walked by, did you see them? It's a family group, a pair-bond and a sub-adult, long after the juvenile was nest-bound. Every egg clutch I've seen has got shells crushed and trampled. The hatchlings definitely stay in their birth environment for an extended period of time, that's conclusive. I can put that controversy to rest if I can just get a shot of the nest. [...] I'm trying to change a hundred years of entrenched dogma. Dinosaurs were characterized very early on as vicious lizards. There's a great deal of resistance to the idea of them as nurturing parents. Robert Burke said the T. rex was a rogue who would abandon its young at the earliest opportunity. I know I can prove otherwise.

John Hammond: Paleontological behavior study is a brand new field, and Sarah Harding is on that frontier. Her theories on parenting and nurturing amongst carnivores have framed the debate.

This could explain why they just (try to) kill all the humans they see, even with how difficult the main character trio proves to catch, when for food that's probably not necessary. Nesting animals can be especially territorial (which I've already used as a possible explanation for one instance of seemingly senseless raptor violence, so, there could be a precedent). And, I guess being a mess of hormones could be a factor in their getting snappish at each other at the drop of a hat, too. That they channel their restless energy so destructively is probably still due to less than ideal socialization, but perhaps there's extra restlessness to deal with right now.