Texas Quail Index 2014 Summary: Part II

This is a continuation from TQI 2014 Summary Part I; you can find the first installment here.  

Texas Quail Index teams finished up their final spring call counts in June.  Next we had them move on to the most labor intensive task in the whole project: dummy nests.  Dummy nests are an excellent instructional tool for helping people learn about what makes up quality nesting habitat.  A dummy nest is simple enough; it consists of three chicken eggs and a small flat washer (You can learn more about them in a video here). The purpose of establishing dummy nests is an attempt to mimic a quail’s nest – and most importantly the teams were forced to mimic quail hens’ in their nest selection when they placed the dummy nests. By mimicking actual quail nests teams learned first-hand the habitat characteristics that make up a successful nest. Teams were required to place a total of 24 nests on their properties, walking 4 separate lines looking for suitable nesting cover in which to place their nests. They also recorded what type of nesting substrate they used: grass, prickly pear, or yucca. Within a 28 day period they checked the nests twice and recorded whether they were depredated or not. Teams also recorded what species of predator they thought depredated the nests based on the eggshell fragments left at the scene and the total number of suitable nesting clumps per acre at each location. 

AgriLife personnel placing dummy nests
in Dimmit county. 

Overall the average dummy nest success across the state was 54%, but it varied greatly ranging from 5% in Dimmit County all the way to 100% in Archer County.  An approximate rule of thumb with dummy nests is that dummy nest success over 40% indicates that the quality of nesting habitat and the predation pressure on site are not likely to be limiting for quail. That’s a rough estimate for sure and there are a lot of variables that go into dummy nest survival rates – including the nest site selection skills of the person setting nests. As a result, the connection between the biological processes at play and dummy nest survival is a tenuous one at best and it makes the data tricky to interpret. For instance, if you record 50% survival of dummy nests you can’t reliably extend that survival rate to actual quail nests on the property by projecting that real nest survival was 50%.  But, that doesn’t mean that dummy nests are not a useful tool.  

The biggest benefit to implementing dummy nests is that it forces you to give the nesting cover on your property more than just a “windshield evaluation.” Too often we (wildlife professionals are just as guilty, if not more so than private landowners) evaluate the land without ever leaving the truck. That’s going to give you a really skewed impression of the actual habitat quality. This year we had an interesting situation with nesting cover across the state. Many teams commented that they thought the nesting cover was excellent before they set the dummy nests. However, when they set the dummy nests they realized it was harder than they thought to find good concealment for their nests. The reason being, that many areas had received near normal rainfall after years of extreme drought. While the bunchgrasses had responded well to that rainfall, they were still suffering from the prolonged stresses of drought and were not as thick in diameter and robust as they needed to be to provide good concealment for quail nests. Looking across the pasture from the road, nesting cover looked excellent, but it wasn’t until the teams started looking down and viewing the world through the quail’s eyes that they understood what was really going on.

The statewide dummy nest data did provide us with some interesting results on the differences in survival between nesting substrates (e.g. grass vs. prickly pear).  The average survival of nests placed in grass substrate was 44% compared to 85% for dummy nests situated in prickly pear. It is well known that quail use prickly pear as a nesting substrate even when bunchgrasses are not limited (Hernándezet al. 2003). Researchers theorized that prickly pear provides a certain measure of mechanical protection and, in fact, found that to theory to be supported after conducting a study using captive raccoons to compare survival between grass nests and prickly pear nests (Hernández et al. 2009). Nests that were placed in full coverage prickly pear survived at a much greater rate than those placed in grass (86% compared to 3%).

Dummy nests are a measure of the combined influence of the quality of nesting cover and the predation pressure on site. Estimating the number of suitable nesting sites per acre gives us an idea of the nesting cover quality, but to understand the predator context requires a bit more reconnaissance. That’s why we purchased game cameras – two for each team – to use in monitoring the predators on site. Teams set-up the cameras on posts next to secondary ranch roads and monitored predator traffic during the nesting season. We recorded the species richness (number of different predator species observed) and the visitation rate (number of times a species was observed) for each site. 

Bobcat captured in Matagorda County. 

Like the dummy nest data, the results we received from the predator monitoring varied greatly among the sites. On some sites we observed no predator species during the monitoring and on other sites we observed as many as 7 different predator species, including hogs, coyotes, raccoons, skunks, armadillos, bobcats, opossums, and badgers.  The most commonly photographed species were hogs and coyotes. We have to be careful, however, in making comparisons of relative abundance between species. Large animals capable of covering large amounts of territory in a single night (e.g. hogs and coyotes) are probably more likely to show up in game camera photos. Even so, we observed an interesting relationship between observations of two predator species.

Hogs making use of a watering hole in Garza County.

Of the 6 sites where both raccoons and coyotes were photographed, we observed an inverse relationship between raccoon and coyote visitation rates (Table 1). On sites where we observed more coyotes, there were fewer raccoons and vice versa. This was noteworthy because of what is known as the mesopredator release hypothesis (MRH) in ecology. MRH basically states that as the top predators (e.g. coyotes) are removed from a system it allows the mesopredators to flourish (e.g. raccoons). Coyotes are in direct competition with raccoons for food and will often kill raccoons when they encounter them. Therefore, as coyote numbers decrease raccoon numbers will increase, according to this hypothesis. This has direct impacts to ground nesting birds such as quail because the mesopredators are typically much more efficient nest predators than are coyotes. So by extension, coyote control may actually represent a net loss for quail. On the Rolling Plains Research Ranch, our own Mark Tyson did his Masters research examining coyote diets. Out the 1,080 scats he collected only 2 scats that contained traces of quail remains (Tyson 2012). They contained raccoons, skunks, and feral hogs (all nest predators) in much greater percentages than quail. While our TQI data lack both the scope and inference to either prove or disprove that mesopredator release was occurring, it was food for thought and should at least make any quail enthusiast think twice about controlling coyotes on their property.

Raccoon captured at daybreak in Knox County.

Table 1. Raccoon and coyote observations in 6 different TQI counties.

County	Coyote Observations	Raccoon Observations
Baylor	17	6
Clay	26	1
Jones	24	7
Matagorda	20	34
Tom Green	7	44
Taylor	6	25