Plan to Attend the 9th Annual Field Day Rolling Plains Quail Research Ranch Friday, Sept. 30
Plan to attend the 9th Annual Field Day Rolling Plains Quail Research Ranch Friday, Sept. 30, 9 a.m. – 3 p.m. This year’s theme, “Can we “insulate” this bumper crop of quail?” CEUs will be offered at the event (2 CEUs; 1 General, 1 IPM). Click here to see agenda for more details.
Determining Optimal Levels of Brush Cover for Northern Bobwhite in the Rolling Plains by Brad Kubecka, Graduate Research Assistant
Landscapes that support high densities of northern bobwhite consist of an interspersed mixture of woody and herbaceous cover. Maximum bobwhite densities may be achieved within some range of these cover types, a concept known as “slack.” Thus, landscapes with 10% vs. 40% brush cover could potentially support comparable densities of bobwhites. Recent research in South Texas suggest that landscapes with greater amounts of brush express less variation in the relative abundance of bobwhites during wet and dry years (Parent et al. 2016). In other words, woody cover seemed to cushion bobwhite populations during drought years and/or suppress expansion during wet years. Our objective is to examine associations of bobwhite abundance, woody cover metrics, and precipitation in the Rolling Plains of Texas.
Our study is being conducted on the Rolling Plains Quail Research Ranch (RPQRR) in Fisher County, TX using trapping data (n = 296 traps) collected from November 2008 to March 2017. We feel our intensive trapping database will provide a more in-depth approach than previous studies that have used spring cock call counts as a gauge of landscape configurations and bobwhite abundance. We will calculate relative abundance at each trap site (no. of unique individuals trapped) and quantify woody patch metrics surrounding trap sites (within the buffer of bobwhite’s home range at RPQRR) using satellite technology. Precipitation data will be obtained from on-site weather stations. Our goal then is to determine the influence of woody cover, precipitation, and their interaction on bobwhite relative abundance. Our expected results will provide land managers with an estimate of optimal woody cover and configuration for high densities of bobwhites in the Rolling Plains for both wet and dry years.
Let’s do a quick demonstration. Consider the photos to the right where green represents woody cover and the plot size represents 40 acres (400m x 400m). At this scale, woody cover in all plots is within average flight distance of a bobwhite in the Rolling Plains. Which of the photos has more brush? Which has more edge? Does it matter? Which landscape would consistently hold more bobwhites? During dry years, will areas with fewer, but larger mottes of woody cover sustain higher bobwhite densities? Bobwhite managers often spend much money “sculpting” such patterns (e.g., mottes, strips) on large scales. Through our satellite technology and trapping data, we hope to answer these questions and “tighten” our range of accepted slack. (All photos are drawn to scale and have equal amounts of woody cover. Total woody edge for the strip patterns is 64 units, mottes 15, and sculpted is 51.)
Scaled Quail Restoration to Historic Ranges in the Rolling Plains: Project Update by Becky Ruzicka, Ph.D. candidate
We wrapped up the most intensive part of our monitoring for the year during August on the Knox County translocation site. Since April we have been monitoring our radio-collared hens daily, collecting information on their survival status (i.e. live or dead), movements, and nesting activity. From this point forward we will transition to a bi-monthly monitoring schedule. This will allow us to continue to monitor survival and movement through the fall, albeit at a courser scale. We also plan to conduct trapping to band juveniles, take feather samples for genetic analysis, and potentially document abundance on the two release sites (if our capture rates are high enough).
As it stands now, our survival is at 60% for breeding season. If you were really paying attention, you’d notice this survival percentage is slightly greater than the one I reported in last month’s e-Quail (no, there aren’t birds back from the dead!). We were actually able to locate some of the birds that had been missing and found that they were still alive, thus a slight increase in our total survival as they were added back into the sample. Our farthest recorded dispersers travelled a distance of 5 miles, however most (~70%) stayed within one mile of their release site. Overall, the birds have spread out over an area of approximately 35,000 acres. A formal analysis of these data will be forthcoming in which I will evaluate survival and dispersal as a function of our soft-release and ecoregion source treatments.
Although we are still in the beginning stages of this project, I wanted to take this opportunity to thank the large number of individuals and organizations that have contributed money and resources thus far. I would especially like to thank my field crew: research assistant Drew White, technician Carolin Tappe, and intern Bekah Mullen. Starting in February of this year these ladies have been instrumental in trapping and translocating 388 quail, conducting an occupancy survey over 100,000 acres, and amassing a database of over 4,000 unique observations on our radio-collared birds. Well done!
Double Clutchin’ by Brad Kubecka, Graduate Research Assistant
Q: “I’ve been seeing a lot of big broods. Are the birds on their 2nd or 3rd hatch right now?”
A: Well …
First, it is important to distinguish the difference between 2nd, 3rd, and 4th nest attempts and 2nd or 3rd broods (i.e., successful, successive clutches). An average from 2009–present RPQRR data suggest about 12% of radio-collared bobwhite hens attempt a 2nd nest and a small handful attempt a 3rd or even 4th. There is much variation about this estimate for logistic and biological reasons. For example, perhaps a nest is depredated before being found or reproductive vigor is depressed for a particular year. In 2015 nearly one-third of our radio-collared hens attempted > 1 nest, but in 2011 none attempted a 2nd nest (few even attempted 1 nest)
A question of probability
One way to describe the truth to our question lies in probability. Our question now becomes “what is the probability of a hen having 3 successful hatches?” A few parameters we might use to answer this question are 1) proportion of hens that lay a nest, 2) nest success, and 3) proportion of hens that re-nest after successfully hatching a prior clutch. When we calculate this probability, the product is multiplicative. For example, the probability of rolling a 6 on a die is 1/6, but the probability of doing it twice in a row is lower (1 in 36). Likewise, if the national average for bobwhite nest success is 28% (Rollins and Carroll 2001), the odds of having 3 successful nests is much lower (.28 x .28 x .28 = 0.022). Now consider factoring in the proportion of hens that even attempt a 2nd or 3rd nest after a previously successful hatch. And perhaps 20% of hens are killed while nesting. When we keep factoring in all the parameters, we find that the probability of a hen actually having 3 successful nests is very, very low. So where do all the big broods come from?
Putting it all together
We now know 1) not all birds attempt > 1 nest per season, 2) nest success is relatively low, 3) the probability of multiple successful nests is even lower, and 4) as an aside, chick survival is also relatively low. When we see large broods, other dynamics are likely in play. Some of these dynamics such as brood amalgamations have been discussed at length in previous newsletters.
RPQRR Quick Facts for Nests, 2009-16 ( ± SE)
Average Clutch Size: 12.8 ± 0.3
Hatchability (average % of eggs that hatch / clutch): 88%
Nest Success (%): 60.1 ± 3.7.
A New Way to Look at Quail Habitat
It’s called “density gradient modeling.” Think of it as a radar image depicting thunderstorm intensity. In this case being “in the red” is a good thing. Recently John Edwards, a PhD student at Texas A&M University-Kingsville conducted helicopter counts at RPQRR and 3 other area ranches to construct maps illustrating the spatial distribution of bobwhites across the property. The counts at RPQRR are part of a CKWRI research project studying the effects of habitat, climate, and raptors as factors in the quail decline. The map depicted here is a density-gradient map, which uses the covey-detection information provided from the survey such as covey size and location plus additional habitat variables to create a map of bobwhite density across the property. This allows us to evaluate bobwhite density spatially across the landscape. RPQRR’s Brad Kubecka, who is currently pursuing his MS degree at TAMU-K under Dr. Hernandez and me, will be analyzing similar data to better understand how habitat factors (e.g., brush density) affects such density-gradients over the course of the past seven years. Stay tuned; neat stuff.
Operation Idiopathic Decline: Search for the Smoking Gun
The role that disease and parasites may play in quail dynamics has been largely ignored since the 1920s. After the (in our opinion) inexplicable decline of quail in the Rolling Plains, the Board of RPQRF “got serious” about disease and funded a comprehensive project dubbed “Operation Idiopathic Decline.” Currently (as of Feb 2014), the RPQRF has invested $3.4 million into this ground-breaking study of disease and parasites. This webisode explains OID in more depth.