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A Bird Nest on the Ground by Dr. Dale Rollins
Consider this: if 100 quail eggs are laid in June, how many adult quail would you expect to result from them a year from now? Forty? Twenty? How about five! Here’s the math. Average hatch rate across the range of bobwhites is about 30 percent, so we have 30 chicks hatched. Chick mortality is high, so perhaps 40 percent of those (or 12 birds) live to September. Survival through the winter months might be about 40 percent, so now we have five birds alive come May. And you think you have a tough row to hoe? Eggs attract critters from all corners of the habitat: big and small, lanky and chubby, furred and scaled, feathered and featherless. Most predators are opportunistic, taking whatever prey or food item they happen upon, and few items are more attractive than a nest of quail eggs. Some landowners, quail hunters and (a few) biologists believe that depredation of ground-nesting game birds (e.g., bobwhite and scaled quail) is a limiting factor. Although populations of quail go up and down like a roller coaster, depending on habitat conditions and rainfall, the overall trend for the past 25 years has been downward. Concurrently, predator populations, especially medium-sized mammals like raccoons, appear to be booming in the absence of a fur market, and fueled by our fetish for feeding deer. And how ‘bout them feral hogs, eh Cooter? Is the bullish predator population and the bearish decline of quail coincidental or cause and effect? Objective information about the significance of nest predation is difficult to assemble, as predation is most often conducted under the veil of darkness. Biologists examining pilfered quail nests may ponder "who dunnit?" The list of "suspects" may include armadillos, badgers, bobcats, coyotes, foxes, raccoons, rodents, skunks, various snakes, crows, ravens, roadrunners and perhaps others. And, as if the native predators weren't enough for a nesting hen to worry about, there's also the imported feral hogs and fire ants. And you thought you lived in a tough neighborhood? When a person happens upon a broken nest, the predator's identification is open to speculation. Was it a skunk? What about those coyote tracks in the road? Is that nearby "rooting" evidence from a feral hog? If there are no eggshells present, was the culprit a snake? Sounds like a case for Sherlock Holmes, doesn't it? Cue up the CSI Miami music and put a re-run of “Quincey” in the VCR. Since 1994, I’ve been a student of “CSI Quail.” Early on, I recruited a budding young biologist, Fidel Hernandez, to assist me with these investigations (Hernandez did research for his Master’s degree under my tutelage at Angelo State University; he is now a quail research scientist for the Caesar Kleberg Wildlife Research Institute [CKWRI] in Kingsville).
Our findings were "illuminating." Raccoons were Public Enemy #1 for ground-nesting birds near San Angelo, accounting for over 80 percent of the nest thefts. Raccoons seemed especially fond of "hen fruits", i.e., eggs, and provided us with some especially interesting tales. It was not unusual to find muddy paw prints from inquisitive coons on our camera equipment (which was usually placed three to six feet high in a tree). Once one of the cameras had been removed from its tripod and carried some distance away; it was found with the back of the camera opened and the film stripped out of it! Muddy paw prints suggested who was responsible! At other times, photos showed a guilty raccoon appearing to be hiding his face from the camera not unlike a juvenile criminal hiding his face from the TV news camera. Scientists have a saying: "form ever follows function." Given that, what's the function of the raccoon's black mask? To dull reflections of moonlight off of water? Or perhaps it’s befitting attire for this masked marauder who quail might dub the "king of the nest bandits." Besides raccoons, other nest predators caught with their "paw in the cookie jar" at the San Angelo site included gray foxes, striped skunks, bobcats and opossums. Some unexpected nest predators included turkey vultures, woodrats, golden-fronted woodpeckers and even a tom turkey! Artificial nests at another study site near Albany recorded feral hogs, raccoons and crows as "common thieves." It's also interesting to note that roadrunners, which are often maligned as being "hard on quail nests" were not incriminated during our studies. Roadrunners were photographed at nests on several occasions, but they never destroyed any (chicken) eggs. Also, it's interesting that no coyotes were photographed at nests at the coyote-laden study area near Albany. The ever opportunistic coyote probably accounts for its fair share of nest depredations, so why didn't they get "caught" on our candid cameras? We believe the camera setup is probably "obvious" enough to deter the ever neophobic and often "trap-shy" coyote. We often photographed gray foxes at the San Angelo site, but rarely red foxes which also occur on the study area. Red foxes tend to be much more "coyote-like" in their basic distrust of contraptions than do their gray cousins. We found that egg size affects how often eggshell evidence is left at the scene of a "nest crime." Chicken eggshells were found at destroyed nests about 90 percent of the time, whereas quail eggshells were found on only 3 percent of the occasions. Size matters. Typically, quail biologists label a disrupted nest where no eggshells remained as "snake." However, our data suggested that most predators (and especially raccoons) are capable of destroying quail nests without leaving any eggshell evidence behind. Our cameras never "caught" a snake but the possibility exists that the cameras were positioned in such a manner that snakes might avoid detection. We do not believe this to be the case during our study, as all "break ins" were accounted for by some predator. As a result, we were only able to characterize the depredation patterns (i.e., eggshell evidence) of predators for simulated turkey nests (using chicken eggs as surrogates). Raccoons tended to leave two relatively equal-sized eggshell fragments: the top and base of the egg. Eggshells were typically left within 15 feet of the nest. But eggshell size, condition and distribution often varied, depending on whether the nest was attacked by a single raccoon or a family of raccoons. When a family of raccoons was involved, eggshells tended to be scattered greater distances from the nest, probably as a result of family "squabbles." As nest predators go, skunks are pretty neat eaters. They usually bit the large end of the eggs, leaving a large eggshell fragment—eggshells were usually found within two feet of the nest. Gray foxes were unique—they liked carry-out orders. Gray foxes would grab a whole egg and transport it to a hiding place well away from the nest, where they would either eat it, or cache (bury) it. The eggshells were found more than 25 yards away from the nest. Eating patterns showed a wide opening in the middle-to-lower base of the egg.
Lastly, bobcats are especially "neat and clean" predators, typically aristocratic in their modus operandi. One bobcat was photographed on several consecutive days sitting near the nest, but not eating the eggs. It's as if he was saying "I'll pass on the eggs, but just wait 'til this hen comes back!" But after a few days, the bobcat developed a taste for eggs. Bobcats left eggshells in the nest bowl, with a small, narrow opening in the middle of the egg. However, our sample of bobcat depredations was small; more variability might be expected if more samples had been obtained. Our goal was to develop "A Guide To The Eating Habits For Nest Predators Of West Texas." But we quickly realized that different factors such as egg size, the presence of other predators and perhaps even the cameras themselves may affect the distribution and condition of eggshells. Nevertheless, our findings are useful in assigning nest predators more objectively. From our findings, raccoons are the major egg predator in the western Edwards Plateau. Also, snakes may be getting an undeservingly bad "rap" about their importance as an egg predator. And roadrunners were exonerated of any wrongdoing, at least in our studies.
Results would vary with different communities of egg-eating predators. Interpreting nest crime scenes will never be a perfect science, but the availability of modern technology like these motion-sensing cameras has helped "crack" the case of egg "break ins" on Texas rangelands. Advances in camera technology, and concurrent price reductions, allow this experiment to be conducted on your back forty too. RPQRR, in conjunction with Texas Agrilife Extension Service and CKWRI will be producing a “webisode” on nest depredation later this summer. Stay tuned! Cadence call (Conservation cadences from the Bobwhite Brigade)
Featured Project of the Month Nesting Ecology of Bobwhites @ RPQRR
In the News West Nile Virus: a New Potential Threat to Northern Bobwhites Dean Ransom, Jr., PhD - Research Scientist, RPQRR When the topic of mortality agents, limiting factors, and population decline comes up for discussion among game bird ecologists, land managers, and quail hunters, the list of causes is often exhaustive and can include the who’s who in Hannibal Lecter’s toy box. For example, the list of predators that should, could, or would kill a bobwhite consists of a multitude of snakes (rat snakes to rattlesnakes), raptors (red-tails to shrikes), mammals (cotton rats to bobcats), hot weather, cold weather, and Granny’s speeding Buick. Further, being a close relative of the chicken, bobwhites are susceptible to a great many diseases and parasites (blackhead, fowl pox, eyeworms, coccidiosis). Avian ecologists have focused for decades on the role of predators and some good theory has been developed; generally, however, we have shied away from the population impacts of disease and parasites for two reasons: such aspects were not part of our university curriculum, and the nature of the specific diseases was often poorly known. This has produced a knowledge void that has now forced avian ecologists and veterinary pathologists in the U.S. to play 11th hour catch-up and get serious about disease impacts on bird population dynamics. Why? Well, there’s a new monster in Hannibal’s toy box, and it plays for all the marbles—it is known as West Nile Virus (WNv). There is little doubt that WNv made its North American debut in New York during 1999 and reached the west coast in 2004. As it swept across the country, it caused the death of a great many birds, mammals, and even humans. In fact, the appearance of WNv in birds tends to correlate well with infection rates in humans in some areas. The virus belongs to the encephalitis family of diseases that include western, eastern, and St. Louis encephalitis (African sleeping sickness). It appears to be primarily spread by mosquito vectors, but also by migratory birds, and there is some evidence that resident birds may provide a continuous reservoir for subsequent infection; infected birds can pass the virus to mosquitoes exacerbating the spread of the virus. The virus affects many different bird species to differing degrees, but its lethality, residence time, and efficacy of antibody resistance in many birds is not well known. But there are two exceptions that should keep bobwhite folks diligent. West Nile virus has devastating population effects on birds belonging to the corvid family, which includes all the crows, ravens, magpies, and jays. The susceptibility of corvids to WNv is so severe that this family of birds is now used as an early warning sentinel (e.g., the canary in the coal mine) by state and federal health departments. Research on a marked population of American crows in Oklahoma documented a loss of 72% of the studied crow population in a single year (2003) due to WNv; this study also reported that WNv mortality can reach 40% within 2 months of exposure to this virus. Similar research results have been found in other crow populations. In California, the disease appears to have reduced the population of yellow-billed magpies 90%, such that there is now concern for the future viability of magpies in that state. Post-exposure counts of crows, magpies, and northern shrikes in California have declined 83 %, 63 %, and 63%, respectively, compared to pre-exposure counts. It appears that the corvid family of birds has little to no resistance to the disease. Another species that is susceptible to the virus is the greater sage grouse, a large game bird of western sagebrush rangelands. In 2003, WNv caused a 25% decline in survival in four populations of radio-marked greater sage grouse across Alberta, Wyoming and Montana. Interestingly this was the same year as the massive crow mortality in the Oklahoma study. In the Powder River Basin of Wyoming and Montana, late summer survival of sage grouse was lower (20% survival) at a site with confirmed WNv mortalities than at two sites without WNv (76% survival). There were also dramatic declines in both male and female grouse lek attendance at the WNv site the following spring (2004), which suggests that outbreaks may threaten some local populations with extirpation. In 2004, WNv spread to sage grouse populations in Colorado and California, causing a 10% decline in female grouse survival. In this study, grouse that died of WNv were found intact, in good condition, with a full crop and no external signs of trauma. (Note: Bobwhites have been found dead at RPQRR and elsewhere in just such a condition.) To date, positive tests for antibodies are lacking, indicating that sage grouse show no resistance to this virus. This poses important conservation challenges for sage grouse given that they have been extirpated from greater than 50% of their historic range. How does this relate to northern bobwhites? It may, or may not relate at all. The situation with sage grouse is very disconcerting because of its hypothetical ramifications to other game birds such as northern bobwhites and other western quails, some of which have been declining for many years for a variety of reasons usually attributed to changing land use. West Nile virus impacted sage grouse survival during late summer, a time when survival would normally be quite high. Many of us have heard anecdotal stories of abundant bobwhites in early September which mysteriously disappear by opening day in November. Given what we know from corvids and sage grouse, if WNv was to sweep through bobwhite populations—and there is no evidence that it has—it might very well produce exactly that type of an effect….that is to say, here today, gone tomorrow. While it appears that WNv is a new bully on the block, caution is warranted. We know relatively nothing about WNv exposure in wild bobwhite populations, and at this time it would be irresponsible to speculate. That is worth repeating…we know relatively NOTHING about wild bobwhite susceptibility to WNv, and thus we must be cautious. As an example, look what the coffee-shop discussions from the quail hunting laity have done with Coccidiosis…it is, in many circles, the all explanatory reason du jour for the bobwhite decline, and there is absolutely no evidence for it, and no real biological reason for even hypothesizing about Coccidiosis. It is a disease of excessive crowding common in poultry houses and commercial game bird farms, and is likely meaningless in a population context among wild free-ranging quail. So, our working hypothesis should still remain fixed on habitat issues, but with a cautious eye towards the future. WNv, along with other emerging virulent diseases (Mycoplasma, bird flu, REV), should tell those of us in avian research and management that the conventional paradigms of our academic training may need to be updated. The only immediate course of action is rigorous, empirical research grounded in the scientific method that will generate reliable knowledge. Part and parcel to this is a long term monitoring protocol similar to what is currently described for sage grouse. It won’t be a quick fix, easy, or cheap, and coffee shop ‘just so’ stories are counter-productive to the process by distracting the clear, cogent formulation of research hypotheses (e.g., coccidiosis). Further, researchers cannot go it alone. Like all the previous population-habitat based research to date, this genre of research will require the assistance of serious and dedicated hunters and landowners, both financially and logistically, in order to shed light on this potential killer of quail. Pandora can’t help us, and Hannibal doesn’t care, so we must reason this one out on our own. Are U a fan of RPQRR or watching us Tweet? Catch us on Facebook . . .We're up to 350 fans and growing; check us out and forward onto your hunting buddies. Go to www.facebook.com/RPQRR or follow us on Twitter @ www.twitter.com/rpqrr. I have tasked my staff with providing latest news and observations as they happen each week. No Facebook or Twitter account is required to access these daily posts. Also check out other resources @ www.quailresearch.org Plant of the Month Annual sunflower (Helianthus annuus).
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Please mark your calendars for Friday, Oct 1, 2010 as the date for the 3rd Annual Field Day. We hope you will be able to join us then.
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Comments from a Reader I enjoyed reading your June 2010 e‑Quail newsletter. I don’t know if you would be entertained by a response or not. I did decide to take the time to respond because I believe it is often beneficial to press varying philosophies of management against one another. My imagination is stimulated when I read words like “quail decline,” or “the search for a smoking gun.” I made a graphic mental note regarding your comment about the possibility of having some “explainin’” to do. Part of this explanation may lie in our philosophy of quail management. Perhaps we may want to call into question: Is it a science? If we approach it as a science, then we are bound to apply the scientific method in order to identify the variable that either is “the limiting factor” or associated with it. If these ideas are fundamental in our philosophy, then this becomes the basis for notions like “quail decline” and “the search for a smoking gun.” If we are interested in quail management, then looking at the situation like this may, in fact, be a view point which is unrealistic and unproductive. In the alternative, let’s look at the situation in terms of what I believe to be more realistic and perhaps more productive way. Quail management in the year 2010 is more of an art than a science. There are reasons why this philosophy may be accurate and helpful. 1. The science of quail management is outdated. The fundamental rules of quail management go back to the 1930s. It won’t be long before that is 100 years ago! The science of quail management tends to assume that the circumstances for quail remain constant throughout time. Nothing is further from the truth. The general conditions for quail often go beyond our meager management capacities. 2. What controls a quail population is the accumulation of negative impacts in its surroundings. These impacts are many and overlap each other in varying ways. Some of these include: a. Current weather conditions. Bobwhite quail are a very temperate species; they do not like weather extremes. b. Changes in land use. What was once a collection of modest farms and pastures are now highly manicured bedroom communities of the Metroplex. c. Increase in predation. Since the 1930s birds of prey have been protected. The fur market is in the toilet, so no trapping goes on to speak of. We raise fewer sheep and goats, so the animal damage control efforts are down. A population such as raccoons not only benefits from these reasons, but also benefits from the large distribution of whole corn put out in association with deer hunting. d. Any of 10,000 other negative impacts you can come up with, to include, but not limited to: poor livestock management, fire ants, exotic grasses, competition with wild turkeys, aflatoxins, disease and parasites, etc., etc., etc. It is the accumulation of these factors that limit quail populations. The types and proportions of these factors are highly variable from site to site. So setting out to study the quail decline using the scientific method is somewhat futile. So you identify “the smoking gun” at one site—so what? Then you go to the next site and spend X amount of money and time to identify “the smoking gun” for that location. Great, you only have 9,998 situations to go before you have enough data to make an informed statement about quail management. Then that statement will be so complex it will not be useful in a practical sense. So let’s consider looking at quail management as an art, not a science. Keep in mind that the vast majority of game management that has been successfully performed on this planet has been applied as an art‑‑‑not a science. No better example exists than the bison of the West. The Plains Indians were highly successful bison managers. They used repetitive fire to retard woody vegetation, thus improving bison habitat. European man, during the occupation of the West, was highly successful in the collapse of this Indian culture. One of the primary tools that brought about this collapse was the eradication of one of the major food sources of the Indians—the bison. Both of these strategies were highly successful. Both were artistically applied. No science was involved. The overwhelming majority of successful wildlife management falls into this artistic scenario. So let us consider approaching quail management this way: It’s an art, not a science. We must cope with the reality of an ever‑widening area of declining quail production potential. Yet we don’t want to throw up our hands and say, “There is nothing I can do about it.” If you are interested in an area and its quail population potential, change what you are in control of in a positive manner. If it’s legal, within your budget, and seems to be working, continue. If it’s illegal, too costly, or doesn’t seem to be working, stop. When we practice thinking and acting this way, our efficiency as quail managers goes up. This way of thinking is far better than this “search for the smoking gun.” Taking a scientific approach to explain the quail decline is like setting out to explain the fishes of the Pacific Ocean using a dip net as the primary investigative tool. You invited comment. I took the time to do so. I hope my comments are received in the spirit in which they are given. That is, we share the passion associated with a mutual concern, and sometimes, it ishelpful to embrace an alternate philosophy. JV (Childress, TX) (Dr. Fred Guthery and I have bantered the art vs. science argument for many years; we finally came to a stalemate as defining quail management as “an art based on scientific principles.” – DR)
The Desert QuailMasters class met June 6-8 in Van Horn to continue their education. Tours of the Apache and Circle ranches demonstrated differing philosophies relative to grazing management. Most participants heard their first Gambel’s quail at Circle Ranch. The odyssey continues next month on the Armendaris and Ladder ranches near Truth or Consequences, NM. What a great place to discuss quail management , i.e., truth or consequences..
10. Take the number of bobwhite whistles you hear during a 5-minute listening period, and divide by 10, and you have a good estimate of how many cocks were calling.
Summer interns are busy on their various assignments. Dummy nests (n = 144) are at the halfway point; small mammal trapping is mostly completed. Floral inventories of forbs and grasses are in progress on burned and sprayed plots. Insect sampling will begin this month. Call counts continue each Tues and Thurs mornings; our average number of calling roosters per stop is 5.4, compared to 5.9 at this time in 2009. |
The saying "a bird nest on the ground" implies a windfall, a stroke of good luck, indeed a bonanza. For over a dozen species of Texas animals that prey upon quail nests, the phrase is an appropriate one. But for quail, or other birds that nest on the ground, the saying portends a challenge, if not an omen.
To determine what predators ransack quail nests, we used motion-sensing cameras to provide 24-hour surveillance of "artificial" (i.e., “dummy”) quail nests. The nests consisted of either 3 quail eggs or 3 chicken eggs. We used differently-sized eggs (i.e., quail versus chicken) to determine what effects egg size had on eggshell evidence associated with nest depredation. Our goal was to use photographs from the cameras to help us describe the individual predator‘s modus operandi at a nest. By comparing the size, appearance and distribution of eggshell fragments found at destroyed nests with the snapshot of the nest predator, we hoped to describe depredation patterns for particular nest predators.
Opossums typically carried off one egg at a time at least five yards from the nest bowl. They would then return for another egg, which might be carried a similar distance from the nest, but at a different location. Eggshell fragments were large and easily confused with those left by raccoons.
For example, coyotes are the most common egg-predator in Brooks County according to recent studies by CKWRI, whereas snakes are more important predators in forested areas.
The 2010 nesting season is off to a good start, and oh what a difference a year makes, eh? We discovered our first radiomarked hen with a brood on 17 June. Over these past two weeks, I’ve received numerous reports of broods across the Rolling Plains. In 2009, only thirty-two (27%) of the 120 radiomarked bobwhites alive on 1 May 2009 were observed to have nested; a total of 44 nests were monitored. Adult hens (n = 7) produced disproportionately more nests (13; 1.9 nests/hen) than juvenile hens (25 hens produced 31 nests; 1.2 nests/hen). Nesting occurred as late as mid-September. Almost 30% of nests were abandoned, which we attribute to observer interference. Discounting abandoned nests, the hatch rate was 72.7%. The most common substrate was bunchgrass, followed by bunchgrass-prickly pear. We use “dummy” (i.e., simulated) quail nests as an index to hatch rate of quail. Dummy nests consist of 3 chicken eggs situated in a suitable substrate as an actual quail nest. Nests are then checked for predation at 2 and 4 weeks. A total of 72 nests in rangeland (36 in grass; 36 in PP) and 72 in CRP (all grass) were established. The overall nest “success” (survival) in rangeland and CRP were similar, and “high” in both habitats, averaging 61%.
Perhaps the most widely distributed forb of significance to quail, annual sunflower is common along dirt roads and other disturbed sites. Leaves are as large as your hand and raspy. We appreciate sunflowers at RPQRR not only for their seeds, but also as brood cover. Discing during Dec-Jan tends to give us excellent responses. Our patch-burn sites in the Ellie Pasture (burned in Jan ’10) has produced an excellent stand of sunflowers. A smaller-leaved cousin (H. petiolaris) is also common on sandier soils. 
