SAMPLING BLOOD FROM BIRDS : A TECHNIQUE ASSESSMENT OF ITS EFFECT ’ AND AN
The Condor (1991)
Blood sampling is not obviously detrimental to birds. AOU 1988 guidelines no more than 10-20% of total blood volume should be collected. Mortality with 30-50% collection.
SAMPLING BLOOD FROM BIRDS : A TEC...
The Condor 93:746-752 0 The Cooper Ornithological Society 1991 SAMPLING BLOOD FROM BIRDS: A TECHNIQUE AND AN ASSESSMENT OF ITS EFFECT��� DREW J. HOYSAK AND PATRICK J. WEATHERHEAD~ Department of Biology, Carleton University, Ottawa, Ontario KIS 5B6, Canada Abstract. We describe a technique and apparatus for extracting blood samples from birds in the field. We tested the effect of our technique on the health and behavior of captive Brown-headed Cowbirds (Molothrus ater) and free-living Red-winged Blackbirds (Agelaius phoeniceus). We found that captive Brown-headed Cowbirds that had been bled did not lose any more weight than birds that had not been bled. Territory loss by male Red-winged Blackbirds was not affected by taking blood samples, nor was annual return rate. Female Red-winged Blackbirds that were bled did not differ signiEcantly in their rate of nest aban- donment, nest success, fledging rate or annual return relative to females that were not bled. We conclude that blood sampling is not obviously harmful to wild birds as long as proper precautions are taken. Given the ease of the field technique and the vast potential for information to be gained, field ornithologists should not preclude adding laboratory blood analyses to their research program because of concerns about the technique negatively affecting the birds��� health or behavior. Key words: Blood sampling Red-winged Blackbird Brown-headed Cowbird Agelaius phoeniceus Molothrus ater. INTRODUCTION Many insights into avian biology have been gained with techniques involving laboratory analysis of blood samples taken from wild birds. Avian blood can yield information for a wide variety of disciplines, including endocrinology (Oring et al. 1988), energetics (Utter and Le- Febvre 1970) genealogy (Sherman 198 1, Burke 1989), hematology (Puerta et al. 1990), pathol- ogy (Seegar 1979), population genetics (Evans 1980, Barrowclough et al. 1985, Burson 1990), and taxonomy (Sibley and Ahlquist 1983). How- ever, field ornithologists may be reticent about extracting blood from their study animals be- cause of a lack of clearly defined and readily available accounts of field techniques and a fear that birds will be adversely affected by the pro- cess. A wide variety of techniques and apparatus for blood sampling have been described (American Ornithologists��� Union 1988). They involve ei- ther extracting blood directly from a vein with a hypodermic needle and syringe or puncturing a vein with a needle and then drawing blood off of the skin surface with capillary tubes or sy- ringes. However, methods have rarely been il- I Received 4 February 199 1. Final acceptance 18 April 1991. 2 Corresponding author. lustrated (but see Kerlin 1964 and Arctander 1988) and descriptions have not been sufficiently explicit to allow new researchers to adopt the techniques without extensive trial-and-error learning. Therefore, our first objective in this pa- per is to describe a method we have developed for use in the field. In addition to overcoming methodological problems, researchers who wish to collect blood samples from wild birds must also satisfy them- selves that the collection technique does not ad- versely affect the study animals. Obviously, in- terpretation of behavioral or ecological data must take into account any effects that research activ- ity has on the study animal. In general, birds are known to be fairly resilient to blood loss since they do not exhibit acidosis and thus do not go into shock when blood is lost (Sturkie 1986). Therefore, they can survive relatively greater blood loss than mammals (Kovach et al. 1969). A lack of effect of blood sampling on survival in the wild has been documented for a number of species (Franks 1967, Raveling 1970, Wingfield and Famer 1976, Bigler et al. 1977, Evans 1980, Colwell et al. 1988, Dufty 1988). Other studies have suggested that blood sampling does not af- fect mass changes of birds in captivity (Evans 1980, Stangel 1986). Although survival and mass changes are not obviously affected by blood sam- pling, very few studies have examined shorter term effects, particularly on behavior. Anecdotal W61
AVIAN BLOOD SAMPLING 147 evidence suggests that bird behavior is not strongly affected by blood sampling (LeFebvre 1964, Utter and LeFebvre 1970, Utter et al. 197 1, Winglield and Farner 1976, Frederick 1986). However, the only experimental study of effects on behavior yielded mixed results (Colwell et al. 1988). In their study of blood sampling effects on nest desertion for three shorebird species, Col- well et al. (1988) found that the rate of nest de- sertion by the two uniparental species was not affected by bleeding the attending parent. How- ever, incubating biparental Semipalmated Sand- pipers (Calidris pusilla) were more likely to des- ert nests if blood was taken from both parents than if neither parent was bled. Collectively, the studies done to date suggest that blood sampling does not have a strong det- rimental effect on birds, but the evidence is far from comprehensive. Therefore, our second aim in this paper is to present the results of two stud- ies we undertook to determine whether our blood sampling technique is harmful to birds. In one study we examine the short term effects of blood sampling on mass changes in Brown-headed Cowbirds (Molothrus ater) maintained in an avi- ary. In the other study we look at both short and long term effects on reproductive performance and survival of free-living Red-winged Black- birds (Agelaius phoeniceus) over a six-year breeding study. METHODS BLOOD SAMPLING TECHNIQUE Below we describe both the method and some of the considerations that led us to it, with the intention that this information will help others wanting to sample blood in the field. However, we recognize that for different researchers and different bird species, modifications of the tech- nique may be required to make it more effective. In establishing a blood sampling technique, we sought a method that would allow one person to take relatively large samples (0.5 ml) in the field with minimum disturbance to the birds being sampled. Preliminary testing was done on a group of captive male Red-winged Blackbirds. We first tried to collect blood using the wing vein tech- nique (Arctander 1988). This method did not work well because most needles were too large to be easily inserted into the vein. Puncturing the vein and drawing blood off the surface also met with little success because the blood coag- ulated too quickly. These problems were over- come by extracting blood directly from the jug- ular vein (Kerlin 1964). The optimal syringe-needle combination for this technique depends on the size of the bird (or vein size), the amount of blood required and the researcher��� s personal preference. Larger volume syringes can be easier to work with since less motion of the plunger is required for a given volume of blood. Larger needle diameter also makes blood collection faster and easier, but a small needle is less likely to cause injury to the bird. We used a 3 ml Becton-Dickinson syringe with a 19 mm 27.5 g or 30 g needle. Our technique for holding a bird and extract- ing blood (Fig. 1) allows one person to perform the blood extraction while simultaneously lim- iting movement of the bird. The bird is held firmly in the left hand with the head between the index and middle fingers and the legs between the ring and small fingers. The jugular vein is exposed by pulling down on the right wing with the ring and small fingers and blowing on the feathers just above the bird��� s right shoulder. It may be necessary to turn the head to the left or right in order to make the vein stand out as much as possible. Once a firm hold on the bird has been estab- lished, the area around the vein is sterilized by swabbing with alcohol. This also moistens the surrounding feathers, which then can be groomed away from the vein, allowing even clearer access. The syringe is held in the sampler��� s right hand with the needle approaching the vein at an acute angle (about 15 degrees) to the skin and the sur- face of the needle tip facing upwards. The needle can be steadied by resting the hand on the bird��� s body. The needle should be inserted into the skin by moving the needle forward slowly and ad- justing its angle if necessary. The vein is pene- trated in a similar fashion by slowly moving the needle forward and adjusting its angle. Both the skin and vein usually offer some resistance to puncture and will be pushed forward by the nee- dle to some extent, but will spring back to the original position once the needle has penetrated. Thus, if the needle is pushed forward too quickly, it may be difficult to control the depth of pene- tration. This is especially important when pierc- ing the vein, because too much force may result in the needle piercing right through the vein. Once in the vein, the needle should be inserted to a depth of 0.5 to 1.0 cm. Blood is then ex-
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