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TEST OF GRIT TYPES IN ALLEVIATING LEAD POISONING IN MALLARDS

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UNITED STATES DEPARTMENT OF THE INTERIOR

FISH AND WILDLIFE SERVICE

BUREAU OF SPORT FISHERIES AND WILDLIFE

Special Scientific Report - Wildlife No. 107

UNITED STATES DEPARTMENT OF THE INTERIOR, STEWART L. UDALL, SECRETARY Stanley A. Cain, Assistant Secretary for Fish and Wildlife and Parks

Fish and Wildlife Service, Clarence F. Pautzke, Commissioner Bureau of Sport Fisheries and Wildlife, John S. Gottschalk, Director

TEST OF GRIT TYPES IN ALLEVIATING LEAD POISONING IN MALLARDS

By Alfred J, Godin Patuxent Wildlife Research Center, Laurel, Maryland

Special Scientific Report — Wildlife No. 107 Washington, D.C. • June 1967

For sale by the Superintendent of Documents, U.S. Oovemment Printing Office Washington, D.C. 20402 - Price 16 cents

CONTENTS

Page

Abstract ii

Materials and methods 1

Results 2

Mortality 2

Body weight losses 3

Shot retention 3

Food consumption 4

Gizzard examination 4

Conclusions 4

References 5

Tables ; • . 6

ABSTRACT

Mallard ducks (Anas platyrhynchos) were given either 0, 2, or 4 No, 6 lead shot in combination with 4 grit treatments; no grit, coarse sand, mica granite, and crushed oystershell. Each combination was replicated three times. Ducks were maintained on a diet of whole corn. An analysis of variance indicated no significant differences in mortality in relation to grit type, but a significant difference (at 0.05 level) in mortality between the lead shot doses. Oystershell grit apparently reduced mor- tality of ducks dosed with 4 shot but not to a degree statistically significant. In all treatments, mortality was closely associated with shot retention. Ducks retaining shot for 2 weeks usually died.

11

TEST OF GRIT TYPES IN ALLEVIATING LEAD POISONING IN MALLARDS

For many years wildlife investigators and sportsmen alike have been concerned over the annual waterfowl mortality caused by lead poisoning. Wetmore (1919) and others focused on the fact that lead poisoning frequently occurred in wintering areas deficient in grit and suggested grit be added to such areas. As part of the current research being conducted on lead poisoning by the Section of Wetland Ecology of the Patuxent Wildlife Research Center, a study was initiated to determine possible effectiveness of various grit types in alleviating lead poisoning.

Special thanks are extended to Hsin-yuan Tu, Geologist, Soil Survey Laboratory, Soil Conservation Service, U.S. Department of Agriculture, Beltsville, Md. , for determining the mineral and chemical composition of grit types. Thanks are also due biolo- gists Harold D. Irby, Louis N. Locke, Robert G. Heath, and John L. Sincock, Patuxent Wildlife Research Center, for their valuable assistance.

MATERIALS AND METHODS

A 60-day test was made using 288 first-year, drake mallards. The ducks were obtained in late July from a breeder in Birdsboro, Pa. Two weeks before initiation of the study, the ducks were wing-clipped (primaries cut off one wing) and placed in 36 pens for conditioning. Pens were 9x5x2 feet high and provided with a 260- gallon stock-watering tank (Cornwell and Hartung, 1963). Each pen and tank was partitioned into two units to hold eight ducks. Birds were deprived of grit during this conditioning period. Before putting J:he birds on test, grit removal was attempted on 12 live mallards with a water aspirator (Nord, 1941). This was found impractical and was discontinued.

A 3 X 4 factorial comparison was made of the effects of 3 quantities of No. 6 lead shot per bird (0, 2, and 4) in combination with, (1) no additional grit and the addition of (2) coarse sand, (3) mica granite, and (4) crushed oystershell. The 12 treatments were replicated 3 times and randomly assigned to the 36 pens. Since treatments could not be initiated in all pens at one time, the replicates were "blocked" into 3 time periods, each period being assigned 1 pen of each of the 12 treatments. The replicates were initiated between August 26 and September 13, 1965.

Lead shot were placed in the gizzard using a funnel and small plastic tube. Initially each duck was weighed and leg-banded. Body weights were also recorded at 14- day intervals, at the time of death, and at the end of the test. All ducks were fluoroscoped on the 14th and 28th day after dosing to determine shot retention. Ducks not given lead were fluoroscoped to provide comparable handling.

Cages were flushed with water daily and each tank was drained, cleaned, and refilled every 3 days. Whole corn and the assigned grit were offered ad libitum.

The average daily corn consumption per duck was calculated at intervals for each treatment group by multiplying the number of surviving ducks by the number of days required to nearly empty a feeder. The bird-days for a group were calculated when- ever a duck died and the amount of corn consumed was divided by the bird-days to estimate average consumption per bird day.

At the end of the test, surviving ducks were killed and all ducks necropsied. The condition of the gizzard and the number of lead shot retained were recorded.

RESULTS

Mortality

Percent mortality over the 60-day period for all treatment replicates is shown in Table 1. The greatest mortality of ducks given lead shot, regardless of grit type, occurred between 16-20 days after dosing. Within 25 days after dosing, 27 percent of the ducks given 2 shot, and 51 percent of the ducks given 4 shot, succumbed. Only 8 ducks which had been given lead lived beyond the 25th day after dosing.

An analysis of variance of percent mortality for the first 25 days (Table 2) showed no significant difference among grit types. A significant difference in mortality between the 2-shot and 4-shot doses was demonstrated at the 0.05 level of significance. The mean percents of mortality over the first 25 days for 2 and 4 shot treatments, regardless of grit type, were 28 and 53, respectively. Over the 60-day period mean percents of mortality for the 2 and 4 shot treatments were very similar at 35 and 54, respectively.

Body Weight Losses

The percent loss of initial body weight at 14-day intervals over the 60-day test is presented in Table 3. The peak weight losses (up to 24 percent) among all grit treatments and shot doses were recorded during the first 28 days. Ducks which died during the test, however, frequently lost more than 50 percent of their initial body weight.

Weight losses among lead-dosed survivors and those birds not given lead were similar. The consistent weight loss by all birds could have resulted from the inadequacy of the corn diet. Several factors could explain why weight losses among lead-dosed survivors were less than expected: Survivors may have rid them- selves of shot early enough to avoid poisoning; they may have been hardier birds initially; or, as mortality progressed, they may have experienced less stress from crowding than did the undosed birds. There was no apparent relationship between mortality and initial body weight.

Shot Retention

The percent of shot retention, as determined by fluoroscopy, for mallards surviving 14 and 28 days after dosing is presented in Table 4. Fourteen days after dosing, 29 percent of those ducks given 2 shot and 54 percent of those ducks given 4 shot had retained at least 1 shot in their gizzards. Twenty-eight days after dosing only one surviving duck (on 2 shot dose) had retained shot.

All ducks on coarse sand which had retained shot at 14 days died before fluoroscopy on the 28th day. However, all ducks which passed their shot before the 14th day survived the 60-day test (Table 5).

Of the ducks given 4 shot, a higher percent of those on oystershell grit retained shot to the 14th day than on other grit types. Paradoxically, ducks on oystershell grit and given 4 shot suffered the lowest percent mortality of the 4 grit treatments.

The number and percent of ducks which retained shot at death for each grit treatment are shown in Table 6. Slightly more than half of the ducks given 2 lead shot and offered coarse sand, mica granite, and oystershell grit retained shot at death.

Bellrose (1959) cited work by Jordan that showed penned, wild mallards which were force fed 1 or more No. 6 shot passed the shot as early as the first week or as late as several weeks after dosing. This was also true in this study.

Food Consumption

The average daily corn consumption per duck for the control ducks (no grit, no shot) during the 60-day test was 0,12 pound. This corresponds closely with Jordan's (1953) study in which wild penned mallards consumed 0.13 pound of corn daily in early fall. Corn consumption by birds for each treatment is shown in Table 7. Average consumption per bird decreased with increased shot dose on all grits except crushed oystershell.

Gizzard Examination

Among birds which died during the test in the same treatment, pathological conditions of the keratinous pads and interpad mucosa of the gizzards varied from a normal yellow color to dark, greenish- brown staining with ulcerations.

The gizzards of the 60-day survivors on crushed oystershell had a characteristic white coating on the inner lining, and the gizzards of the survivors on other grits appeared a normal yellow color without ulcerations.

Ducks not offered additional grit retained considerable grit which had been ingested before they were put on test.

CONCLUSIONS

1. Mortality of lead-dosed mallards varied among treatment replicates. The greatest mortality of ducks on the different grit types and given 2 or 4 shot occurred 16-20 days after dosing. Bellrose (1959) observed that mallards with lead shot still in the gizzard died on the average of 21 days after ingesting it, and that 20 days was the average "turnover" period of leaded mallards in the wild.

2. An analysis of variance indicated no significant differences in mortality in relation to grit types, but a significant difference at the 95 percent level of confidence was demonstrated in mortality between shot dosage levels. The total mortality of ducks given 4 shot was lowest for the group an oystershell grit but the difference was not statistically significant. However, the comparatively lower mortality of lead-dosed ducks given oystershell grit suggests that further studies of a calcium grit might be fruitful.

3. The greatest body weight losses occurred in the first

28 days after dosing among all treatments. Ducks that died which had been given either 2 or 4 lead shot lost an average of 54 percent of their initial body weight. There appeared to be no relation between mortality and initial body weight.

4. Shot retention 2 weeks after dosing as determined by fluoroscopy was greater in the ducks given 4 shot than those given 2 shot. Twenty-eight days after dosing only one surviving duck had retained at least one shot. Although a greater percent of the ducks given crushed oystershell grit and 4 lead shot had at least 1 shot at 14 days. This group of ducks suffered the least mortality among the other grit treatments given 4 lead shot.

5. Gizzards of lead-dosed mallards which died during the test were stained a dark, greenish-brown and had ulcerations.

LITERATURE CITED

Bellrose, Frank C. 1959. Lead poisoning as a mortality factor in waterfowl populations. Illinois Natural History Survey Bulletin 27(3) :235-288. Urbana Illinois.

Cornwell, George and Rolf Hartung. 1963. A holding pen for

diving ducks. Journal of Wildlife Management 27(2) : 290-292.

Jordan, James S. 1953. Consumption of cereal grains by migratory waterfowl. Journal of Wildlife Management 17(2) : 120-123.

Nord, Warren H. 1941. A technique of removing lead from the gizzards of living waterfowl. Journal of Wildlife Management 5(2) : 175-179.

Wetmore, Alexander. 1919. Lead poisoning in waterfowl. USDA Bull. 793:1-12

Table 1. Mortality (in percent) durin<? a 60-day test among replicated pens of 8 mallards each treated with grit and lead shot.

				Percent Mortal	ity by Repl:	Lcates
					Lea	d Shot Doi	sage
		No	Shot		2	Shot			4	Shot
Treatment	A	B	C	Ave.	A	B	C	I've.	A 25	B 50	C Ave.
No Grit	0	0	0	0	25	38	38	33	100 58
Coarse Sand	0	13	0	4	50	13	25	29	13	100	75 63
Mica Granite	0	0	0	0	25	38	50	38	65	50	63 58
Crushed	0	0	0	0	38	13	75	42	25	38	50 38
Oystershell
Mean				1				35			54

Table 2. Percent mortality for first 25 days among 8 duck

replicates given lead shot and various grity types.

Oystershell

		Percent Mortality by Replicates
		Lead Shot Dosage
		2 Shot 4 Shot
Treatment	A	B C Ave. ABC	Ave,

No Grit	25	25	25	25
Coarse Sand	50	13	25	29
Mica Granite	25	13	50	29
Crushed	25	0	63	29

Mean

28

25 50 88 54 13 100 75 63 63 50 63 58 25 38 50 38 53"

Table 3. Percent loss of initial body weight of survivors at 14 day intervals over 60-day test period.

Lead Shot Dosage

No Shot 2 Shot 4 Shot

Day Day Day

Treatment No. 14 28 42 56 60 No. 14 28 42 56 60 Na. 14 28 42 56 60 Birds % Wt. Loss Birds % Wt. Loss Birds % Wt. Loss

No Grit 24 8 11 12 14 16 16 7 9 9 11 12 10 9 8 6 9 12

Coarse 23 6 9 11 11 12 17 13 12 11 10 10 9 13 13 9 7 6

Sand Mica 24 n 13 n n H 15 11 12 13 12 11 10 24 22 18 17 18

Granite Crushed 24 11 12 11 10 10 14 4 6 5 4 4 15 10 10 10 8 8 Oyster she 11

Table 4. Retention of at least 1 shot in the gizzard as revealed by 14 and 28 day post-dosage fluoroscopy.

			Lead Shot	Dosage
		2	Shot			4	Shot
	14	days	28	days	14	days	28	days
Treatment No. Dosed	No. Alive	7o with 1 Shot	No. Aliv£	7o with : Shot	No. Alive	7o with i Shot	No. Alive	7o with ; Shot
No Grit 24 Coarse Sand 24 Mica 24 Granite Crushed 24 Oystershell	23 23 24 24	48 13 25 29	18 20 19 19	6 0 0 0	21 22 23 24	52 50 48 63	11 11 12 15	0 0 0 0
Total Average	94	29	76	1	90	53	49	0

Table 5. Shot retention (at least 1 shot) by 60-day survivors given 2 or 4 lead shot as determined by 14 and 28 day post-dosage fluoroscopy.

					Lead	Shot	Dosage
		2	Shot				4	Shot
Treatment	No. Dosed	60-day survivors	7o with 14 day	shot 28 day	60-day survivors	7o with 1 14 day	shot 28 day
No Grit	24	16		25			6	10	10	0
Coarse Sand	24	17		0			0	9	0	0
Mica Granite	24	15		7			0	10	10	0
Crushed Oystershell	24	14		7			0	15	40	0

Table 6. Number of mallards which died during the 60-day test and retained at least 1 lead shot.

Lead Shot Dosage

Treatment No. 2 Shot 4 Shot

Dosed No. Died 7o with shot No. Died 7. with shot

No Grit 24 8 100 14 93

Coarse Sand 24 7 57 15 87

Mica Granite 24 9 56 14 86

Crushed 24 10 60 9 100

Oystershell ,

Table 7. Food consumption per bird per day (lb.) over 60-day test for mallards given various types of grit and lead shot.

Treatment

Average food intake per bird per day (lb.) Lead Shot Dosage

No Shot

2 Shot

4 Shot

No Grit .12

Coarse Sand . 11

Mica Granite . 10

Crushed Oystershell .09

10 09 10 09

08 08 09 09

Mean

.11

10

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Note — The author's present address is

Alfred J. Godin , State Supervisor Wildlife Services, USBSFW 256 State Office Building Hartford, Connecticut 06115

* U S, GOVERNMENT PRINTING OFFICE . 1967 0—274-763

The Department of the Interior, created in 1849, is a Department of Conservation, concerned with management, conservation, and develop- ment of the Nation's water, wildlife, fish, mineral, forest, and park and recreational resources. It has major responsibilities also for Indian and Territorial affairs.

As America's principal conservation agency, the Department works to assure that nonrenewable resources are developed and used wisely, that park and recreational resources are conserved for the future, and that renewable resources make their full contribution to the progress, pros- perity, and security of the United States, now and in the future.

UNITED STATES

DEPARTMENT OF THE INTERIOR

FISH AND WILDLIFE SERVICE

BUREAU OF SPORT FISHERIES AND WILDLIFE

WASHINGTON. D. C. 20240

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