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Richard D. Porter

Publications and source records attributed to Richard D. Porter.

9 recordsLinked to original sources
USGS1986

DDE, DDT + dieldrin: Residues in American kestrels and relations to reproduction

Captive American kestrels (Falco sparverius) given long-term dietary dosages of DDT and dieldrin in combination, at low and high rates, were compared with controls to determine the effects of the toxicants on reproductive success and eggshell thickness. Additional kestrels were dosed with DDE to determine its effect on shell thickness. Tissues of birds that died or were sacrificed, and eggs, were analyzed for DDE, DDD, DDT, and dieldrin. Eight paired birds, mostly males, given a high dosage of DDT + dieldrin died of dieldrin poisoning. Three periods of heavy mortality involving only dosed birds, which occurred in summer 1966, fall 1967, and spring 1968, followed temperature declines and other stress factors. Organochlorine concentrations in tissues of sacrificed birds and eggs in all units of the DDT + dieldrin study were significantly different among treatments. Residue concentrations in tissues of birds on high dosage of DDT + dieldrin were about 3 times higher than those on low dosage, a difference similar to the relative magnitude of the dose rates. Concentrations of some toxicants, especially DDE, were significantly higher in tissues of males than females, although these differences were difficult to interpret because males generally were sacrificed later than females. Concentrations in tissues and eggs of dosed yearlings, placed on clean food 7 to 9 weeks before pairing, were often significantly lower than in those yearlings that remained on dosage. Concentrations of each toxicant were usually highly correlated (r > 0.85) among tissues, especially for DDE and dieldrin. Organochlorine concentrations in brains and eggs could be predicted from concentrations in carcasses. DDE and dieldrin concentrations in eggs were about one-half those in carcasses, DDD about one-seventh, and DDT 1.5 to 2 times higher in eggs than carcasses. Eggshells of DDT + dieldrin-dosed kestrels were 6-23% thinner than eggshells of corresponding controls in different groups and years. Organochlorine concentrations in eggs and tissues of females were poorly correlated with shell thickness. Of the four toxicants in eggs, DDE was significantly and most closely correlated with fledging success. Interpretation of direct comparisons between our DDT + dieldrin studies and most current field situations are difficult because contaminant profiles in our birds are unlike those in most field samples.

Fish and Wildlife Technical Report↗
USGS1972

DDE at low dietary levels kills captive American kestrels

Two of 14 male American kestrels died after 14 and 16 months on a diet containing 2.8 p.p.m., wet weight, p, p'-DDE. The brains of the two birds contained DDE residues of 213 and 301 p.p.m. compared with 14.9 p.p.m. (range, 4.47-26.6 p.p.m.) (wet weights) for 11 of the adult males which were sacrificed after 12 to 16 months on dosage. Autopsies of the two birds compared with autopsies of the sacrificed birds, revealed other characteristics typical of DDE poisoning. Neither bird, when autopsied, displayed characteristics which would suggest that they died of causes other than DDE poisoning.

Bulletin of Environmental Contamination and Toxico↗
USGS1972

Reproductive patterns in captive American kestrels (sparrow hawks)

Female kestrels acquired in Florida in winter as full-grown birds began laying eggs a month later than did those acquired as nestlings from northeastern United States. Egg laying dates of the two groups did not overlap in 1966 through 1968. The later nesting Florida-wintering females may have nested in captivity at a latitude farther south of their normal breeding range than did those from the Northeast. There was an apparent trend of earlier laying in successive years between 1965 and 1968 in our captive birds.....Time intervals between pairing of previously unpaired kestrels and initiation of their first clutches ranged from 8 to 17 days; time intervals between removal of first-clutch eggs and initiation of second clutches for kestrels whose first clutches failed to hatch ranged frosm 11 to 16 days, with the exception of an apparent anomaly of 40 days. Some females laid second clutches prior to fledging of first-clutch young. The egg laying interval averaged 2.4 days, and appeared to be greater between the first two and last two eggs of the clutch than between intervening eggs. Egg sizes differed only slightly between age groups, and no statistical correlation was evident between weights of female kestrels and the size of their eggs.....Although both sexes incubated the eggs, the female assumed a much greater role than the male. Incubation of clutches of five eggs usually began with the laying of the fourth egg. The incubation period (last egg laid to last egg hatched) averaged 27 days. The average interval between hatching of the first and last eggs of clutches containing five eggs was two days.....The average nestling period for the first young hatched in 29 nests was 28.4 days. An exact 1:l secondary sex ratio was recorded in 1967 for complete clutches in which all young fledged.

Condor↗
USGS1970

DDE thins eggshells of captive American kestrels

EGGSHELL thinning in several species of raptorial and fish-eating birds, whose populations and/or reproductive success have declined dramatically in recent years, has been correlated with residues of DDE [1,1-dichloro-2,2- bis ( p -chlorophenyl) ethylene] in their eggs 1–3 . DDE, a common metabolite of DDT [1,1,1-trichloro-2,2- bis ( p -chlorophenyl) ethane] and a nearly universal contaminant in the food of these birds, has been considered to be the major chemical responsible for eggshell thinning.

Nature↗
USGS1970

Propagation of captive American kestrels

A colony of kestrels ( Palco sparverius ) was established at the Patuxent Wildlife Research Center in 1964 in connection with work on pesticides. The kestrels were acquired from the wild, both as nestlings and as full-grown birds, and were housed in several rows of outdoor pens. Each 50 x 20 ft pen was covered with wire netting and had its long sides in common with adjacent pens. During the first two reproductive seasons, untreated parent birds (dosed birds are not included in this paper) ate eggs and young. Cannibalism virtually ceased after the diet was changed from ground beef or horsemeat supplemented with liver, vitamins, and minerals to one containing a finely ground mixture of laboratory rodents, chicken heads, skinned chicken necks, and supplements; hatching success thereafter generally equaled that of a wild population. In 1967, 16 pairs of untreated hawks (3-year-old females) laid clutches averaging 4.9 eggs, hatched 88 percent of their eggs, and fledged 88 percent of their young. In 1968, 10 pairs of this group (4-year-old females) laid clutches averaging 4.9 eggs, hatched 51 percent of their eggs, and fledged 85 percent of their young. Nine yearling pairs (hatched in captivity) laid clutches in 1968 averaging 5.1 eggs, hatched 87 percent of their eggs, and fledged all of their young.

Maryland↗
USGS1969

Dieldrin and DDT: Effects on sparrow hawk eggshells and reproduction

Patterns of reproductive failure in declining populations of several European and North American raptorial species were duplicated experimentally with captive American sparrow hawks Falco sparverius that were given a diet containing two commonly used organochlorine insecticides. Major effects on reproduction were increased egg disappearance, increased egg destruction by parent birds, and reduced eggshell thickness.

Science↗