Demography and Populations

Measures Of Breeding Activity

Age At First Breeding

Sexual maturity is generally reached at 80 d of age in males, 90 d in females (White et al. 1987). Proportion of hatching-year (HY) birds capable of breeding varies by sex and geographic region and from year to year. However, about 5–10% of HY females and 15–20% of HY males reach puberty within the same breeding season in which they were hatched. Although puberty is achievable at an early age, it must be reached while day length is still sufficient (approximately 750–775 min) to stimulate a reproductive response (White et al. 1987). The probability of attempted breeding in a given year is likely mediated by food resources and local weather, and successful fledging rate is reduced (Brown 1967, Armbruster 1983). The contribution from breeding immatures to annual recruitment is assumed to be negligible and most birds initiate breeding activity at one year of age.

Clutch

Determinate layer; clutch size = 2 eggs. Clutches containing 3 eggs generally ascribed to dump nesting (>1 female) while clutches with a single egg likely result from loss of the first egg.

Nesting Success

Total next success varies annually and spatially across the breeding range, as documented by several intensive studies. Annual success ranged from 37 – 58% in Iowa (McClure 1943), 52 – 87% in Illinois (Hanson and Kossack 1963), 30 – 41% in California (Miller et al. 2001). Sayre and Silvey (1993) reported an average of 48% nest success, compiled from nesting studies throughout the breeding range. In U.S., 83% of annual total of Mourning Doves fledged are produced in summer (May–Aug), 7% in spring (Feb–Apr), 10% in late summer–early fall (Sep–Oct) (Sayre and Silvy 1993). Nest failure is consistently greater during incubation stage than in brooding (McClure 1943, Miller et al. 2001, Hayslette 2001). Weather and predation appear to be primary influences on nest success (see Causes of Mortality, below).

Annual And Lifetime Reproduction

Average number fledged per nesting attempt (fledging success) was 1.1 in Iowa (McClure 1943), 1.2 in Illinois (Hanson and Kossack 1963), 0.7 in Missouri (Drobney et al. 1998), 0.7 in Texas (Hayslette et al. 2000), and 0.9 in California (Miller et al. 2001). Using data from Geissler et al. (1987), Otis (2003) estimated regional fledging success as 1.0 (northern Eastern Management Unit; EMU), 0.7 (southern EMU), 0.8 (northern Central Management Unit; CMU), 0.6 (southern CMU) and 0.8 (Western Management Unit; WMU). Multiple nesting attempts range from 2 – 7/yr, generally greater in southern latitudes.

Few direct estimates of total young fledged per individual breeding female during a breeding season. Martin and Sauer (1993) estimated a fall recruitment rate of 4.8 immatures per pair in the EMU, and Tomlinson and Dunks (1993) compiled production estimates in the CMU of 3.3 (northern latitude), 4.4 (mid-latitude), and 3.7 (southern latitude). A compilation of indirect estimates from field studies produced an average of 3.6 young fledged annually per breeding pair in U.S. (Sayre and Silvy 1993).

No direct estimates of lifetime reproduction. However, an average adult is expected to survive for only a single breeding season (see Life Span below), and therefore average lifetime and annual reproduction are roughly equivalent.

Survival And Life Span

Annual survival varies with geographical region and age; no consistent evidence to support gender difference in adult survival. Estimates are derived from a large scale banding study (prior) in late 1960’s – early 1970’s (Dunks et al. 1982, Tomlinson et al. 1988, Martin and Sauer 1993, Otis 2003) and an ongoing (current) study in 2003 – 2005 (Otis et al. 2008). Survival probabilities of adults in the prior study were 0.44 ( s.e. = 0.04; EMU), 0.54 (s.e. = 0.04; CMU), and 0.46 (s.e. = 0.03; WMU) and 0.34 (s.e. = 0.02; EMU), 0.43 (s.e. = 0.06; CMU), and 0.37 (s.e. = 0.09; WMU) in the current study. Survival probabilities of immatures in the prior study were 0.34 ( s.e. = 0.03; EMU), 0.44 (s.e. = 0.03; CMU), and 0.33 (s.e. = 0.04; WMU) and 0.26 (s.e. = 0.02; EMU), 0.32 (s.e. = 0.05; CMU), and 0.30 (s.e. = 0.08; WMU) in the current study. Telemetry studies produced estimates of 0.72 (s.e. = 0.07) for spring/summer adult survival probability in Missouri, and 0.94 (s.e. = 0.03; adult) and 0.87 (s.e. = 0.06; immature) for late summer survival in South Carolina (Berdeen 2004). Survival probabilities generally greater for northern latitude breeding populations, and generally for adults versus juveniles.

Expected life span about 1 yr for adults.

Disease And Body Parasites

Detailed review (Conti 1993) summarized here.

Viruses

Avian pox is manifested in both cutaneous and diphtheritic forms; Mourning Doves may have either or both forms simultaneously. Cutaneous form characterized by variable-sized nodules around eyes, beak, top of head, and on legs and feet (Locke et al. 1960a). Usually not fatal unless it occludes vision; once lesions disappear, at least partial immunity to further infection. Diphtheritic form is characterized by small, yellowish, diamond-shaped lesions in back of mouth that may develop into larger masses that can be lethal. These lesions are similar to those indicative of trichomoniasis, and laboratory culture is necessary to differentiate (Locke et al. 1960b). Mourning Dove is apparently little affected by other viruses.

Bacteria

Little known. Several different bacteria (Moraxella-like, Pasteurella-like, Mycoplasma spp., Micrococcus spp., Corynebacterium spp., and Bacillus spp.) isolated in 1 survey (Carpenter et al. 1972), but none considered pathogenic and no birds displayed clinical signs or exhibited gross disease.

Rickettsia

None observed in birds serologically tested (Carpenter et al. 1972), but Chlamydia infections do occur in other doves and pigeons.

Fungi

Several species of mycotic organisms reported from upper digestive tract (Kocan and Hasenclever 1972). Candida albicans most frequently encountered. These organisms apparently harmless in healthy birds.

Protozoa

Trichomonas gallinae, a flagellated protozoan, responsible for trichomoniasis, is probably most important cause of natural mortality in Mourning Dove populations. Found throughout geographical distribution with 4.4–10.6% of hunter-killed doves testing positive as asymptomatic carriers of for the parasite (Schulz et al. 2005a). Cheesy, yellowish growths in mouth and esophagus are typical lesions (Stabler and Herman 1951). Thought to be transmitted by asymptomatic carriers of the parasite through contaminated food and water, billing, and regurgitative feeding. Death usually results unless bird was previously exposed to an avirulent strain or survived a previous virulent infection. Widespread outbreaks have caused tens of thousands of deaths (Haugen and Keeler 1952, Kocan and Amend 1972). No recent widespread outbreaks have been documented, but small die-offs are regularly reported (Greiner and Baxter 1974, Ostrand et al. 1995), often occurring during hot and humid weather conditions. Determining occurrence, scale, and severity of trichomoniasis epizootics may be problematic, however, because relatively small, sick or moribund doves are difficult to sample from wild populations and are easily scavenged by predators, especially in less populated rural areas (Schulz et al. 2005a). Coccidia (Eimeria [7–42% of birds sampled], Sarcocystis [8–13%], Toxoplasma [1 report]) thought to occur throughout distribution and generally thought to be insignificant in free-flying birds. Plasmodium spp, Haemoproteus spp., and Leucocytozoon spp. are most common protozoan blood parasites (≥90% occurrence in birds sampled in some areas); no direct morbidity or mortality reported, but infection may indirectly affect survival by making birds more susceptible to other mortality factors.

Helminths

Most comprehensive studies (Barrows and Hayes 1977, Conti and Forrester 1981, Forrester et al. 1983) somewhat limited geographically but indicate helminths are not normally of serious concern to Mourning Dove populations. Nematodes (Ornithostrongylus spp., Ascaridia columbae, Dispharynx nasuta, Aproctella stoddardi, Tetrameres columbicola, Capillaria obsignata, Baylisascaris sp.) occur most often (< 1–67% of birds examined) and in greatest variety, followed by cestodes (tapeworms) (< 2%; Killigrewia delafondi, Hymenolepis sp., Raillietina spp.) and trematodes (flukes) (<1%; Echinostoma revolutum, Brachylaima sp., Tanaisia bragai).

Ectoparasites

Feather mites (Diplaegidia sp., Faculifer sp.) are most common (44–48% of samples). Nasal mites (Tinaminyssus zenaidurae), nest mites, and a feather-shaft mite (Syringophilus zenadourae) also reported. Four species of biting lice (Columbicola macrourae [35% of samples], Bonomiella columbae [24%], Physconelloides zenaidurae [19%], and Hohorstiella paladinella [1%]) reported. A variety of blood-sucking diptera feed on Mourning Doves, including mosquitoes (Culex tarsalis, C. pipiens, Orthopodomyia signifera, Aedes trivitattus), biting midges (Culicoides haematopotus, C. crepuscularis), black fly (Simulium aureum), and a variety of hippoboscid flies (e.g., Ornithoica spp., Stilbometopa sp., Microlynchia sp]); these blood-sucking species appear most important as potential vectors of pathogenic organisms such as avian pox.

Causes Of Mortality

Weather, predators (see Behavior: predation), diseases, parasites, (see above) are contributing factors. Anthropogenic causes (hunting, pesticides, lead ingestion, accidents): see Conservation and Management: effects of human activity.

Exposure

Nests and nestlings often lost during high winds and heavy rainstorms. Prolonged severe blizzards and ice storms can pose serious problems for individuals because of inability to dig through snow for food and water. Weather-related losses of nestlings and fledglings accounted for 33% of all known mortalities in Alabama, but weather ceased to be a factor for birds > 2 wk of age (Grand et al. 1984).

Competition With Other Species

Not documented. Captive bird experiments suggested high dietary overlap between Mourning Dove and the Eurasian Collared-dove (Streptopelia decaocto), but did not suggest significant foraging competition (Poling and Hayslette 2006).

Range

Initial Dispersal From Natal Site

Immatures disperse over a wider area and may not return to general natal area. For birds banded as immatures in Missouri, only 13 of 411 were recaptured at the site of banding in the ensuing 6 yr (Tomlinson et al. 1960). Authors concluded migratory homing occurred principally to first nesting sites rather than to natal areas.

Fidelity To/Dispersal From Breeding Site And Winter Home Range

In 20-yr banding study on Cape Cod, Massachusetts, > 50% of Mourning Doves that survived winter returned to the banding area each summer (Austin 1951). In 6-yr Missouri study, with allowances made for mortality and trapping inefficiency, nearly all adult males and 92% of adult females were estimated to return to the banding area after migration (Tomlinson et al. 1960). In Minnesota, 80% of nest sites of returning Mourning Doves were within 60 m of sites used in previous year (Harris 1961). Birds found nesting 2 yr after initial capture had moved an average of only 91 m from original nest sites. Under the assumption that Mourning Doves from these relatively northern areas migrate each year, it was concluded that birds returning from wintering areas are faithful to specific nesting locations (Tomlinson 1993).

Home Range

For fledglings and immatures, see Breeding: fledgling stage and immature stage. In Missouri, adult Mourning Doves had feeding and resting areas located considerable distances from nest sites (Sayre et al. 1980), with males ranging 1 - 8 km from nest site daily. Females sometimes seen as far as 5 km from nest. In Idaho, maximum distances traveled from feeding and loafing sites to nests averaged 4 km (Howe and Flake 1988).

Population Status

Numbers

Ranked second to Red-winged Blackbird in occurrence on 1989 North American Breeding Bird Survey routes; ranked eleventh of 251 bird species analyzed for relative abundance throughout its distribution (Droege and Sauer 1990). Among the most abundant bird species in U.S.; estimated population abundance range from 475 million (Dunks et al. 1982) to 350 million (DLO). In U.S., highest densities of breeders occur in southeastern coastal plain, upper Midwest, Central Plains from North Dakota south through Texas, and southern Arizona http://www.mbr-pwrc.usgs.gov/bbs/htm03/ra2003_red/ra03160.htm). Mourning Dove populations increase from spring through late summer; peak populations normally attained Sep–Oct, prior to migration.

Trends

Breeding population trends are indexed by both the Mourning Dove Call Count Survey and the Breeding Bird Survey (BBS), but results are often in conflict (Sauer et al. 1994). Generally, 1966 – 2006 survey results suggest stable or slightly decreasing trend in the Eastern Management Unit (EMU), and decreasing trend in the Central Management Unit (CMU) and Western Management Unit (WMU), with the greatest decline in the WMU (Dolton and Rau 2006). During the past 10 years, WMU trend is stable. Survey results for EMU and CMU are inconsistent. It is important to note that these surveys do not generally include urban areas, which may support an important population component in some regions with high human population density.

For BBS trend data, 1966-2003, see: http://www.mbr-pwrc.usgs.gov/bbs/htm03/trn2003/tr03160.htm .

Population Regulation

Mourning Dove populations experience very high annual mortality rates; depending on geographical region, 50 – 75% of the population dies each year. Significant causes of mortality include predation, hunting, weather events, disease, and chemical toxicosis, but the nature of the interactions among these sources is not understood. For example, there is only weak evidence that hunting mortality is additive to other causes (Otis 2003; see Conservation and Management: effect of human activity). There are no long-term data to ascertain whether reproduction is density dependent; significant competition for breeding sites seems unlikely, but fecundity could be controlled by available food resources. There is inadequate information regarding the amount of annual variation in recruitment and its relationship to factors such as climate. Neither intra- or interspecific competition has been well-documented. Important population regulation factors may be conditional on breeding range/migratory status. Migratory populations in northern latitudes tend to have higher survival rates than non-migratory populations in southern latitudes. A shorter breeding season in the north, with resultant lower fecundity than in the south, assuming equivalent nest success, is consistent with the hypothesis of tradeoffs in life history demographics, but factors that regulate population under either scenario are unknown.