Fresh semen characteristics in captive accipitrid and falconid birds of prey

Abstract

Artificial insemination (AI) is the most frequently used assisted reproductive technique for captive propagation of rare avian species. As semen quality is critical for reproductive success, baseline data are needed for evaluating and selecting the best male bird donors. To this end, we used computer-assisted semen analysis to assess male eastern imperial eagles (n = 7), northern goshawks (n = 24) and peregrine falcons (n = 20). While imperial eagles and northern goshawks donate ejaculate voluntarily, peregrine falcons required cloacal massage. Eight peregrine falcon females were inseminated with semen from eight males, with fresh ejaculates (15 to 50 µl) applied to the pars uterina of the oviduct immediately after collection and examination. All females were inseminated within 2 h of laying an egg. A fertilization rate of 70% was achieved using this method. Minimum semen characteristics associated with egg fertilization included a semen concentration of 115.12 × 106/ml, 33.52% total motility, 1.92% spermatozoa with progressive motility and 0.17% with rapid motility. Comparative data on spermatozoa concentration and kinematics suggest that eastern imperial eagles concentrate on high quality semen investment at the start of the breeding season, northern goshawks compensate for a decrease in motility-associated parameters with increased semen concentration and peregrine falcons maintain semen production standards throughout the breeding season. Our data show that, in birds of prey, levels of egg fertilization following AI with fresh semen can be almost as successful as after natural mating.

Raptors bred in captivity: semen characteristics and assisted reproduction outcome in goshawk (Accipiter gentilis)

“…On the contrary, the concentration of spermatozoa in ejaculates observed in our study (41.0 ± 25.4 × 10 6 /mL) was lower than that reported by Piacek et al (2020) for the same species (110.2 ± 63.2 × 10 6 /mL). This difference is probably linked to the duration of the collection period, as the latter authors evaluated semen collected in April only.…”

“…The influence of the semen collection method on the quality of the fresh semen has been clearly demonstrated in a number of avian species ( Castillo, Marzoni & Romboli, 2009 ; Łukaszewicz, Kowalczyk & Rzońca, 2011 ; Castillo et al, 2021 ; Tang et al, 2021 ). The massage method, the most common approach for semen collection ( Łukaszewicz, Kowalczyk & Rzońca, 2015 ; Dogliero et al, 2016 ; Piacek et al, 2020 ), may also stimulate urination and/or blood emission in the case that the handler’s dexterity is insufficient, with the consequent contamination of the ejaculate ( Madeddu et al, 2009 ). It is known that a watery ejaculate or its contamination with faeces markedly reduces sperm longevity and their fertilizing capacity ( Lake, 1971 ; Fujihara & Nishiyama, 1976 ).…”

“…The latter offers two key advantages: it can help increase genetic diversity by using under-represented males ( Waldoch et al, 2007 ; Blanco et al, 2009 ) and boost the remaining populations by returning captively bred birds back into the wild ( Neumann, Kaleta & Lierz, 2013 ; Dogliero et al, 2016 ). Considering this context, reproductive biotechnologies, such as artificial insemination (AI) and semen cryopreservation, have acquired an increasingly important role in wild bird species preservation, and their application is receiving research attention ( Samour, 2004 ; Madeddu et al, 2009 ; Schneider et al, 2019 ; Cardoso et al, 2020 ; Piacek et al, 2020 ).…”

“…The semen characteristics of a number of bird of prey species bred in captivity were recently described with the scope of improving breeding techniques ( Dogliero et al, 2016 ; Frediani et al, 2019 ; Fischer et al, 2020 ; Piacek et al, 2020 ). However, much more research is needed to obtain semen quality data that will be useful for testing appropriate techniques on rare avian species and for developing reliable, applicable protocols for cryopreservation.…”

“…As regards the goshawk ( Accipiter gentilis —Linnaeus 1758), only limited information is available on male reproductive aspects. Some data is available on the quality of manually collected semen, but for only a short interval of the reproductive period ( Piacek et al, 2020 ), whereas no information has been published on the use of other collection methods or on whether the performances of males chosen as sperm donors remain high in subsequent reproductive seasons. Furthermore, almost nothing is known about the morphology and ultrastructure of the goshawk spermatozoon.…”